The presented universal power supply circuit can be used just for anything, you can use it as a solar battery charger, bench power supply, mains battery charger circuit, or for any desired application regardless of the voltage and current range, which are extremely flexible and fully adjustable.
Main Features:
The mains features of this power supply is that it is highly flexible, and will allow you to get a variable voltage from 0 to 30 V, and a variable current from 0 to 3 amp. Both the parameters can e controlled through a potentiometer.
The current limit can be upgraded by suitably increasing the rating of VT1, and by adjusting the value of R20.
Using a Single LM324 as the Main Control Device
The design of a simple opamp based power supply is not complex and utilizes ordinary parts such as IC LM324, a few BJTs and other associated passive components, yet it is too flexible and can be calibrated to any desired voltage and current range, right from 0 to 100V, or 0 to 100 amps.
I accidentally found this design from an online website and found it quite interesting, although I already have a similar design published in this site by the name zero drop solar charger circuit, the above shown circuit looks more meticulously designed and therefore is more accurate.
Referring to the above proposed universal power supply circuit diagram, the functional details can be understood with the help of the flowing points:
How the Circuit Functions
The IC LM324 forms the heart of the circuit and becomes responsible for all the involved complex processing.
It's a quad opamp IC meaning it has four opamps in one package, and all the 4 opamps (OP1----OP4) from this IC can be seen effectively employed for their respective functionalities.
The input supply which is derived either from a mains transformer or from a solar panel is suitably stepped down using a shunt zener network VD1 to provide a safe operating voltage for the IC LM324 and also for generating a stabilized reference for OP1 non-inverting input, via R5 and preset R4.
OP1 is basically configured as a comparator, wherein its pin3 is applied with a set reference, and its pin2 is connected with a potential divider across the output of the power supply for detecting the final voltage across the load.
Depending upon the setting of the R4 which can be a pot, the OP1 compares the level of the output voltage delivered by VT1 and trims it down to the specified level. Thus, the pot R4 becomes responsible for determining the effective output voltage and can be adjusted continuously for getting the desired voltage across the indicated output terminals of the circuit.
The above operation takes care of the variable voltage feature of the proposed universal power supply circuit. VT1 and VT2 must be appropriately selected as per the input voltage range for enabling the devices to perform correctly without getting damaged.
The variable current feature of the design is implemented through the remaining three opamps, that is collectively by the opamps OP2, OP3, and OP4.
OP4 is configured as a voltage sensor and amplifier, and it monitors the voltage developed across R20.
The sensed signal is fed to the input of OP2 which compares the level with a reference level set by the pot (or preset) R13.
Depending on the setting of R13, OP2 toggles OP3 continuously such that the output from OP3 switches off the driver stage VT1/VT2 whenever the output current tends to go above the fixed level (set by R13).
Therefore R13 here can be effectively used for setting up the maximum allowable current across the output for the connected load.
The resistor R20 may be appropriately dimensioned for calibrating the maximum allowable current for the load, which can be tweaked by R13 from 0 to maximum.
The above versatile features makes this universal power supply circuit extremely efficient, accurate and fail proof so that it can be used for most electronic application one can think of.
The design can be expected to be fully short circuit and overload protected, provided VT1 and VT2 are appropriately cooled by mounting them over adequate heatsinks.
Hi all! Here is the original of this scheme https://vrtp.ru/index.php?act=categories&CODE=article&article=2349, many people repeated it. КТ818 is very old russians transistor, “datasheet” is here https://www.5v.ru/ds/trnz/kt818.htm. KT825 = TYPE147G, but Darlington’s type is not very suitable for this (the tendency to self-excite increases). It’s best to use a regular high power pnp transistor around 60..80V/10..15A, I used a 2N6491. Someone’s circuit was excited due to poor quality LM324, a capacitor with a capacity of 150-470 pF between pins 1 and 2 solves this problem.
What are your specifications for vT1? KT818/KT837/KT825? I cannot find datasheets for any of those transistors. And while I can imagine a variety of substitutes, I wondered exactly what did you have in mind with those particular devices? i.e. why those, and not others?
This is not my design, so the transistors were not specified by me.
However, the values of the transistors will depend on the output requirement by the load. Meaning it depends on the maximum voltage and current specifications of the load.
If you can provide the maximum specifications of the load, i can help you to figure out the exact transistor equivalents.
Hi Swag,
Can you place the list of components of the above circuit.
I can’t figure out what type of resistors are R7, R8, R3 and other similar.
Best Regards.
Nélio Abreu
Hi Nelio,
I am feeling too lazy to do it, but I may consider updating it sometime sooner.
The resistors which are marked with two slanting parallel lines are 1/4 watt 1% MFR,
The R3 resistor is a 2 watt 1% MFR resistor.
The R20, 0.1 ohm can be a 2 watt wire-wound type resistor.
The rest of the resistors are all 1/4 watt 5% CFR.
🙂 Ok.
Hi,
What P controls voltage and current?
Best Regards.
Nélio
Hi, the 10K pot connected at the pin3 of the opamp controls the output voltage.
Thanks.
Best Regards.
Nélio
Dear Sir, I want to make a 0-60V, 0-40A Variable power supply circuit and vary the same using a 0-5v external analog reference instead of a potentiometer. What changes should I make to the circuit above to achieve the same. Kindly advise.
Hi Ananth,
I think you can try the following circuit, disconnect the (+) input of the op amp and connect it with your 5V supply:
https://www.homemade-circuits.com/wp-content/uploads/2021/03/op-amp-power-supply-compressed.jpg
Yes sir that works but I can only supply a max supply voltage of 30V to a LM324 opamp and hence the output of the opamp will vary from 0- 30V. How do I increase this voltage to vary from 0-60V at the final output of the circuit. Please advise.
If you are referring to the LM324 circuit published in the above article, then I think 60V is possible, because the supply pin of the LM324 is stabilized with TL431 IC
Yes but even the TL431 can only regulate voltages between 2.5 to 36V at most. Is there any other IC which I can use instead. Please advise.
I think you can search for 100 V Opamp, you would be able to find a few good options
Dear Sir, I don’t have PNP Transistors, meanwhile I found some 2N3773 from the junk dealer. So I tried to configure the circuit at : https://drive.google.com/file/d/1ZGBvVr7mWW5TMT8fi2tio5IWyQM5G8GP/view?usp=sharing Can you please examine and suggest necessary corrections ?
Thank you very much for valuable advice.
Dear Imsa, if Q1, Q2 were PNP transistors and you have replaced them with NPN transistor then that might not work. PNP cannot be replaced with NPN transistors.
I am an led manufacturer, based in Pune.
Kindly connect for PCB design/design validation and trouble-shooting work at
Thanks in advance
Sorry I don’t do freelance job.
Can you suggest a simple circuit to achieve variable power charger circuit which can be used to charge different devices from the same charger . like phone and laptop from a single charging brick.
I can use the following components if needed:
IC 7805 , Arduino
Arduino is not required, you can customize the following concept:
https://www.homemade-circuits.com/regulated-car-battery-charger-circuit-for-garage-mechanics/
Hello again, commented on the transistors in parallel. I really like this design. I assume I could use a couple 2n3055s in parallel. The supply that I am going to build will be 0-36v, 0-25a. Could you comment on any other changes to increase the current capability of this circuit.
Thanks again,
Ken
2N3055 is a NPN while the main device above is a PNP, so you may have modify the design considerably for using 2N3055s
You can try one of these designs:
Voltage Regulator Circuits using Transistor and Zener Diode
Hi Swagatam,
According to your instructions, I used both (4905,9540) MOSFET, but the output voltage did not change at first and remained high.
After that, I changed the two resistors (R9,R10) to 200 ohms and the voltage changed a little, but still irregularly and with a slow rhythm from top to bottom.
Thanks in advance for your guidance to tell me what I need to do to be able to have good control over the voltage.
Can I use the DAC on the gate of Mosfet with a feedback from output to have high accuracy in output voltage?
Hi Saed,
A P-MOSFEt should work exactly like a PNP BJT in this circuit according to me. You can connect an LED in series with the op amp output 10k resistor to make sure that the NPN does not conduct due to any leakage voltage. Plese confirm with a power BJT again, If the circuit works with a BJT then it should definitely work with a mOSFET also.
Sorry I can’t figure out how a DAC would help in this situation?
Hi Swagatam,
First i want to thank you for sharing this design I made it last night and it worked great(with Tip36 for t1 and Tip122 for t2).
The need I have for my project is about max 30v and 10 amper for continous using.
I can not use big heatsink for tip36 but I can use 12v fan instead.
I connected a 100-watt 12-volt lamp to the power to test, and within five minutes the temperature of my rectangular heatsink was extremely hot(2cm*3cm*6cm heatsink).
What can I do for reducing the temperature?
Do I have to use another transistor or can I connect the same transistor in parallel in groups of two or three or more so that the temperature rises less?
Hi Saeid, Glad you could make it successfully, yes you can put more transistors in parallel for reducing the heat, or replace the transistor with a P channel MOSFET, such as IRF4905 or IRF9540 etc
I thought we could change the voltage because of the operation of the transistors at their linear point in this power supply. And we do not have this linear state in MOSFETs.Where is my view wrong?
And if MOSFET can be an alternative, which part of the circuit should I change?
Best regards.
The circuit is not actually linear by nature, since it is not being used in the emitter follower mode. Nonetheless, a MOSFET is also a transistor and can be used in the linear mode if required, although here the VT1 is not connected to behave as a linear regulator.
You can change VT1 with a P-channel MOSFET
Dear Sir, In the circuit above, can I use HGTD8P50G1 (500V 8A) or FGA25N120ANTD (1200V 50A NPT Trench IGBT) for VT1 ? if yes, what are the other changes required in the circuit? I like to have 100~120V Output to charge 12V 40Amp batteries in series.
Thank you very much for your valuable advice.
Imsa Naga
Dear Imsa, according to me no changes will be required except the VT1, which you can replace with your own power device.
It seems R3 will also need to be changed with a 10k 5 watt resistor
Dear Sir, thank you very much for the express response… I’ll first try the circuit with the FGA25N120ANTD and get back to you for further advice.
Thank you once again
No problem Imsa, please go ahead!
Sir,
Can you please help me with a schematic for regulating DC voltage from 0 to 100V, and Current from 0 to 100 amp. Fixed Voltage Source of 100V and 100Ampere is available.
Akash, using a linear regulator for 0 to 100 V can make the transistors very hot at lower voltage adjustments, so it is not recommended,, and SMPS can be extremely complex, so i have no idea about it at this moment.
Sir,
1. Limiting the circuit to 30V regulation, can we increase the output current rating to 0-20A ?. If possible what changes may be required ?
2. The transistor KT818/837/825 all are seemed to be obsolete. Can you please recommend an alternate part number which can purchased from Digikey/Mouser.
Akash, to get 20 amp at the output, the input must be rated at above 20 amp.
You can replace the transistors with TIP36 for VT1 and TIP122 for VT2
Good day sir
May I ask what are the input signal requirements of this circuit?
redriot, you can use a 35V DC 5 amp at the input
Yes, that is correct Sir, but what i do not understand is that the sens resistor is in series with my load through the output and my output volts = 60 and output amps = 100 and that means 6000 watt. How is it possible for the sense resistor to withstand that current being rated at only 20 watt.I have mentioned to you before that i do not know how to design circuits, can only build them. Now if i look at this circuit, i see my negative output gets connected to R 21 for sensing, i think, and through sense resistor to ground.Negative output also connected to BC 847 emitter (ground),VT 2 emitter (ground), OP-AMP PIN 11 (ground), R 6 (ground), VD 1 A (ground), R 13 (ground) and C 4 negative (ground), So to me it looks like my sense resistor is in series with my output. Now Sir, please correct me if i am wrong, C 4 negative is the MAIN GROUND and that is why my sense resistor will not burn at above mentioned output levels. C 4 is a smoothing capacitor and for my output specs, what micro farad do you suggest C 4 Sir. I have read somewhere that a 1000 micro farad per amp is adequate? (i know the cap volts must be much higher than input volts, 100 to 140 volt.) Is that correct Sir and if C 4 is the main ground, that track will need to be off the PCB to be able to carry the current and of course all the other grounds must also be connected to C 4 ground ? For my output specs, what value and watts must R 3 be and what watts must all the other resistors be. Is VT 1, VT 2 and the sense resistor the only components that need to change for my output specs?
I am so sorry to bother you with all these dumb questions, but by asking dumb questions, so that i do not make stupid mistakes Sir.
Thank you very much for your patience Sir.
Hi Ian, as you can see your 100 amp value has been considered in the formula, and still we get 20 watt as the result. That means the resistor is capable of handling this current. The wire inside the resistor will be thick enough to handle this current. The 20 watt actually signifies the heat dissipation capacity of the resistor here, not the current handling capacity. At 20 watts the resistor will become hot but still will be safe enough not to melt or fuse due to the generated heat.
I hope this explanation might have solved your doubts regarding how a 20 watt current limiting resistor would handle 100 amp current in the power supply circuit.
For calculating the filter capacitor you can refer to the following article:
https://www.homemade-circuits.com/calculating-filter-capacitor-for/
Thank you Sir. And the resistor values and watts that i asked for? And other component replacements, if necessary, that i have asked for in previous question? You gave me the transistor specs via e-mail for my output levels, but surely some of the other component values need to be upgraded for my output specs?
I will run this power supply at maximum output for maximum 5 hours per day Mr Swagatam. I will use massive heat sinks and overkill cooling fans. All the power transistors and large current lines will be off the control board and i will use solid copper bus bars for those lines. If there is a small percentage of noise (ripple) in the output, it is okay for my purpose. I repair old dc welding machines and that is where i get most of my high power components from, like rectifiers, caps, cooling fans, transformers and power transistors. This power supply i want to use for anodizing aluminium parts that i fabricate for my own projects.
Thank you Mr Swagatam.
Hi Ian, all resistors are 1/4 watt 1%, except the collector resistor of VT2 which can be 1 watt 5% each. R20 will be 20 watts wirewound type.
Rest all can be as is.
I wish you all the best for the project.
Haven’t you run into stability issues with this circuit? I do not see any frequency compensation.
It is a linear power supply, not an SMPS
This circuit uses a PNP pass transistor, the configuration is similar to a low drop out linear regulator which are by nature difficult to stabilize as the poles can shift depending upon input conditions and load, there is a high chance this circuit can oscillate or give a lot of ringing on the output. This seems to be one of the reason why most commercial linear power supplies use an NPN pass transistor as that design is inherently more stable, I have been trying to tame a similar circuit lately but it so far has been hopeless really.
Thanks for pointing out the issue. Did you you try theory explained in the following post? I think if the LDO feature is removed by modifying the PNP pass transistor into a PNP/NPN Darlington might solve the issue, as explained in this article:
https://www.analog.com/en/analog-dialogue/articles/low-dropout-regulators.html
Sir,
The resistor I used is 100ohm 30w wire wound. Coming from the voice resistor. And i 100uf 100v cap But he is also getting hot on running bulb or dc motor. When I rotate ampere nob 25% then the bulb is turned on.
Guarav, if your input is 60V then a 100V capacitor can never burn, that’s impossible.
Which resistor are you referring to?? Wheres have you put this resisor
Sir,
I have applied 103ohm 30w * 4nos resistor (R9-10) on the base of VT1 mje2955t * 4nos. All are connected separately.
Sir I checked the whole circuit. The voltage control is working fine. But not current control Circuit is the same as your circuit. TIP122, Bc547 also checked. Current control after turn 25% Current becomes full.
The current range is related to the R20 resistor…you will have different ranges for different R20 values…try smaller values for R20 and check.
Sir,
R20 = v / i (v op4 pin4 voltage)
R=0.3/30=0.01ohm The resistor I used is 0.1ohm 10w. (0.22ohm 5w * 2nos parallel) Now I’ll have to use 0.01ohm 10watt.
yes that’s approximately correct!
Sir,
R20. 0.01ohm 10watt is not in Market. But I used 0.03ohm. Still in Circuit ampere Control is not working. Ampere’s work up-down it’s Zigzag.
Gaurav, How are you checking the ampere? It will be difficult for me to troubleshoot your problems without checking it practically, that’s why I had provided a simpler design earlier.
Sir,
Second Design will get 10amps. What kind of I can find 5A, 10A, 15A. what will be formula for it?
Which second design, do you mean using transistor instead of op amp?
No Sir
Can i get 5, 10, 15Amps manually in this design. https://www.homemade-circuits.com/wp-content/uploads/2019/07/power-supply.png
I too was referring to this diagram. Yes you can get any desired current limit by changing the 0.03 resistor value
Sir,
The circuit is working. Volt – Ampere is controlling. (I’m using the digital ampere meter.) But the C3 Capacitor (100V 100uf) is getting hot. It is not understood.
Is it due to the bulb (bulb12v 35watt)?
Great to know it’s working now!….For the capacitor you can try 10uF/400V, this can absolutely have no chance of burning.
400v 10uf is getting hot enough to fast.
Make a non-polar capacitor by connecting two 100V capacitors in series, connect positive with positive together…then connect the negative ends in the circuit.
Still getting hot.
Then sorry, I do not have any solution for this impossible looking problem….you can ask in Stackexchange electronics forum.
Sir,
Which transistors would (VT1 and VT2) to be used for 60V 20 amps?
What will be the value of R20?
Is this circuit completely short-circuit protected?
Sir,
Op1-Op4 pin no. not clearly shown in picture.
I have updated the LM324 IC pinout diagram, you can use any opamp anywhere by referring to the LM324 pin layout.
Gaurav,
You can use TIP36 VT1, and MJE340 for VT2.
You can use 0.1 ohm for R20 and adjust the OP2 preset accordingly for adjusting the current.
Yes it is 100% short circuit protected according to my understanding
Sir
Can i use TS431 to the place of TL431
Yes you can replace with it.
Sir
R3 2k2 1.5watt not available in market. can i use 2watt or 1watt.
R20 0.1 ohm. Which watt i can use
Gaurav, 2 watt will do, for R20 you can use 1 watt for 3 amp current.
Thank you sir,
Completed my circuit but output voltage adjust not more than 5v. I am using 60v 20amp power supply
Hi Gaurav, did you adjust R4 10K preset to set the maximum output voltage?
What voltage are you getting at the (-) pin2 input of OP1
Op1 (-) pin2 getting 5v
It will actually depend on pin3 voltage, if pin3 voltage exceeds pin2 voltage then the output will be controlled at pin3 level.
Please check pin3 voltage! output will be equal to pin3 voltage.
Also please check LM324 pin4/11 voltage. Adjust it to 24V by setting R1/R2 appropriately, this will allow a range of 24V max.
Sir
I checked LM324 pin4/11 there is getting 10.8v.
Op1 pin2 getting 5v, pin3 = 5.5v.
R1/R2 connected with ts431 ref. There is getting 2v.
I am using TS431 to the place of TL431.
Gaurav, if pin3 is 5.5V then the output will be also around 5V. This circuit needs to be calibrated properly as per user specifications. The 10K preset maximum range at pin3 must be at least 24V…and the pin4/11 must also have 24V for this range to work.
First make sure the supply pins of the IC gets 24V, for this you will have to tweak the R1/R2 network. Once the supply is set at 24V, then you can increase the value of the 4k7 near the 10K preset to 22K for having the full range of 24V at pin3…this will allow you to get an adjustable 24V at the output also
Sir
Input voltage pass through R3 2.2k there is getting 10.8volt. So ic input supply voltage (pin4/11)how will get more than 10.8v
The Pin2 is connected to R8, decrease R8 10K value to 4k7 and check the output response
Sorry, that won’t help, the pin3 range has to be increased, therefore pin4/11 supply has to be increased. Did you try adjusting R1/R2, as I advised earlier?
Please refer to this article for more info:
https://www.homemade-circuits.com/explaining-programmable-shunt-regulator/
Sir
I use r2=47k & r1=5.6k so I get 23.5v. Is it sufficient?
yes that’s OK for the moment, now adjust pin#3 10K preset to get higher voltage at pin#3, this will also increase the output voltage accordingly.
Sir
0.1ohm 7watt / 10watt not available in market..
Can I use 0.22ohm 5watt *2 in parallel.?
yes, you can use two in parallel, by the way did you solve the output voltage problem?
Sir
The Work going on.. So finally i will tell you..
Thanks Gaurav, let me know when it’s done!
When I am connect r2=47k & r1=5.6k. gets 22-23v on pin 4/11. But pin 3 voltage increased 5v to 13v. I am also increase the value of the 4k7 near the 10K preset to 22K Than pin 3 voltage decrease to 8v.
You can remove the 4k7 entirely, and use only 10K preset, this will allow you set the full 23V on pin3
Sir
I made a big mistake to make Circuit Diagram. Tip36c galat set kar diya tha jo thik kar diya hu. Circuit thik se work kar raha tha.
Lekin jaise hi maine 12v motor run kiya to tip36c jal gaya.
Gaurav, when you operate a motor you must connect a diode across the motor otherwise the back EMF will burn the driver transistor….you can also have a diode connected across the TIP36….cathode to emitter, anode to collector. use 1N4007 initially.
OK sir thanks
Sir
I connected the new transistor tip36 to the circuit. And also connected 1n4007 cathode to emmiter and anode to coll. And then i am operate the motor. But again tip36c burned. How can i fix it?
Hello Guarav, did you check the output using some other load, like a DC bulb? Please attach some non-inductive load and first check whether the basic operation of the power supply is OK or not. And I hope you have checked the output with a meter and its variable working?
By the way TIP36 is rated at 25 amps 100V, so it is very unlikely this transistor will blow with a motor current?
Sir
I checked with multimeter that’s ok or variable. I did not use bulb. First time used with motor.
I had connected diode 1n4007 across the tip36c. but not connected to across the motor. That’s the reason for transistor burn’s?
Hello Gaurav, the diode can be connected across the motor or the transistor C/E, both will ensure 100% safety to the transistor, unless there’s some other issue.
It would be better to confirm the working with a bulb, may be a 12V automobile bulb, to verify the perfect working of the circuit on load.
Once this is confirmed then we can diagnose why the motor is causing the issue. You can also try some other transistor like TIP2955 etc. instead of TIP36 to check if the problem is with the transistor.
Sir
I have already mje2955t 2nos. So can i am connecting 2nos of mje2955t in parallel over a single heatsink. Because i am using 50v 20amps PS. (Mje2955t – 10amp)
Hello Gaurav, you can use two transistors in parallel on the same heatsink, but you may have to reduce the base 1K+1K to some lower value.
Sir
Please share your email where i can send my diagram.
Diagram is supposed to be the same as above…I give more preference to comments and reply faster through comments.
Sir
Transistor in parallel circuit.
E/C will be same connect.
Whether to add Resistors separately along with the transistor base?
Gaurav, connect E and C together, but connect separate resistors to bases.
the resistor can be calculated using the following formula:
R = (V – 0.7)hFE / Output Current
V is the input base voltage, hFE can be taken as 25, output current is 10 amps.
Therefore R = 150 Ohms
watts will be 20 watt each
Sir
Whether the resistor will be used in approximately 500ohm * 2nos.
Sir
With the TEP36C’s base I used 1K + 1K 1/4 Watt Resistor.
But now the Transistor MJE2955T 2nos is then it will have to use 150ohm 20watt for it.
But sir I have to use 100ohm 10watt 2nos in series separately in base. Actually 150ohm 20w not available in market.
Gaurav, 1k+1k will not allow 20 amps…but for testing purpose you can try 470 ohms + 470 ohm for each transistor bases, later on you can decrease the values accordingly
Sir
470ohm +470ohm for each transistor bases. And What will the watt for 470ohm resistor.
yes 1 for each, you can try with 1/4 watt initially and check the response.
Sir
I added MJE2955T * 2NOS and 330OHM 1/4WATT on the bases. (470ohm were not available in market) . Circuit check on Multimeter was running fine. Then used automobile bulb. When I turn ampere nob. Transistor burned
Gaurav, turning the current knob R13 can never burn the VT1 transistor. Because turning the OP2 preset R13 can do two things, it will either switch OFF VT3, which will allow the VT2 and VT1 to work normally…or it will switch ON VT3. If VT3 is switched ON, VT2 will be switched OFF, and this also switch OFF VT1.
So in any circumstances the VT1 (2955) cannot burn when OP2 preset R13 is turned.
There’s certainly some other issue with your circuit.
It seems your input voltage is too high. Please check it properly, and make sure it’s not above the maximum transistor rating
Sir
This is an smps power supply. I checked the voltage of PS but could not do the current. Because my amp meter has gone bad. But I already remember that PS 48v is 20amp. Voltage conform shows 51V. PS used to charge 12v 150ah * 4nos battery in series.
Then please give me your suggestion. What i do?
Gaurav, Convert your circuit to this:
https://www.homemade-circuits.com/wp-content/uploads/2019/07/power-supply.png
Sir
I think it’s getting 40amps here. So what do I have to change?
If I use in tip36c * 2nos parallel. So what value would be used in place of 1k + 1k.
What will be the value of R20?
And what else would have to change?
Please suggest Resistor value and watt.
Gaurav, please use the following formula to calculate the base resistor for one TIP36.
R = (supply input – 1)x 10 divided by 20
If now anything goes wrong I’ll not be able to help, because it is not possible without a practical check.
use 10 watt for each resistor…
Sir
I have to complete that circuit.
The circuit you have said does not contain current control. And both the voltage and current are essential.
I recommended this circuit to make your work easy. Current control can be added at the base of the BC547 transistor afterwards.
Sir
I am confirmed smps is 52v 30amps. Now you tell me which transistor to use (tip36c or mje2955t) and what will be the value and watt of the Resistors. what else would have to change?
Hello Gaurav, I have provided the formula for TIP36 base resistor, please calculate it using that formula.
Sir
I want to use mje2955t because tip36c is very expensive.
mje2955t * 4nos.
Resistor for bases
R=(volt. Input-1) hfe/output current
R = (52-0.7) 20/10 = 102. 6
R = 120ohm * 2nos parallel for one mje2955t Each resistors will be 1/4 Watt.
Is this calculation okay?
R20=v/i
0.3/30=0.01ohm.
I’m confused about R20 value and watt. Please you suggest me.
Yes 102 ohms is correct, and will go separately at each base of 2955. don’t connect in parallel
wattage will be
W = VxV / R
= 50 x 50 / 102
= 24 watts
Sir
I have already connected to 0.22ohm 5 watt *2nos in parallel. Is this value / watt correct for R20?
It looks OK to me!
Sir
Can i use 38IH130 igbt. in this circuit.
What would have to change?
I don’t know much about IGBT practically so I can’t suggest on this. Instead you can use power transistor in Darlington mode
Sir
I can use Mje2955t *4nos. And I am using 102ohm 40watt in the base of the transistor. Which I am getting in the market. Will this calculation be right?
Finally tell me your suggestion in this.
Gaurav,
I have already provided you the calculation for each transistor, and that’s correct. But 4 transistors is too much load for VT2, change it to TIP122
Sir
I’m using Mje340 for VT2. Will it change? MJE2955T * 4nos and Resistance 103ohm 40watt * 4nos and 10k R11 * 4nos are used. Circuit is working fine when checking from multimeter.
Input 52v is 30amps.
Will the circuit work fine on bulb or dc motor?
Is my calculation okay?
Guarav,
I am not sure whether MJE340 will be able to take the load, you will have to check it practically. Rest everything looks OK…this time connect a diode across the motor wires…use 1N5408
Sir
I used TIP122 for VT2. I have connected a diode across the motor wires. Circuit properly working and the bulb is also running. Ampere and voltage can controlled properly.
Mje2955t is getting heat, is it normal?
I think everything is fine.
Gaurav,
I am glad it is working fine now. Yes the transistors will become very hot, especially if the input output difference is high. The heat will reduce as this difference is reduced.
Sir Thanks for your support.
You are welcome!
Sir,
There is little problem in my circuit When I’m using an automobile bulb After running few time , the C3 Capacitor got boom. (I used the capacitor C3 45uf 63v).
Which capacitor i can use?
There is a lot of noise in the circuit. Can it be reduced?
Hi Gaurav,
use a 47uF/100V and check again, or 100uF/100V will be also great..
Not sure how the noise may be coming, because everything is solid state in the circuit? Can you check which part is causing the noise?
Sir,
The resistor I used is 100ohm 30w wire wound. Coming from the voice resistor. And i 100uf 100v cap But he is also getting hot on running bulb or dc motor. When I ampere nob 25% rotate. Then the bulb is turned on.
Gaurav,
Sorry it will difficult to troubleshoot, because I don’t know what exactly you may have done in your circuit, very difficult to judge from here.
You can try disconnecting VT3 from VT2 and check again
Sir,
I disconnect VT2 from VT3 Voltage works fine. But get the current full 30amps. And then on connecting VT3. The capacitor seems to be hot. (After adding the bulb).
I think the problem is due to TIP122.
Can anyone else be used instead of TIP122?
Gaurav, I don’t think it’s because of TIP122, still you can try TIP31 instead
Good day sir,
Sorry for an off-topic but i was wondering if you have a schematic diagram with a high frequency power amplifier with semiconductors. This amplifier should work from 100khz to about 7-10MHz and the power should be at least 20W. I would like such a device to have mosfets. Maybe you have such a schematic for i much require this type of device. I was thinking that an intelligent man like yourself must have all kinds of diagrams so again please forgive my off-topic. Where i live i know no engineer…
Thank you,
Thank you Yoshiaki, I have one simple amplifier design, which probably you can try:
https://www.homemade-circuits.com/how-to-make-simplest-100-watt-mosfet/
However to work with such high frequencies you may have to replace all the transistors with equivalents rated to work with max 10MHz, and you may also have to make it using SMDs
Good day sir,
Thank you very much for your reply, i just finished reading it. I will build the power supply, but i have a question: what components do i have to change to make the circuit give 50V at 10A? I don’t know electronics with semiconductors but i like to follow schematics to build things. You said that by changing the resistance of R20 you calibrate the current that goes to the load. On the schematic diagram says that with the present values of the components, the PS will give 0-30V/0-3A. I wonder what do i have to change to make the PS give 100A at 100V.
Thank you,
Thanks Yoshiaki, for getting personalized specifications you only have to change the VT1/VT2 ratings, that’s all. For your requirement any transistor rated at 15amp, and 100V for VT1 will do the job, VT2 can be a 2N2222 BJT.
For the current calculation, you can apply Ohms law as given below:
R = V/I = 0.3 / 10 = 0.03 ohms for 10 amps maximum.
0.3 is the minimum voltage that may be needed to develop across R20 at the desired maximum output current load, to trigger the opamps into action
Thank you sir for your kindness 🙂
_/|\_ Namo Amida Butsu!
You are most welcome Yoshiaki!
Olá Swagatam;
Sou hobista e nao consigo ler direito os valores dos componentes.
Poderia por favor enviar o desenho mais claro para meu imail.
joaobatista.marcelo@gmail.com
Meus agradecimentos antecipados e muito sucesso com seus novos projetos.
Olá João, atualizei o diagrama com números de peça claros, confira!
MUITO OBRIGADO ficou otimo.
Dear sir,
For VT1 shall i use TIP147.
Explain What happen when o/p short circuit ?
For eg o/p 1v short circuit happen this circuit will protect or not sir..
Pls sir i tried many variable circuits all working good but o/p short circuit protection works when above 5v..below 5v it not protecting the transistor became over heat.
Dear Kesav, TIP147 is a Darlingtn so it may not be recommended here, instead you can try a TIP36 for VT1
The short circuit cut off will only trigger when the specified max current level is crossed. In the above design this is determined by the resistor R20.
If you want to achieve total cut off, you can use a relay based cut-off circuit which will totally shut down the circuit and stay latched, This will also ensure no heating up of the devices.
Ola Swagatam,
sou apenas um aprendiz de eletronica e o seu topico me chamou muito a atenção, porem surgiu uma duvida:no começo da descrição voce diz que pode ir de 0 a 100v e 0 a 100A, quais mudanças devo fazer para atingir tal proporção.
Se puder me ajudar ficarei muito agradecido.
Olá joao, você pode fazê-lo substituindo o VT1 por um IGBT de 150 amp ou conectando 4nos do TIP36 em paralelo sobre um único dissipador de calor comum, isso será necessário … Espero que tenha entendido o conceito 🙂
Hello joao, you can do it by replacing VT1 with a 150 amp IGBT or by connecting 4nos of TIP36 in parallel over a single common heatsink, that’s all will be required…I hope you understood the concept 🙂
Agradeço muito pela atenção farei as mudancas
O prazer é meu!!
Hi Swagatam,
After long I finally got the time to make this power supply. I tried to draw the schematic in NI Multisim, when I try to simulate it, it does not work. Also the voltage does not change at the output.
I have incorporated all the changes suggested by you in my previous posts.
I also noticed that in NI mulstisim, there are lot of variants of LM324. I dont know which to use. For my schematic, I used LM324AD.
I can email you the schematic file or upload it somewhere, would it be possible for you to check what is going wrong? I really need this power supply pretty bad.
Hope you can help me on this.
Thanks.
Hi VM, Making the circuit on simulator will not help, it won't allow you to assess the design correctly, because a simulator results can be misleading and confusing…it's better to make it practically on a breadboard or veroboard and then tweak the results as per the required specs.
I have always trusted my brain simulation more than simulators and has always paid off
Hi Swagatam,
You make my day with this project, thank you.
Few questions, please:
1. Did you build/test this circuit?
2. If yes, could you measure the ripple voltage when the power source is fully loaded?
3. What values should be expected for this ripple voltage?
Thank you again,
Dan.
Thanks Dan! No I haven't tested it yet, but I have studied the design thoroughly and it looks OK to me.
Hello Sir. What modifications should I make if I have a 30V transformer 3A, and want a 0-24V 0-2A output? Thank you so much.
Sir can a TIP36C replace a 2N3055 ?
WHAT WILL BE THE MAXIMUM CURRENT THAT CAN BE TAKEN FROM TIP36c ?
RT, TIP36 is PNP and 2N3055 is NPN, you can try 2N2955 instead
TIP36 can provide 25 amps….2N2955 only upto 15 amps
I am designing an universal 0 to 30 V bench power supply with a 300 W transformer. Sir please say whether the following things are possible
(1). There would be separate output terminals other than the variable voltage ( 0 to 30 V ) such as fixed 12 V , 9 V and two 5 Vs but with current control features
(2). The above circuit is implemented to get the variable current and voltage feature.. but can i get maximum of 25 A with this configuration ?
(3). An LM317 in place of 7812 in the circuit given in the following link and output voltage adjusted to fixed 12V . Can it be used as a separate 12V source as said in Question (1) ?
3.bp.blogspot.com/-XgFFR9YXaLg/UbqwRRnhn7I/AAAAAAAAEV4/VpQhXEXk8Rg/s1600/tip36+high+current+circuit.png
(4). If the case that said above is possibe is it ok in taking direct output from that fixed 12V source to 7809 and 7805 to get 9V and 5V sources ?
For reference i am sending one picture of my design to your email ( hitman2008 ).. plz check it out
RT, yes all those features can be easily implemented, but the current selection will need to be done through a rotary switch which can configured to select different calculated resistor values for the 1 ohm/5 watt resistor as shown in the linked circuit
sir why some resistors like R6 R7 in this diagram is represented by two curved lines drawn inside them ?
Does it state that those are high watt ones ?
those are supposed to be 1% MFR types but it is not strictly required
how can i change the voltage and current in this circuit ? which potentiometers allow these ?
i have explained it in the article
Hi Swagatam,
Regarding your last response for using a 1 watt zener diode 3 – 6 volts instead of VD1 (TL431), in the circuit for using input voltage of 50 to 60 volt dc from the trafo, could you please clear the following doubt?
a) TL431 has 3 terminals (K, A, Ref), one of which is used for reference.
b) A zener diode will have only 2 terminals. How and where should I connect this?
Should I simply replace TL431 with the zener and not use the reference point? or is there any other way in which I should connect?
Thanks for your help bro.
Hi VM,
yes, simply replace TL431 with the zener and do not use the reference point
you can remove R1, R2, now they won't be needed, and connect the zener exactly where the anode/cathode of the TL are shown connected.
SIR what is TL41A in the circuit ?
KT815 , KT816 can these be replaced by any power transistors such as TIP32C, 2N5904 etc . ? if the replacement is possible what about the current output ?
TL431 is an IC and a form of enhanced zener diode
the transistors can be replaced with other types having higher V, I specs.
Current can be increased by suitably changing R20 value.
Hi Swagatam !
Referring to my previous questions on this circuit, I checked the data sheet of VD1 (TL431A). The max cathode (Vka) voltage for TL431A is 37 volts dc.
My trafo is rated for 50 volts dc after rectification.
Should I change VD1 to any other type? or would this work fine as it is?
Please suggest if I need to make any changes to the complete VD1 network to make it compatible to 50Vdc of my trafo.
For calculating the wattage of R20, is there someway to calculate the reference voltage at (-) pin of OP4?
Just going by the simple calculation of max output of 50 volts and 40 amps, the resistance value comes out to be (R= V/I)= 1.25 ohms.
Using the power calculation formula P= I^2 x R = 1600 * 1.25 = 2000 watts.
This seems a little impractical at first sight.
I guess I am doing something wrong in this calculation and as you have mentioned, I have to take the reference voltage at (-) pin of OP4 so I guess the reference voltage might not be the full output 50 volts. Can you help on this please?
Thanks for your help!
Hi VM,
VD1 can be simply replaced with a 1 watt zener diode with a voltage rating of anywhere between 3 and 6V.
your calculation regarding R20 might not be correct because here it's referenced with the opamp input and not directly with the load.
the easiest way to identify the right value would be to connect an LED in series with the emitter of the VT3, when this begins illuminating you can be sure that the current control function is working for that particular resistor value… and then go on changing this resistor value until you find the one which illuminates the LED at around 40 amps.
but make sure to connect a 4.7V zener diode in series with the VT2 emitter to compensate the LED drop.
respected Sir, what are the changes required to make it 0-30v 0-5a variable power supply, also could you please elobrate a bit about digital panel meters etc. thanks
Gowhar, you can simply use an LM338 based circuit for your requirement.
please specify what exactly you would want to know regarding panel meters…I'll try to help.
Hi Swagatam!
Thanks for the quick reply.
Are all the resistors in the circuit regular 1/4 watt resistors?
In the schematic,resistors R1, R2, R5, R6, R7, R10 have symbols with 2 cross lines on them. Does this mean anything? I tried searching the internet, but couldn't find any info on this.
Also R3 has a single straight line in the resistor symbol?
If different wattages are required for any of the resistors in the circuit, could you please specify? (Considering max voltage to be 50 volts DC and max amps 40 amps).
My Trafo output is 50 volts DC rectified. Would the VD1 stage in the schematic work fine as it is?
Thanks for your patience, and please bear with my questions as I am still a novice at electronics.
Appreciate your time.
Hi Vimal, you can calculate the wattage by using Ohm's law as shown below:
I = V/R
and followed by this
P = I^2 x R
so at 50V for example the R3 2k2 wattage would be
I = 50/2200 = 0.022amps
therefore P = (0.022)^2 x 2200 = 1.06 watts or 1.5 watt (safer value)
except R3 all can be 1/4 watt rated according to me….I am too not sure about those lines, may be those were specified in the actual article…however you can use 1/4 watt 1% MFR resistor for extreme safety and should be more than enough
use 1% MFR 1/4 watt resistors for all except R3, and R20
if VT1 transistor is rated at over 60V then there would be no problems
Hi Swagatam,
I have been really looking for something like this since long. Thanks for the post.
I have a few questions.
1) I already have a transformer with 50 volts DC output capable of 40 amps max.
Can I use this transformer as input (50 vdc) for this circuit? What changes should I make to VD1 so that I can use 50 vdc as input?
2) How do I calculate the value of R20 to make it suitable for the max 40 amps the transformer is capable of? Also what should the wattage be of R20?
3) What changes do I need to make to VT1, VT2, VT3 to make this circuit capable of 40 amps?
Please do suggest any other changes which you may feel fit for making this circuit.
Thanks for all your help.
Vimal
Hi Vimal, thanks
1) with a 50v transformer, the rectified output could be well over 56V
no issue though, ….you can use TIP36C for the power transistor VT1, for VT2 you can use MJE340, and VT3 can be a BC547
R20 can be calculated as follows:
R2 = V/40 where V is the reference voltage at the (-) pin of OP4
…sorry TIP36 is rated at just 25 amps.
instead you can try 2N5684 for VT1
I see a problem here. Under high current R20 will cause a voltage drop on load. This is no good, current sensing better to be done before regulator so this drop is compensated.
R20 is specifically for sensing and restricting high current above a certain range as selected by the user…R20 can be modified anytime for increasing the current output, as desired
no matter where R20 is introduced it will still drop the voltage across the load…
Sir good day to you
Please suggest me How to choose mov voltage Does have any formula?
How to select Max continuous voltage or Max clamping voltage ?
Rajkumar, MOVs are determined by their clamping voltage spec, suppose if you select a 400V MOV then it can be expected to activate and protect whenever the voltage spikes occur at around 400V….
…only the clamping voltage is normally considered for MOVs…
Sir swagatam,l'm previleged to be regualar follower to have been taping ur ideas and knowledge from you blog.i think you will find time to clearify me on the these issues,in home made circuit they were two circuits about alternator power booster,one from you another one hobbyist.the one from you, can i use same type of capacitors the guy used for your circuit?or did he used polarise capacitor for his circuit?thirdly can your own circuit carry electric pressing iron or boiler with small generator of 650va etc Thanks for your reply
ndukwe, you will need to use only non-polar capacitors for the design specified by me, and those must be rated at above 400V minimum….the value of the capacitors will determine how much load it can sustain with the boosted voltage. electrolytic capacitor will blow of immediately, so never use electrolytic polarized ones.
yes it will be able to handle iron and boiler provided the capacitors are of high value….you can use fan capacitors for the application.
ok swagatam,
thank you.
i follow your blog!
regards erchiu
Hello Swagatam,
Thank you for this post. I intend to build a lead acid battery charger for a 12V 1.3Ah battery, using a solar panel (planning to use a 12V 5W one). I am relatively new to electronics and hence seek your help to understand and bring up the required circuit.
Can I use the circuit in this post for this purpose? I intend to keep the battery always connected to this charger circuit and drive a few LEDS as load by the battery. The intention being that the battery is continuously charged during day time.
If this circuit can be used for the charger – are there any concerns if the input voltage drops low and cannot charge the battery (for e.g. at night, when the output from the solar panel will drop significantly); should I add any additional control circuit to detect low input voltage and detach the charger from the battery? Also in such conditions when VT1 is not conducting(?) when the battery is fully charged, will the battery discharge through R6 and R7?
Thank you!
Hello NPI, the above design is too elaborate for your application, so it may not be appropriate.
You can use the first circuit that's shown in the following article:
sorry here's the link:
https://www.homemade-circuits.com/2013/03/simple-dc-ups-circuit-for-modemrouter.html
just replace the adapter input with your solar panel input.
Thank you, Swagatam.
I will check this out. What should be the value of R1 (after the TIP122) to use for my battery (for a 1.3Ah, I guess the charging current should be around 100-130mA)?
it is not too critical actually, you can use any resistor which allows around 100mA to 200mA current to the battery…you can confirm it with some trial and error.
hi swagatam, i am using a android tablet for to visit your website, but i not succeed to see good the diagram. can you tell me as i can do? thank you so much.
regards erchiu
hi franco, in my android mobile all the diagrams are distinctly clear….not sure what might be causing it in your tablet.
Is this design itself an inverter? What KVA? does require a transformer?
Is this design itself an inverter? What Kind and does require a transformer?
It's an AC to DC variable power supply circuit, the DC needs to be supplied from a suitably rated transformer
sincer esti o comoara de om.mereu ne uimesti cu postarile tale.esti un om deosebit.
gogotu, can you please translate the language in English??