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1. I want a circuit that will automatically allow dc 12v to flow off/on using LDR .
2. 1 want an automatic switch that will always turn on/off ac 110/220 using LDR.
You can explore the following page for more information:
https://www.homemade-circuits.com/how-to-make-light-activated-day-night/
Please, I want you to construct a circuit that can light up and charge a solar street light.
I am having difficulty in getting the main controller. Most of the lights I have are dead and no parts to fix them. I have sent you the picture of the solar street light for you to know the size of the solar light. It has 16 bulbs.
Looking forward to hearing from you soon.
Thanks.
Hello Elisius,
You must provide the complete technical specifications of the solar lamp LED, and also the street lamp. Just an image might not help!
Mr Swatagan , thank you so much for your prompt response.
The solar street light is a 200watts solar, Please ,I would like you to explain to me the more what you meant by technical specifications .
I sent the picture of the solar street light to your email address
. The picture might be of help for you to know the specifications.
Elisius, The picture does not have any information regarding the lamp voltage, current specification.
Please provide the voltage specification of the lamp module and the solar panel, and the functioning details of the controller.
a learner will always stress a teacher, now my question is how can we make a radio call or a walky talkies
For a walkie-talkie circuit, you can explore the following page:
https://www.homemade-circuits.com/?s=walkie+talkie
I want to make to make a small toy house for children to play with 5 foors, but I want to make a lifter using small DC motors found in old DVD players , please help design a the lifter circuit and technic movement design.
What should be the specifications of the movement?
the movement of lift or elevator should be up and down only for example when it leaves down to the second floor it stops for some small time then it continues to the third floor, until it reaches up, then it keeps coming back down while stopping stopping till it reaches down and it will begin going back up again thank you
Ok, I will try to figure it out soon, and let you know…
the movement should be from down to the up floors then down but I don’t know how you will even make the switches
So it will be a continuous up and down and up movement?
the movement should be if a switch is switched for it to go to the second floor it should move from down to the second floor and swagatam please let’s make it almost like a real lifter as long as the switches shall be outside and we shall not make a door for it
Making the movement like aa real lift is extremely difficult, because it will require a lot of coding and can be perhaps be done only through a microcontroller.
I saw a village solar street lights of 40w LED you had made, but please draw for me a design that will use a 7ah/12ah battery with a small solar panel like 10w or 20w solar panel with very good power saving, please draw it without automatic turn on, and the other please draw it with automatic turn on either with relay or without relay. Please make a design of LED either 40w LED or 30w led or below for that village solar street light
Hello Rashid,
Please post this question in the following article, i will try to solve your problem:
https://www.homemade-circuits.com/3-simple-automatic-street-light-circuits-explored/
Hello swagatam, I saw one of your post of making a solar charge controller of 10w solar panel and 7ah battery, so I wanted to confirm if I could use a 12ah battery and the controller would still work well, to be honest can a 12ah battery light 2w bulb or 4w bulb for 12 hours?
The second question is I’m requesting you to make a diagram for a 100w solar panel charge controller minus using a relay please that can charge 70ah battery?
Hello Rashid,
Please post this question in the following article, i will try to solve your problem:
https://www.homemade-circuits.com/3-simple-automatic-street-light-circuits-explored/
Good evening i am very new to Electronics but very willing to learn. i was bought a 3 candle garden light with each candle being powered by x3 AAA 1.5v batteries in series i believe. They currently have a wire from a positive to an LED and the a wire from the other wire to one side of a switch and the a wire with a resistor or some sort to the negative of the third battery.
i would love to be able to convert these to solar so I’m not replacing batteries every week. I sort of understand the circuit diagram but I’d like to make a circuit board with the relevant resistors, diodes and dark/light thingy. i can solder very basically so if given a diagram or better still a step by step diagram that would be great. i have 4.5v solar panels and 6v ones? I’d lime to use the battery holder it comes with which holds the batteries in series if possible? i can send you an email pic of the candle if that helps?
Good morning, and thanks for your question.
I think the first circuit from this article looks the most suitable for your application:
https://www.homemade-circuits.com/simplest-automatic-led-solar-light/
You can remove the shown LED and its series resistor and replace them with the wires of your LED candle.
If you have any further questions, please feel free to comment under the above garden light article, I will make sure you succeed with this project.
Hi sir, can you give me a diagram for charge controller for 24v lead acid battery using solar panel? This is my final requirement of my subject sir i badly need it :(.. thank youuu
Hi, Hughian,
Can you please tell me the Ah rating of the 24V battery, I will to provide you with a proper circuit…
hi sir, I got 15Ah rating here.
I got two 12v lead acid battery here I will connect them series to get 24v , because my prof said it need 24v and there is no available 24v in the online shop so I ordered two 12v instead.
Thanks Hughian, for the information, do you have any specific requirement in the charger design, like automatic cut-off, trickle charging etc.
Hi sir Swagatam,
I just want the circuit an indicator if the battery is fully charge an LED diode will light to indicate it is fully charge, I ill just use my multimeter to manually check the battery voltage if it is low then I will charge it again and LED diode will turn on if it is fully charge. thanks sir.. 🙂
Thanks Hughian,
You can try the following circuit:
https://www.homemade-circuits.com/wp-content/uploads/2024/10/24V-solar-battery-chaarger-circuit.jpg
Please adjust the R2 to get 28V across the battery output points (without a battery connected)
Adjust the R4 preset so that the red LED just switches ON at this 29V.
Hi sir Swagatam,
Sir thank you for that diagram I have a question sir this transistor beside R3, is a NPN transistor? If it is NPN what model is that transistor? Thanks Sir
No problem Hughian,
You can use a BC547 for that transistor. It is a current limiting stage which will limit the output charging current to 1.5 amps suitable for the 15 Ah battery.
Hi sir Swagatam,
thank you very much sir, ill update you if it is working in my part. thanks <3
Thank you Hughian. all the best to you!
Hi sir Swagatam,
My classmate ordered 18V and 30 watts of solar panel, is it applicable to the circuit of the solar panel we ordered? Because the solar panel specs you provide is 35V. Thanks you very much.
Hi Hughian,
18V solar panel cannot charge a 24V battery, you will need a 35V 3 Amp solar panel for charging a 24V 15 Ah battery. 18V 30 watt panel can be used to charge a single 12V 15 Ah battery.
Hi sir Swagatam,
thank you sir for the reply. sir.
You are welcome Hughian….
Hi sir Swagatam,
Im back again 😅 , sir my teacher says it will be best if the charge controller is MPPT, and i honestly do not know what is that. If there is any to modify the circuit diagram you provide to me sir..
Regards,
Hughian
Hi Hughian,
I think your teacher would know better regarding the MPPT specifications and working which he/she wants you to implement, so you can ask your teacher to provide more information about it.
You can also consider trying the following design for the intended MPPT charging method:
https://drive.google.com/file/d/1oYdpFeBemVi_rT8oouiQjs7C_MdGLqjd/view
The previous circuit using LM338 cannot be modified for an MPPT charging.
Hi sir Swagatam,
Thank you very much sir.
Regards,
Hughian
You are welcome Hughian…
Hi Swagatam!
I have built the 15Amp voltage regulator as per the demo circuit given on p.19 here:
https://www.ti.com/lit/ds/symlink/lm338.pdf?ts=1729104861851&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FLM338
I am assuming the LM358 opamp is to blame for it not working, because it is apparently not as sensitive as the offset input voltage of the LM307.
However, looking at the circuit above, I do not understand how it works. Why? Because the adjust pins of the two opamps with 2k Ohm do not get routed to the output of each regulator like they normally do. Do you think I should invest in a LM307 as per the diagram, or perhaps there is something I need to change in the circuit design?
Any insights would be most gratefully received.
Kind Regards,
Bhakti
Hi Bhakti,
In that circuit the opamp is configured as a voltage regulator which senses the output and limits it as per the adjustment of the potentiometer. This information is sent to the base of the PNP emitter follower which adjusts the LM338 ADJ level accordingly.
Actually, there’s no need of the opamp stage, you can put all the LM338 directly in parallel and use them, as explained in the following article:
https://www.homemade-circuits.com/how-to-connect-lm338-ic-in-parallel-to-increase-output-current/
Alternatively you can build a 15 amp regulator using a single LM317 and a 50 amp power transistor, as shown in the following diagram:
https://www.homemade-circuits.com/wp-content/uploads/2023/05/LM317-boost-current-charger-circuit.jpg
You can replace the 2N3055 transistors with a single: MJ11032
HI Swagatam!
Thank you for your prompt reply. Is it possible we are looking at two different circuits? The one I built has no PNP transistor but is the same one you documented here:
https://www.homemade-circuits.com/ic-lm338-application-circuits-explained/#15_Amp_Variable_Voltage_Regulator_Circuit
One reason for building it was an excuse to see how opamps work in different situations.
However, if I can not get this to work, I will just keep the 0.1Ohm 10w at the three LM338 output pins and cross my gingers that this “ballast” solution will work. It will be interesting whatever happens 🙂
Thank you Bhakti,
I may have mistakenly referred to another design of a 15A regulator which uses an op-amp and an PNP, in the datasheet.
In the following diagram which you have used, the op-amp is used as current sensor, when the current across R2 exceeds above the max capacity of the lower LM338 (5 amps), the opamp output goes low and activates the upper two LM338 ICs which provide the extra 10 amps to the load.
https://www.homemade-circuits.com/wp-content/uploads/2012/04/LM33815Avoltageregulatorcircuit-1.png
The output resistors can be eliminated for the parallel LM338 ICs, if you mount all the ICs over a single common heatsink, very close to each other.
Hi,
After I built this one with no PNP:
https://www.homemade-circuits.com/ic-lm338-application-circuits-explained/#15_Amp_Variable_Voltage_Regulator_Circuit
…I could not see it working. It is possible that I have not thrown enough current at it to make all three LM338s start to work. The LM338 configuration seems quite “unorthodox”. It does not involve the typical 240 Ohm between Adj and Out pin. I decided to experiment by isolating the behaviour of the LM338 with just a 2k Ohm between Adj pin and Gnd. And sure enough, with high resistance like 100k, the LM338 Vout was at a maximum, but when around 2k Ohm, it was just a couple of volts.
Not happy I was learning effectively about opamps, I saw this circuit which maybe similar or same as the one you first described:
https://www.homemade-circuits.com/wp-content/uploads/2024/10/LM338-in-parallel.jpg
Well this interests me, because I can easily see how the opamp is sensing changes in the final Vout. My thought is that it increases the final Vout when there is a heavy load on the final Vout, so that the Vout voltage remains the same? But maybe it has more to do with the balancing of the numerous LM338 which are incorporated in this design? I also don’t see the need for a BD140 PNP when there seems to be maybe only 10mA going through it ( 1.25v / 100Ohm).
Hello Bhakti,
In the following circuit, the voltage across R2 must make the pin#2 of the opamp higher than pin#3 by 0.2V, only then the opamp output would go “LOW” and that would trigger ON the upper LM338 ICs. In short, the voltage
https://www.homemade-circuits.com/wp-content/uploads/2012/04/LM33815Avoltageregulatorcircuit-1.png
You can calculate the minimum load current required for this using the following equation.
I = 0.2/R2
However, for this the pin#3 must be referenced at 0.2V also, which is not done??
Also, you are right, the ADJ pin of the upper LM338 must be coupled with the lower LM338 for the upper LM338 to correspond to the voltage levels set by the lower potentiometer, otherwise the circuit will not work correctly.
So it seems the above circuit has serious issues, not sure how this was included in the datasheet of the IC
The other circuit which you provided is correct, you can use try that.
Hi, I use w1209 thermostat in my egg incubators. Have purchased over thirty from very cheap to expensive, none work. Sending them back costs more that I paid for them in most cases. Have schematic, photos of both sides of PCB, but no gerber file to get some made by PDB makers. Is there anywhere I could find a geber file for w1209 PCB? Thank you for taking time to read this.
Hi, I understand the problem you are facing, however unfortunately upon checking I too could not find any online source that provides the PCB details for this project.
Greetings Swagatam,
I stumbled on your site while searching for diagrams for generating electricity from the Atmosphere. I currently have a simple small circuit with a few Capacitors and Diodes to generate 1.5VDC but the current is low and voltage is not sustainable with a small led. My main focus here is “Free Energy” as I use that term freely. I know you have posted many circuits and articles about similar subjects but I would like to build a working model that produces continues voltage with a small load. Over-Unity has also been talked about for some time now but it’s really hard to find diagrams of a true working model to build. So, if your able share a Project I could build at home that is sustainable I would love to try and build it to prove “Free Energy” is truly possible.
Thanks,
Sal
Hi Sal,
Have you tried one of the concepts from the following article?:
https://www.homemade-circuits.com/how-to-collect-free-energy-from/
Actually I haven’t tried these concepts practically, so confirming the results may not be possible for me at the moment.
However, I am aware that the key elements in these circuits are the antenna and the grounding (earthing) which must be perfectly done.
The antenna must be as long as feasible and totally isolated from the ground, while the ground or the earthing wire must be thoroughly inserted into the soil, as deep as feasible…
I want to make a motion activated rat trap using 12v power supply, a 12v pir and a linear pull solenoid. It needs to be basic as I know very little electronics. Can you draw a circuit please.
You must know the basics of electronics and how to solder, if not then you must first learn it and then I will provide you with the circuit diagram…
Hello teacher. I need your help. I need a basic electrical circuit diagram of a step-down convector DC-DC Step Down SKU 7915. Can you help?
Hi Valera, sorry I could not find any online information regarding the IC SKU 7915….
Alternator generator with a DC motor set up. While I am im the beginning brain storming phase, How would you stop it safely without causing injury to yourself of the device. In case I want a portable one for camping or leaving my house for several days.
Hi, sorry, I could not understand what type of safety measure are you referring to? Can you please elaborate.
Hello Teacher. I received your circuit diagram for L4975A. It indicates an input voltage of 35 volts. Should I first use a voltage divider to bring the 50 volts to 35 volts and then feed it to the microcircuit? Or can I immediately feed 50 volts to pin 9
Best regards, Valera
Valera, The L4975A IC’s maximum input voltage is 55V, so 50V can be used in the following circuit:
https://www.homemade-circuits.com/wp-content/uploads/2024/09/L4975-adjustable-0-to-25V-5-amps-power-supply-circuit.jpg
I received your letter and the diagram. Where is the voltage divider or variable resistance instead of the divider? And one more question – how to determine the internal resistance of a diode floodlight
The 10k preset in the previous diagram is the feedback resistive divider.
Sorry, I am not sure how to determine the internal resistance of a diode floodlight.
Hello Teacher. I purchased L4975A and as you promised I will try to provide a circuit diagram for 4975 with feedback, to obtain a stabilized voltage of 17 volts with a load of 3 amperes. The load is a spotlight and it is desirable to take into account the power dissipation of the microassembly
Hello Valera, you can try the following circuit:
https://www.homemade-circuits.com/wp-content/uploads/2024/09/L4975-adjustable-0-to-25V-5-amps-power-supply-circuit.jpg
sir
I am from Thane ghodbunder road,
wish to visit you.
please if possible spare few minutes for me!!
Hello Bhupendra, Do you have any circuit related question? In that case you can feel free to communicate with me through this commenting platform, I will try my best to solve it for you. Please let me know!
As a model railroader, I have a crossing gate that needs to stay activated through a six-foot zone, and stays activated as long as a train remains in the zone. Could I use a six-foot piece of metal track or maybe a copper wire as a sensor plate with one of the circuits described in this article? Cars are mostly plastic.
Thanks for your question, could you please specify which circuit diagram you are referring to? I will try to figure it out for you…
hello sir,
fi am working on lvdt project.i am using peltron lvdt for measurement .As per the datasheet power supply is 3.6 vrms at 3KHZ and the output is +- 1.2v rms . my requirement is precious 3.6vrms at 3khz generator circuit and for the output i require precious rms to dc convertor circuit. Pls. suggest circuit for this project. thank you.
Hello Sridhar,
You can try any of the transistorized version from the following article, and adjust the relevant RC components for getting the desired effects.
Since your input is 3.6V, only transistorized circuits may be suitable.
https://www.homemade-circuits.com/simple-sine-wave-generator-circuits/
I constructed inverter circuit using irf9540 & irf540, it works perfectly with 12volts transformer. I need to use 24volts or 48volts transformer with the same circuit. What should I do. Thanks indeed.
If you are using P-channel MOSFETs in your H-bridge design, then I am afraid you cannot use a load voltage higher than the Vcc supply voltage of your oscillator IC, unless perhaps you use a boost converter at the oscillator outputs.
Hi Swagatam, I saw your article about a wireless charger (Wireless Charger) and I thought it was great and perfect for my university project. I was wondering about the gauge of the 2 core speaker wire used for the Transmitter and also the gauge for the Receiver.
Thank you Robert,
Sure, you can use it for your university project.
For the transmitter you can use any standard two-core flexible wire as shown in the following image:
https://www.homemade-circuits.com/wp-content/uploads/2015/09/wireless-battery.jpg
For the receiver the wire can be a 0.5mm super enameled copper wire.
Please let me know if you have any further questions.
Thanks for the immediate response! Ideally, how many turns should the Receiver coil be? And what should its ideal diameter be?
Actually the receiver coil can be exactly identical to the transmitter coil, however you can experiment with it to get the most optimal results. It might require some experimentation until the right number of turns and diameter is achieved.
It must be noted that the current output from the receiver coil can be significantly lower than the input current to the transmitter coil, and will be directly proportional to the distance between the Tx and Rx coils.
If the current from the receiver coil is not sufficient, the mobile phone might not charge properly.
Make sure the current to the transmitter coil is at least 3 amp, @12V
Hi, your circuit works like a charm! Right now the only problem that I have is that the out is fluctuating. What can I do to stabilize the Voltage and current output of the receiver coil?
That’s great, glad it is working.
To stabilize the output, please connect a 2200uF/25V capacitor right across the output terminals of the 7805 IC.
Would it be possible for you to send a 10 second video clip of the result to my above emails?… if not, no worries.
Sure! I’ll send the video through your email.
Ok, thanks so much…
Can you recommend an inexpensive place to have circuit boards made? Not for a production run, just one at a time. Thank you!
For the single PCBs the cost can be immensely high, no matter which supplier you choose.
Instead of a PCB I would suggest you to build the prototype over a strip-board.
It has been a while since I etched a circuit board, but I think I still can. It will be much cheaper than having one made. Thank You!
You are right, etching a PCB yourself can be much cheaper and interesting also.
Hello Swagatam, I recently bought a stabilizer Model: URZ3412 – 1000 VA
Input: Voltage range 145-260 VAC
I live in the UK and I need 230-235v. The problem is the stabilizer is set to 260V. It has internal settings but I don’t have its diagram. How can you help me. Thank you. N.C.
Hi Niki,
Unfortunately without a schematic it can be impossible to know which preset setting must be tweaked to adjust the high voltage trip level. Randomly testing the presets can be dangerous, so a schematic is necessary.
Hi Swagatam,
Looking for a circuit that opens a door (motor positive direction), then, upon reaching a limit switch, reverses (motor negative direction) to close again (limit switch ends the cycle). Just using a one-button, start process. Liken this to a garage door that closes immediately after opening WITHOUT the need to press CLOSE/OPEN again.
Hi David, i have an easy circuit design in mind, i will try to post it as a new article, and let you know soon…
I have designed the required circuit, you can find it in the following link:
https://www.homemade-circuits.com/automatic-door-controller-circuit-using-a-single-push-button/
Excellent work! Will begin construction. And extra thanks for the prompt response.
Sure, no problem! All the best to you.
Let me know how it goes.