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I have a wireless reversing camera (AutoVox TD2) fitted to my car which switches on the screen when I engage reverse gear (power from reverse light connection). It functions perfectly with one exception, when I disengage reverse gear the screen switches off, ie the camera has no more power to it. Is there a way to maintain the power (12v) running to the camera for 10-20 seconds, as I manoeuvre the car, as in parking?
Please try the following circuit, it will fix the issue instantly:
https://www.homemade-circuits.com/wp-content/uploads/2024/04/reverse-car-camera-delay-OFF-circuit.jpg
The delay OFF time can be tweaked by adjusting the values of the 2.2M resistor or the 1000uF capacitor, or both.
Thank you for your prompt reply!
You are welcome. Let me know if you need any further help…
Very kind of you, thanks again!
Can I connect this circuit by joining the wires in parallel, is there a need for any diodes to prevent current reversing if I do ?
For the +/- supply connections, you can add a 1N5402 diode in series with the positive (+) supply line to safeguard against an accidental reversal of the supply polarity.
For the output from the TIP127 there’s no need to add a diode, since the camera device would be having an internal diode with its own circuit.
Please note that the pnp transistor is mistakenly shown as TIP122, it should be actually a TIP127.
Hello Swagatam,
I am interested in your project Mobile Phone Controlled Robot Car Using DTMF Module. I need to buy it. Can you give me details to purchase it.
Thank You Chaitanya,
I understand your requirement. However, I do not build or sell readymade kits nowadays, so selling the unit may not be possible for me.
Hi ,
By reading all the comments, i am overwelmed to see a mosquito window powered by electricity. I am not a technical guy to build it but looking for such products to purchase.
My colony has high presence of mosquitos and every now and then someone is getting sick.
Hence a sincere request to buid the mosquito window. I am willing to bear all expenses related to the creation and installation of such window. However, if similar products are already available in the market, I would appreciate it if you could share any relevant links or information to purchase them.
Thank you for considering my request. I look forward to hearing from you soon.
Hi, I am glad you found the post helpful.
I can understand your problem and i wish somebody could help you in this regard.
Let’s hope someone on this forum listens to your request and builds this project for you.
By the way, if you search amazon you should be able to get such products ready-made also.
Hello Swagatam,
I’m interested in understanding how an MPPT really works.
I’ve studied the circuit https://www.homemade-circuits.com/mppt-circuit-using-lm317-ic/
but I cannot detect the part that is making up the PWM in this circuit.
As the LM317 is a linear circuit, that cannot, in my opinion, be part of PWM and will produce a lot of heat.
Can you please destroy my doubts about this part !
Thanks Wolfgang
Hello Wolfgang,
Actually in this concept the LM317 is configured as a switching regulator. Here’s what the datasheet of the LM317 says about this configuration:
Low cost adjustable switching regulators can be made using an LM317 as the control element. The figure shows the simplest configuration. A power PNP is used as the switch driving an L-C filter. Positive feedback for hysteresis is applied to the LM317 through R6. When the PNP switches, a small square wave is generated across R5. This is level shifted and applied to the adjustment terminal of the regulator by R4 and C2, causing it to switch ON or OFF. Negative feedback is taken from the output through R3, making the circuit oscillate. Capacitor C3 acts as a speed-up, increasing switching speed, while R2 limits the peak drive current to Q1. Efficiency for the regulators ranges from 65% to 85%, depending on output voltage. At low output voltages, fixed power losses are a greater percentage of the total output power so efficiency is lowest. Operating frequency is about30 kHz and ripple is about 150 mV, depending upon input voltage. Load regulation is about 50 mV and line regulation about 1% for a 10V input change.
I am curious if you are interested in build/code/test and selling some relatively simple prototype devices PC/arduino (or other such devices – we use PSoC LP5 a lot, but whatever you prefer) prototype devices, for example the timed temperature programmer you described (https://www.homemade-circuits.com/programmable-sequential-temperature/#comments), I will use them some chemical instrumentation research that I do – I used to do this myself but I havent kept up and my students have learned chemistry, its an uphill struggle with a soldering iron or coding. Let me know… (you can get my website by googling my name)
Hello Purnendu,
I appreciate your interest in this field, and I really wish I could help you, however building and testing a prototype practically may not be possible for me at this moment.
I googled your name on internet and found interesting details about you on Wikipedia and other sources.
Thank you so much for commenting in this blog. Please keep up the good work.
Hello, trying to replicate a neon bulb that flickers like a flame. I repair vintage clocks and the click in question has a neon bulb with a 220k resistor that us supposed to simulate a dancing flame. I trued using some new neon bulbs with a new 220k on one leg and I get a steady glow. What am I missing? Do I need a special bulb or? Thanx in advance Greg.
Hi, Please do the connections as shown in the following diagram, it should work:
https://www.homemade-circuits.com/wp-content/uploads/2024/02/neon-blinker-circuit.jpg
I am planning to use a 220 volt induction heater probably 15 kw or 25kw.
I plan to use the induction heater in an unusual way.
I want to use it to heat pipes filled with different chemicals. The pipes will be sealed and heated to approximately 400 f. This will significantly increase the reaction of these chemicals. These chemicals need to cool down before I can remove them from the pipe.
My idea is to heat one pipe at a time. When the proper temperature is reached, I will turn off the electricity to that coil. Then I will turn on the electricity to the next coil in the line.
In the meantime the pipes that have already been heated will have time to cool.
I am not sure how to wire this. I know you can purchase stove top induction cookers with four different burners. I assume all four burners can operate at the same time. Also, they can operate with just one or two burners.
Can this work by going through a series of relays?
I would very much appreciate any advice that you may be able to offer me.
Thank you very much for your help.
I think you can turn ON/OFF the induction heater units through separate SPST switches, a relay is not necessary. The setup can be something similar to the following design. You can add individual ON/OFF switches in series with the supply line of the respective induction heater units.
https://www.homemade-circuits.com/tap-water-induction-heater-circuit/
Topic: Extending the working high voltage limit of a ready-made SMPS.
Low-power conventional SMPS (2A/24V for example) are rated to work between 100 to 240V. Is there a posted circuit which could be added externally to extend their working high limit to 380V?
Please note that I don’t mean just protecting them from a high voltage (by disconnecting them for example).
Thank you.
Hello Kerim,
The working high limit of an SMPS is around 285V RMS that is equal to 285 x 1.41 = 401V
Thank you for your prompt reply.
You likely refer to SMPS units which are different from what our local retailers have (imported from China). At best, they may work up to 260Vrms before they burned.
It seems that your 401V is a peak voltage. I meant by 380V the 2-phase voltage (Vpeak = 537 V)
Ok, but that looks very high, I do not have any circuit at the moment with me , which can control a massive 537v for the smps, a linear regulator can be used but that might heat up a lot.
The input current of such SMPS is relatively small. So, a hi-voltage MOSFET (with a diode bridge) could be made to act like an active hi-voltage zener (about 200V when on). It will be connected in series with the SMPS. It is shorted (actually its lowest voltage drop is a bit above its Vgs threshold) when the mains voltage is below a certain limit (for example, when the instantaneous voltage <300 V, peak of 212 Vrms). And it turns on above it (sine tips). An opto-coupler will likely be needed to isolate it from the mains level sensor which drives its gate.
Yes, that’s right, since the current is relatively small a mosfet regulator might work in a source follower manner.
An isolation might not be required according to me.
https://www.homemade-circuits.com/0-300v-variable-voltage-current/
I wish that isolation is not required.
If I understood you well, the mains instantaneous voltage sensor (to drive the MOSFET gate) and the source pin of the MOSFET can have the same reference node. I personally can’t see how this could be done.
I am actually referring to the following circuit:
https://www.homemade-circuits.com/wp-content/uploads/2024/02/MOSFET-stabilized-voltage-regulator.jpg
Now your solution is crystal clear, Thank you.
I will try to simulate it.
Sure, no problem.
I simulated it. Then I built it to test it with 24V/1A SMPS.
I did it because I was worried about the new lowest voltage limit. Usually, it is 90Vac at full load. First, I tested with a load of 8 // 220R/5W (about 873 mA). The lowest voltage became 115Vac. But it decreases to 110Vac with 6 // 220R/5W (about 655 mA). Finally, by adding 2uF/400Vac at the regulated output, the lowest voltage decreases from 110V to 100Vac. This result seems suitable for my application.
Thank you again for your help.
OK, great, thanks for updating the information. Appreciate it.
It seems I can’t receive notification emails from you (in the inbox or spam folder).
I wonder if you may have an idea on how this could happen.
Thank you.
Sorry, I don’tknow how to solve this, because if I am able to get the test notification then you should be also able to get it. You can perhaps try commenting with a gmail or an Outlook account and check if that works.
It may be a silly question. Should the ‘bell’ button (at the left of ‘POST COMMENT’) be pressed or not to get back an email (I mean for other readers).
What confuses me is that its pop-up text is the same after pressing it.
Usually, the pop-up message tells what will happen if the button will be pressed. And after pressing it, its message reverses too.
The bell button by default is enabled to notify the entered email IDs. If you press it and if you see a cross mark on the icon, that means the notification is disabled.
I just read your reply on the other page (4046).
It seems it is out of our control to let your notification emails reach my inbox. So, I will try to visit your pages, once a while, on which you may reply.
Sure, no problem.
Sometime back, I had posted a question regarding countdown timer with display. You had kindly replied and I had added my response etc. I would like to find this thread again.Can you please help?
Thanks and best wishes!
Hello Dr. KV,
I think it is in the following post, please check it out.
https://www.homemade-circuits.com/best-ic-4060-circuits-and-projects/
Sir, I need some assistance in stimulating a circuit which is ground fault circuit interrupter (GFCI). RV4145 is one of the GFCI’s. I faced problems while simulating a part of leakage current detection. Basically I want to simulate a current transformer (CT). It will detect leakage current of 5mA. The turn ratio is 1:1000. CT primary is line and neutral of the power supply. During normal condition, the CT won’t operate as the line and neutral will cancel out the current. During fault, 5mA current will flow and is sensed by CT. Its secondary will step down the leakage current by factor of 1000. Then there is an IC (RV4145) which has 8 pins. 1. Feedback, 2. NC, 3. V Reference(13 v), 4 Ground, 5. SCR trigger (signal is sent to scr which will trip the relay), 6. +vs (26) here, 7. Op amp output, 8. NC
CT secondary is connected to pin 1 and 3.
What i did is I connected a sinosoidal current source of 5mA tp primary of CT. Then sets coupling factor to 0.001 in proteus which gives 5 uA in secondary. The secondary is then connected to op amp which gives voltage output (which forms op amp output at pin 7). Then two comparators are connected which is regulated by 4 zeners (6.2 V each), and it creates v reference at pin 3.
Please sir can you please provide assistance in solving this. Im new in this and i can’t figure out how to solve this.
Hi Zoya, thanks for asking this question, I understand you want to solve a circuit simulation problem, however since I do not use softwares to simulate my circuits, my knowledge of circuit simulation is not good, so I am sorry i won’t be able to help you in this regards. I hope someone else on this forum is able to solve this for you.
Thank you for the reply. Can you please tell me where i can find such forums. I new in this and i really need some guidance. I hope you understand this. I actually want to use in proteus, where line and neutral will be the primary of CT, and the secondary will give current differential. Please help me in this. My question is similar to this project of your.
https://www.homemade-circuits.com/load-current-control-through-current-sensing-transformer/
I understand your problem, however my knowledge regarding proteus simulation is not good, so I cannot solve it for you. Did you try searching for “proteus related forums” online? Please give it a try.
Sir, I need a simple circuit to detect the flow of water and if there’s no water flow (with time delay) then there should be a buzzer alaram. As I already have a water level controller I wish to connect this to the power supply which is connected to the motor.
With regards
Gargi.?
Hello Suresh, you can try the following concept:
https://www.homemade-circuits.com/wp-content/uploads/2022/11/simple-dry-run-protection-circuit.jpg
Hello Swagatam to both you and your”gang” or team. I’m a highly ki accomplished technician with thorough exp in almost all consumer electronics eqp right from valve,s. But my strength is in analogue and not digital.As I’ve executed many projects for many ppl, I have a core issue in ex a control unit for a small domestic luggage lift that has to be installed in a building of 5 floors. The only issue here is getting the lift to anyone who summons it. The lift should have floor buttons in order to send it to its desired”destination. Ideally the should be only a call button which will summon the lift. “The whole operation of proposed to be hauled by a winch, appropriate counter weights, door alarm, overweight activator, intercom B/w car and desired destination, and everything else which has been already worked out.I need serious assistance in this particular aspect and I will def tell you how it’s panning out. Thought assistance in this cnnx will be deeply appreciated. Thank You Very Much.
Thank you Prasanth, for this interesting question.
What you are asking is actually a full fledged lift operating circuit which might involve relatively complex digital circuit configurations.
Actually I had tried to design a lift circuit before but failed to do it.
If possible I will give it a try, if I succeed I will surely let you know..
Fantastic
It Is 24 V to 400V ( 0-1Amp )
You can try the first circuit from the following article:
https://www.homemade-circuits.com/12v-car-laptop-charger-circuit-using/
It is a CV circuit but not CC. For CC you will have to add additional stages.
You will have to use a 400V zener diode and adjust the inductor coil to get above 400V.
I am in need of designing of 12 V to 24 to 400v ( 1 map ) Boost converter variable CVCC type of supply pls help
Hello,swagatam I want to discuss about 12 volt solar pan type induction . Should I get your cell number ? Thank you.
Hello Shabbir,
You can feel free to discuss it here through comments, if possible I will try to solve it for you.
Hello Swagatam! Happy New Year!
Swagatam, I have long wanted to create a neurostimulation device and I am tormented by the fact that I do not have enough knowledge and experience to create a circuit diagram of my device.
I want to create a TRNS (transcranial random noise stimulator). It uses an alternating current of random frequency (from the range of 100-640 Hz) and random amplitude (from the desired range of -1.5 to 1.5 mA). How to force the current to take this form?
tRNS stimulation differs from tDCS in that instead of constant direct current delivery, current levels are randomly generated, with a Gaussian distribution around a specific mean intensity. Other parameters related to the stimulation electrodes, like position and size, are similar to tDCS.
Do you know what a schematic diagram of such a device might look like?
Thank you Nikita, and a Happy New Year to you too!
I think I may be able to design this circuit.
So it should be basically a randomly varying current source (AC) with a randomly varying frequency, right?
And the voltage range can be anywhere between 10V and 60V, I guess.
Let me know your thoughts on this?
I would really like to share my thoughts on this matter if only I had them. I have much less knowledge and understanding on this issue than you. Therefore, it would be better to entrust this to you.
Probably the most useful thing I can do here is to send links to sites that have information about trns.
https://en.wikipedia.org/wiki/Transcranial_random_noise_stimulation
https://brainbox-neuro.com/techniques/trns
https://ars.els-cdn.com/content/image/3-s2.0-B9780128196410001092-f00109-08-9780128196410.jpg
https://i0.wp.com/www.brightbraincentre.co.uk/wp-content/uploads/2023/03/noise-for-better-learning.jpg?fit=753%2C499&ssl=1 (this shows what the current shape should be)
I am new to electronics and planned to create this device in the future when I mastered electronics well enough.
Ok, got it, thanks very much, I will look into those articles for the related specifications and try to figure out an appropriate design for the project.
I will publish the design as a new post, I will notify you once it is done?
Of course, thank you very much!
Hello Nikita,
I have published the post, you can find it in the following link:
https://www.homemade-circuits.com/transcranial-random-noise-stimulation-trns-circuit/
I need help with a circuit controller. It would help if I could upload a diagram to explain how I want the lights to function, but I will try to explain. This is for 12V DC, 9 LED lights (these are small LEDs, sort of like a side marker light, I do not know the amperage draw). I need an easy to program controller, something like all I have to do is make simple delay/time changes (I am not a programmer), and something I can seal from the weather, and not be bulky for mounting.
There a 9 LED lights, they are to be mounted horizontally (from left to right 1-9). The controller needs to control the lights as such:
All on at max brightness (this would be the start of the cycle), if at start all are at max brightness then they would all need to have their brightness reduced to say 50% ish, Light 1 would increase to max brightness then decreases to say 50% brightness as Light 2 increases to max brightness, then decreases as Light 3 increases and so forth.
After a cycle or two of progressive increase/decrease across all lights (at the end of Light 9), all lights will go to max brightness for a short cycle (like 5 seconds) and then enter the progressive increase/decrease phase. This is a continuous loop. Hopefully you get the idea
Basically, I want the LEDs to give a wave affect.
Your help is appreciated
Thanks for posting your circuit requirement! I will design it and post it in a new article. I will let you know once it is done.
I have tried to design the circuit, you can find it in the following link
https://www.homemade-circuits.com/led-light-wave-effect-generator-circuit/
Thank you very much for the circuit and quick turn-around. Once I get it built, I will let you know.
You are welcome. All the best to you!
Thanx for all these wonderful circuits. Recently my dryer motor burned due to overloading and even fuse cannot save it. The motor is 40W, 220v. B4 buying a new motor, I intend to do some research to have some circuit in series with motor itself so it can detect overload and disconnect it. Please let me of any effective circuit probably with some adjusting customization to fine tune it with motor specs. Thanks and regards
Thank you Sak, You can refer to the last circuit from the following article. You will require a relay control or an triac control to auto cut off the motor when over current is detected:
https://www.homemade-circuits.com/dc-motor-protector-circuit-over-voltage/
I want circuit for break of motor.
In put: 200 VAC, 2 Phase
Out put : 110VDC
Break voltage 110 VDC, 2A
Sorry, I did not understand what you mean by break voltage?
Hi! I m from Turkey.
I need a schematic to control two relays with timer. I saw some schematics at this page. But i couldnt use them. They have some differences. Would you please help me.
The timer has 2 adjust. Toff and Ton.
When I turn on circuit it waits as t-off time. Then relay 1 is on as t-on time. Later r1 is off and waits again t-off time. After that relay2 is on during t-on time….it runs till I switch off.
T off 0-3 minutes
T on 1-5 minutes
…..
Turn on
1 min wait
3 min run R1
1 min wait
3 min run R2
1min wait
………..cycle
Turn off
Hi, I have designed the circuit for you. You can find it in the following link. Make sure to adjust the 100K pot to get 1 minute ON/OFF duty cycle from the IC 555. I think you may have to use a 1M pot instead of 100K for getting 1 minute ON OFF duty cycle.
https://www.homemade-circuits.com/wp-content/uploads/2023/12/two-relay-4017-timer-circuit.jpg
Hi Swagatam I have a Texas Instruments processor that initializes a ULN2003A to switch a GND signal to an opto isolator which already has 12v present which switches a SMPS on . the problem is that according the circuit the processor should send a high/positive signal to the ULN2003A but it sends a GND signal when measured at an input of the ULN2003A relative to the 12v on the opto isolator, As the ULN21003A needs a positive input to initiate a GND output via open collector output.
How can I generate a high/positive signal for the ULN2003A input from the low/GND input of the processor..
BTW there is a brief 1.1V odd measured at the input of the ULN2003A at power on , then the input pulls low or to GND
Hi Andrew, I think the following design will do the job for you.:
https://www.homemade-circuits.com/wp-content/uploads/2012/01/PNP-relay-driver.png
Please ignore the relay and the diode, you can simply use the collector of the transistor to acquire the positive signal in response to a negative or ground signal from the processor at the base (trigger input).
Hi, This is regarding Piano, Guitar Sound Effect Generator Circuit. I would like to understand what exactly the input given to start button. Does it accepts External Audio signal from a Musical instrument from its Piezo Pickup. So that i can get a sound of say Piano, Flute from the Audio signal given from my string instrument like Guitar or Mandolin ? Will it capture and deliver the exact pitch of a musical note as a piano or flute sound given from input Audio signal?
Hi, that circuit is a sound effect generator, it is designed to generate a special note resembling guitar or piano by its own, as per the settings, and in response to the pressing of the start button. It is not designed to accept external frequency inputs.
Thanks for Clarification. Do you have any solution for my requirement. I have seen such a device developed by Roland ( GR-55 Guitar Synthesizer). I know it may be very difficult to develop. I will be happy if i get only violin and flute tone. I intend to use a foot switch to trigger.
Yes, it can be indeed very difficult to design an identical circuit, however I have a guitar amplifier circuit which will accept external signals and amplify it accordingly….I would recommend the second design from this post:
https://www.homemade-circuits.com/100-watt-guitar-amplifier-circuit/
Hi, we have problem of stray dogs in our society and it is getting worse day by day. can I get some ultrasonic dog repellent circuits to reduce the problem? Do these ultrasonic sound dog repellent really work? what is its working range? If I can get some tried and tested solution it will be a great help.
Hi, you can try the second last design from the following article, it is a tested design:
https://www.homemade-circuits.com/dog-barking-preventer-circuit/
Hi,
I’m interested in controling the BP of a 10 gallon pot of beer. I have a hot plate 220v 25A that is manually controlled. I thought at first to use PWM through an opto isolator to a 30A triac. This may be ok but would I be better off trying to use phase angle control like a light dimmer? The on time allowed to be altered by the R adjust; effectively PW modulation. I don’t have clear idea on the best approach.
The triac considered is T3035H. I started off committed to PWM but prior to actually implementing same it occurred to me that I should be treating this as triac’s were intended.
Do you have any suggestions?
Thanks,
Keith
Hi, both the techniques are good and will allow you achieve the goal, however the light dimmer method can be much easier to build and implement. Please let me know if you further queries.
Hello,
I am working on designing a led strip which must operate in the following manner:
Blink—> Blink—>Blink—>Fade ON.
Is there any possible way to achieve this without using any microcontroller IC?
Please help me out !!
Thank you in advance.
Hello,
It may be possible in the following manner, ON-OFF-ON-OFF-ON-OFF-Fade ON.
Could you kindly help me make the circuit. As of now, I have two separate circuits:
1. Blink circuit, using 555 timer.
2. Fade ON part using transistors
But I have no clue how to cascade both the circuits to operate in Blink–>Blink–>Blink—> Fade On.
If there is any other way, I would humbly request you to kindly guide me.
The Blinking effect proposed by you can be interpreted as ON-OFF, ON-OFF, ON-OFF, then Fade ON. This may be difficult to achieve using your two circuits, however it may be possible using an IC 4017 and IC 555 together.
If the above effect looks OK to you then I can provide you with the circuit idea.
Thank you so much for your insights. If you don’t mind, could you kindly help me make the circuit? I would be very grateful.
No problem, I will try to create the circuit, can you please tell me what do you want to illuminate, I hope it is LEDs. If it is LEDs please provide the specifications of the LEDs, quantity, voltage, current etc.
Thank you so much for your support. Yes, I want to illuminate LEDs.
total number of LEDs: 29
Voltage: 2V
Current: 25mA
Kindly let me know if you need any further information.
No problem, you can try the following concept. Make sure to use proper resistors with the LEDs:
https://www.homemade-circuits.com/wp-content/uploads/2023/10/4017-light-effect.jpg
Thank you so much. I am very grateful. I will definitely try this circuit out.
You are most welcome, let me know if you have any further questions.
hello brother, I am an electronic repairer not a programmer, please I need some information from your experience. in this diagram of Arduino 3 phase inverter circuit, my question is that I can change the MOSFETs with a smart power module (FSBS15CH60) because I have many treadmill motor controller boards which have an error on the microcontroller?
tanks
Hello Nassih, I checked the datasheet of the FSBS15CH60 and from its internal schematic it seems the module can be used as the inverter output stage in place of individual mosfets. However, the pinouts of the module will need to be replaced correctly otherwise there can be serious problems.
Hi Swagatam,
I would like to control an 8-channel 12V Relay Module with a normal pulse switch to use on my vehicle. When I checked the parameters the IN1 to IN8 does not have any input specficiation. On some websites, 0 to 1.2 volts but polarity is not mentioned. My source voltage is from 12 to 14.2v max @ vehicle running condition. Product link below mentioned
https://www.homemade-circuits.com/wp-content/uploads/2019/12/hysteresis-in-relay.png
https://www.homemade-circuits.com/wp-content/uploads/2022/06/understanding-relay-pinouts-and-contacts.jpg
Hi Anuraj,
The relay you are referring to is a 12V DC relay, since this value is printed on the relays.
Design#3: DC Motor Controller with Multiple Features
https://www.homemade-circuits.com/dc-motor-speed-controller-circuits/
hi sir i have small clarification required on this relay you given in this (12V/5A) dual channel its looks like two pole contact, please explain me little more about this section.
Hi Pradeep,
It is a DPDT relay. The upper contacts shown in circles are N/O and N/C pairs of contacts. The switch action is shown by the pair of moving contacts of the relay connected to the lower circle which forms the common pole of the relay. When the relay is powered the movable pair of contacts connect with the pair of N/O contacts, and when the relay coil is not powered the movable pair of contacts connect with the N/C pair of contacts.
In the circuit this relay is used to execute the reverse/forward rotations of the motor.
I read your excellent article about heating element control with triac.
I would like to make a control of a 230V ceramic heating element (5-10watt) with a BT136S 600D triac and an ATtiny as a pulse generator. How do I calculate the pulses so that I can change from 65C to 80C in four steps?
I’m thinking of controlling it a with a push button and some LEDs for indicating temperature. Can you help?
Thank you Flemming,
Can you please show me the link of the article so that I can check it out for the details?
Sorry late reply, I’ve been down with corona, but are fine now. I just searched, heat and triac, and read what was there…. So I thought I maybe could reach out to you for help. I only know a little about electronic circuits.
What is the input voltage like, is it AC 220V or 120V? If yes, then I would recommend you an ordinary triac based light dimmer circuit as explained here:
https://www.homemade-circuits.com/how-to-make-simplest-triac-flasher/
I’m wondering about a delay on, then delay off circuit, with no button, 5v DC. I have a usb port, I would like to power on a linear actuator ~5 seconds after the USB port supplies power to my circuit, then turn it back off after ~0.5 seconds and remain off until the USB port is powered down, then repeat the cycle when the USB port is powered on again.
You will require a two stage programmable timer circuit for this application, as explained in the following article:
https://www.homemade-circuits.com/how-to-make-simple-programmable-timer/
Good afternoon!
I’m a complete amateur, who took a micro-electronics class in high school. I now have a deaf son that has recently started school. He has a tendency to make a lot of noise because he can’t hear himself and he can be a disruption to the rest of his class. I would like to make a noise visualizer, that would allow him to self correct because he can see when he is making noise. I came across this post (https://www.homemade-circuits.com/simple-audio-spectrum-analyzer-circuit/) and it seems like this might be what I need for this application, but want to confirm that there is a chance this will work for what I need before I invest too much time or resources into building this project. Does it sound like this is the correct circuit for an application like this? Thank you!
Hello Tom,
I would rather recommend you the following circuit which is a tested design and looks more relevant to your requirement. Hope it does the job for you.
https://www.homemade-circuits.com/wireless-music-level-indicator/
Hi Sir,
I am given a project to design a Printed Circuit Board (PCB) for a power factor correction circuit for a single-phase load using all required power and electronic components. Can you please give me a circuit for this design and ideas to proceed further.
Thank You
Hi Tashi,
Sorry I do not have a PFC circuit with me right now, however I think you can find some important information in the following article:
https://www.onsemi.com/pub/Collateral/HBD853-D.pdf
Hi looking for large motor activated by an phone
Hi, you can refer to the following post:
https://www.homemade-circuits.com/gsm-pump-motor-controller-circuit-using/
Hi there mr. Swagatam, I want to convert a 2-0 volt signal to a 4-20mA current signal, the sensor needs 5VDC power and the output signal should be 24VDC. I’d need to flip the signal and convert it. what would be the best way of doing this?
I was thinking of using 2 non inverting opamps, one as a buffer and the other to increase the span of the signal, maybe 0-10V. My issue is just to convert the voltage signal to a reliable 4-20mA signal.
What do you think is the best voltage to current conversion circuit?
Hello Gerhard, are you trying to convert a 2 V into 24 V (4 – 20 mA) signal? What is the current capacity for the 2 V signal?
Hi again,
About 998EX sensor and delay circuit, I forgot to mention that I need this delay circuit to be simple and if possible with npn transistors or N mosfet.
I am very grateful for the content of your website, and I have refreshed my knowledge with the explanations that you offer of each published circuit. My best regards for the great work you do in favor of the world of electronics.
Thank you so much.
Hello Sir, i need help with a delay circuit,
I want to use an ADEMCO 998EX infrared movement sensor so that when it detects movement it activates a relay for a period of 3 to 5 min. This sensor works as follows: it has two output terminals to notify the detection. This output is normally open when the sensor is not connected to power, and when the sensor is powered with 12v, it takes 1 minute to balance the temperature it senses in the place (during that minute the output remains open) and then, it changes to activated waiting for an infrared movement (in this state the output changes to closed and showing 1kohms between its two output terminals). When the sensor detects any infrared movement, the output changes to open for 2 seconds, and returns to closed waiting for another movement detection. Internally, the sensor has a SPARTAN SIP REED NormallyOpen relay (COTO 9007 series 4 terminals) with a resistance of 15 ohms in series on one of its output pins. It also has two common diodes, each one with the cathode attached to each output terminal respectively, and their anodes attached to the negative of the circuit. I think they are for protection.
I need a circuit that detects the open condition of the sensor output, and in response, activates a relay for 3 to 5 min with a buzzer. The buzzer should be kept active during that time even after the sensor output changes to closed again. After the 3-5 minutes are over, if the circuit detects the open output condition of the sensor again, it repeats the activation of the buzzer during the 3-5 min again.
Hello Victor,
I think you will need an IC 555 based monostable timer circuit for the mentioned application. A transistorized circuit might not give proper results.
Greetings Sir Swagatam,
I am glad that I have found your website. I am searching for information regarding GridTied inverters and would like to ask for your expertise in explaining the circuit diagram (I have traced it from a defective unit). Is there a way that I could send you the diagram via email? Would really appreciate your feedback.
Hello Dexter,
I understand that you want to learn the details about a grid-tie inverter schematic, however honestly, I don’t think I would be able to help you because grid-tie inverters are very complex projects and I do not have specialized expertise in this field. Still, if you want me to give it a try you can upload the schematic to any free image hosting site and provide me the link here I will check it out and see what I can do?
Hello Sir, Only this particular circuit that am trying to understand its function. This is actually the GTIE (DC-AC) inverter output that merges with the grid. Alright, I will take your suggestion and thank you for replying.
Sorry Dexter, I am having difficulty in understanding the schematic, because it doesn’t seem to be in proper order. Where are the opto-coupler LED connections going? I guess the opto-coupler LEDs should be connected with the mosfets and the SCRs must be integrated with the grid line?
I am not sure, I may be wrong.
Sorry if my schematic is sort of confusing but the optocoupler LED goes to another section of a MCU (with code embedded) that controls inverter phase matching. The mosfet along with the scr that outputs the generated ac voltage back to the grid is where I get lost. Is the mosfet along with the scr a valid circuit do you think?
It seems the mosfets are switching the DC supply across the SCRs, but i can’t figure out from the schematic how this is being implemented, even I am lost. Moreover once the SCRs are triggered ON, they are going to get latched and the gate synchronization from the opto-couplers might have no effect on the SCRs.
You are absolutely right that grid-tie inverters are very complex projects. Just to give you an idea about the circuit am trying to learn and demystify: https://ibb.co/VThbV8z
Am so grateful for the time you spent helping out. Will keep you posted.
You are most welcome, I hope you will be able to solve the issue soon.
schematic for your expert review and thanks =)
https://www.homemade-circuits.com/wp-content/uploads/2023/08/Gridtie-inverter-output-stage.jpg
Hello Sir,
I hope all is well with you,
I am interested in your website and I want to publish my article on your website.
Can you add my article?
Please let me know your terms and conditions.
Waiting for your reply.
Many thanks.
Hello Fannii,
The terms and conditions are simple.
The post should not have any external links.
The article should be regarding a circuit idea with a circuit schematic.
Hi, I find your website very informative and enhance learning. Are you open to business cooperation? Feel free to contact me via email. Thanks!
Hi, glad you liked the website, however presently we are not open to guest post submission or any other business format.
Hi sir,
Sir I’m having these small MacPower inverter with 42000mah (155wh) rated, I need to know if I can use 12v 50w solar panel for charging it, the dc input of the inverter is 15v 2A, and one more thing, I’m about to replace the lithium battery inside, hope these is okay?
Hi Tunji,
for a 42 Ah Li-ion battery the optimal charging current should be around 20 amps, but your solar panel can supply a maximum of 50 / 12 = 4 amps which is too low to charge the battery.
Moreover a 12V panel output will not be able to charge a 15 V battery.
OK sir but my charger is rated to be 15v/2A, what can I do sir, and thank you so much for response
Tunji, 2 amp current is very less for a 42 Ah Li-ion battery….it might take 2 days for the battery to get charged.
One more thing sir what can I do with a 200w solar panels 12v rated, 20amp battery and 640w UPS Sir, or do I need to construct my own inverter?
Tunji, You can use the 200 watt panel output to charge your 20 Ah battery. The UPS can be modified to convert it into an inverter.
Thank you so much sir and God bless you sir
You are welcome Tunji!
I am looking for a timer circuit that can be an electronic replacement for a motorised freezer defrost timer. A motorised timer uses a synchronous AC motor and gears that closes output contacts for a short time, typically 10 minutes, to put the freezer into defrost mode.
What an electronic circuit would need is a long timer with a short output event. Ideally 24 hour cycle time and 10 minute output switch time. Timing accuracy and stability would not be crucial, and the event output of the timer could control a relay for switching 240V AC for a defrost heater.
I think a programmable PIC or Arduino project may be one solution, but I have been searching for a discrete components circuit for some while without success.
I appreciate your circuits advice, which are very good examples. I wonder if you have any thoughts on how to make such a long timer.
Kind regards,
Malc
I think the first circuit from the following article will do the job for you:
https://www.homemade-circuits.com/how-to-make-simple-programmable-timer/
Hi,
I am anjali, manufacturer of PCB for Diwali decorative series led.
I am sharing you the image of our PCB and Video of Series in which it used.
Can you please tell me which Code/Number of IC used in this kind of series.
Right now i am purchasing this IC from other which is very costly for us. Please help me.
https://drive.google.com/file/d/1Tn3Qu8w4HxEQjmeQ5dkNktiYdxHEqPA6/view?usp=drive_link
I am not able to attach image, please contact me.
7383269949
Hi,
the google drive link is not giving me access to open the link here because it is not in the sharing mode
Re: Make this Insect Wing Signal Detector Circuit
I am looking at enhancing this type of circuit with a custom tuned coil (receiver) that I have specification on. Can you please contact me to email more details?
You have a great grasp of analog circuits.
Would like to run a couple of specs past you (with diagrams).
Best Regards
Sorry, I wish I could help you but unfortunately I do have sufficient information about this circuit as this circuit was contributed by an external author.
I am considering making a small number of circuit cards (simple ones like in the Insect wing detector. Is your company, hobby, or shop available to take bids? Or do you have any recommendations?
I am old enough, eyesight, to have given up my soldering iron. But, have some small projects and budget.
I wish I could help you, however presently due to lack of time I am unable to accept eternal job offers.
Hi Mr Swagatam !
I need to replace a big and heavy isolating transformer (primary 220V / secondary 220 tap 110V / 1kw ) for sometrhing like a SST (Solid State Transformer) .
Do you have any recommendations on that ?. I couldn’t find anything practical!
Hi Oswaldo, sorry, I do not have sufficient information about this concept so I can’t figure it out for you….
I would like to make a small induction coil for heating water in a cylinder. I am not an electrical engineer so I would not really be able to figure it out. I was not even to understand the parts list in your project above LOL.
Maybe you could build one for me? I would be happy to pay you.
I won’t recommend you to build this circuit, instead you can easily buy a working kit from amazon and use it for your purpose.
good day
i am looking for simple circut design where i can plug an input and the unit will count the beats per minute and display result digitally.
Hi, sorry, I do not have this specific circuit with me that this moment, If I find one will surely let you know.
Thank you for your circuits, I intend to build your Crystal Set with LOUDSPEAKER Circuit and, I would like to add an On/Off Switch with a Led to show when On and Off. Could you please show me where the best place is to fit the switch and led in the circuit also, I presume I would need some resistor ???? inserted to protect the led ? /Also, I intend to use ceramic caps for C1 and C2. is that acceptable? and the 4k7 is just a volume control pot I presume?
Hi, you can put the switch in series with 9V supply positive line. The LED can be put across the +/- lines of the 9V supply with a 1K series resistor.
https://www.homemade-circuits.com/crystal-radio-sets-with-amplifier-circuit/
Yes you use ceramic capacitors for those C1, C2. 4k7 is the volume control pot.
For further questions please post under the above article.
hi.
I presently have some solar panels that are between 33 and 35 Volts each. currant is 8.1 amps I have 2 strings of 6 giving a max currant of 16.2 amps into my inverter. I want to do a DIY hybrid system by charging 10X car batteries in series during the day and applying the stored DC onto my inverter in the evening. charging is.not a problem, but, I need to limit the currant from my 120V battery to the maximum the inverter can handle as it is designed to not have very much available to it in the first place. giving the inverter a potential 500 amp supply is a bad idea. I also need to limit the amps in order to generate watts I am using and to not export to the mains, KW, that I uave spent the day accumulating. so. we are looking at 120vdc but could be up to a maximum of 500vdc and currant limit maximum of 16 amps with ability to choke down to a low level say one amp. without getting too hot so as not to waste energy.
Hi,
I have a few current limiter circuits posted in the following article. You can probably try the MOSFET version and check the response. Make sure to upgrade the MOSFET and the BJT specifications to match the high voltage spec of your application:
https://www.homemade-circuits.com/universal-high-watt-led-current-limiter/
Swagatam,
Here’s a poser for you … have a display with 27 opaque plastic candles, with a small circuit inside, using a 556 to make a small filament bulb flicker. In the base
of this unit, there’s a 15v/4A switching P/S. Each candle has a pushbutton switch on the top to ‘light’ the candle.
There is a coin slot. On the underside of the alum plate with the slot hole are two sets of IR transmitter/receivers to detect the coin drop. This feeds to a small p.c. board with a ‘master’ 555 timer ckt. The idea is that once the coin is dropped, the circuit is energized so one or more ‘candles’ can be lit. I believe the master 555 circuit may be a timer so that after the elapsed period, all lit ‘candles’ are put off.
I have no schematics; the date codes on some of the components date back to the mid-80s. The IR devices glued to the underside of the plate have been broken off due to malicious mischief, and a TIP120 on the 555 board has been shorted … the board has suffered some damage.
Given the age of the components, the lack of schematics, I am charged with making this unit OK again. I do not ‘speak’ ARDUINO or other modern microcontroller. And, doing a part # search I’ve come up empty looking for these individual IR components. Any suggestions are gratefully appreciated.
I’ve thought of a BASIC STAMP solution or using an inexpensive PLC controller, both of which I have vast experience, but I would need a RTC settable to some definable long duration …. 15 mins to 1 hr.
I did see your egg timer solution at one point, just use the ‘front end’, eliminate the oscillator & speaker section.
Thank you.
Hi Karl,
Are you looking for the infrared proximity detector circuit, which will detect the coin and trigger a monostable. It is not difficult, it can be redesigned.
Hi Swagatam,
I have a problem with my BTA-41 dimmer where the variable resistor has already been replaced twice, due to damage. It was damage when I used it to regulate 10A step down trafo for batt charging purpose. Does it matter with schematic itself or bad quality of the VR? Can you Please advice?
The schema: https://drive.google.com/file/d/1FrBaadzMpfuSE14VfRdKf3VLS95GUqoI/view?usp=drivesdk
Thanks.
Hi Awak,
Your VR is protected by the series 4k7 resistor so it should not get damaged. You can do one thing, put the lamp in series with the LIVE wire before the bridge rectifier and check the response. Alternatively you can try by modifying the following design and check how it works:
https://www.homemade-circuits.com/wp-content/uploads/2012/04/simpletriaclampdimmerswitchcircuit.png
Thanks for response.
How many watts of lamp? And what kind of response should I check?
Thanks.
In your original diagram I can see a lamp connected on the right side of the circuit, use the same lamp and connect it in series with one of the input wires of the mains AC supply. With a load in series at the input side the VR will not get damaged, or you can try the circuit provided by me earlier.
Ok I’ll try. But fyi, this dimmer has been used longtime with my fan, has no problem, but when used for battery charger, it is damaged.
Actually using a mains AC based dimmer is strictly not recommended for charging batteries, your battery can also get damaged.
Can you please recommand the circuit for regulating battery charging? If has, a simple one.
Thanks.
What is your battery voltage and Ah specification, and is it a lead acid battery?
12V 10Ah. Yes.
In that case you should use a simple LM338 IC based power supply to charge your battery. Set the maximum charging voltage to 14 V and then you can safely charge your battery without any issues. The maximum current must be controlled to 1 amp, and input DC can be from an SMPS or a transformer based power supply. The input voltage must be around 16 V to 18V. Here’s an example diagram:
https://www.homemade-circuits.com/wp-content/uploads/2023/05/36-V-high-current-solar-regulator-circuit-with-adjustable-current-facility.jpg
Hello.I want to design the pcb file of this circuit..but I need calculations for board thickness.track thickness.distance between tracks and number of coils..please guide me
Which circuit are you referring to?