The post explains a simple yet very useful 0 to 50V dual power supply circuit which will enable a full 0 to maximum dual voltage +/- control of the input power supply DC. It also includes a wide range current control feature right from 0 to 10 amps. The idea was requested by Mr. Tamam.
Technical Specifications
It was my long term dream to build a 2 channel power supply for personal use, I have seen a lot of circuits, but those does not fit my criteria.
However, please take a look at the following requirements and let me know if its possible or not, if possible I will be the happiest person in the world.
1. Output voltage range: -50V to 0V to +50V ( must be adjustable by individual channel )
2. Output Current range: 0A to 10A ( must be adjustable by individual channel )
3. Output would be Duel channel, means total 6 outputs,
Channel 1 (Positive, GND, Negative) Channel 2 (Positive, GND, Negative)
4. Power Supply Unit should contains 2 Voltmeters and 2 Ammeters (Analogue) for 2 individual channel.
5. Power Supply Unit must have short circuit protection and cooling fan featured and extreme heat protection.
6. I don't want to use any PIC or AVR, so please avoid those.
Money is not a matter here, I will spend continuously until above requirement meets.
Even If I need any custom transformer I will order and make it from our local area.
I have seen many ready made power supply in market but I want to make it by own hand. You just show me the way... please bro, I will be pleased to you for lifetime.
Thank you very much !!
Best Regards,
Tamam
For calculating the part values accurately, you can refer to this bench power supply article
Circuit Diagram
The Design
The basic design of the proposed 0 to 50V variable dual power supply circuit with 0 to 10 amp variable current facility is shown in the above figure.
The entire design is transistor (BJT) based and is virtually indestructible. Moreover it's equipped with an over load and over current protection features.
The two section included in the design are exactly similar with their configurations, the only difference being the use of PNP devices in the lower configuration while NPN in the upper configuration.
The upper NPN design is configured to produce a variable response right from 0.6V to 50V positive while the lower PNP section becomes responsible of producing an oppositely identical response from -0.6V to -50V output.
The Transformer Specs
The maximum limit could be suitably changed simply by changing the voltage rating of the transformer. However for higher voltages you may have to appropriately upgrade the BJT voltage ratings accordingly.
In both the designs, P2 executes the function of varying the voltage levels as desired by the user, while P1 functions as the current regulator and is used for adjusting or setting the output anywhere from 0 to 10 amp current. Here too the maximum rating depends on the selection of the transformer amp rating and may be changed as per individual preferences.
T1s in the both the sections become the fundamental part or the heart of the entire voltage control functioning in the circuit, which becomes possible due to the popular common collector configuration of the devices.
The other two active BJTs only help to implement the same just by controlling the base power of the T1s thus making it possible to adjust the thresholds to any desired user defined voltage and current levels, as per the ratings of the transformer or the input supply.
You may also like this LM317 based Dual Power Supply Circuit
Parts list
- R1 = 1K, 5 watt wire wound
- R2 = 120 Ohms,
- R3 = 330 Ohms,
- R4 = to be calculated using Ohms law, R = 0.6/Maximum Current Limit, Wattage = 0.6 x Maximum Current Limit
- R5 = 1K5,
- R6 = 5K6,
- R7 = 56 Ohms,
- R8 = 2K2,
- P1,P2 = 2k5 presets
- T1 = 2N6284 + BD139(NPN), 2N6286 + BD140(PNP)
- T2, T3 = BC546 (NPN) BC556B (PNP)
- D1, D2, D3, D4 = 6A4,
- D5 = 1N4007,C1, C2 = 10000uF/100V,
- Tr1 = 0 – 40 Volts, 10 Amp
Using Op Amps and TIP35
Here's another accurate adjustable dual power supply circuit, for your reference:
Using MJ2501 and MJ3001
The versatile dual power circuit featured here can supply a maximum of 50 volts across its two output rails, capable of handling currents of up to 3 amperes.
To support these output levels, the secondary of T1 should have a rating between 4.5 and 5 amperes. Furthermore, it includes comprehensive current limiting protection.
This circuit is well-suited for applications involving audio power amplifier modules that demand supply rails of up to 50 volts. Please take note that R8 should be set at 47 ohms.
NOTE:
Q1 IS MJ2501
Q2, Q104 ARE BC448
Q3 IS BC182
Q4, Q102 ARE BC447
Q101 IS MJ3001
Q103 IS BC212
D1, D2, D101, D102 ARE ANY GENERAL PURPOSE SILICON DIODES
D3, D103 ARE 1N4002
ZD1, ZD101 ARE 5V6 400rnW ZENERS
BR1 IS 600V 10A BRIDGE RECTIFIER
Hello,
I got 50V / 800W toroidal transformer, interested in building adjustable linear power supply ( is it possible 0-50V / 16A ?)
Regards
Hi, Yes it is possible, however at 16 amps the power devices can dissipate a lot of heat.
Hello jonney I have a 28v± power supply .I want to reduce it to 18v± supply .can I use this circuit .if isnt what are the variations of this circuit .thank you very much .
You can do it using the above the circuit. No changes would be required.
Hi, Swagatam. I Want to know the value of the base resistor at T3 since i cannot see it. Thanks.
Hello Johnny, it can be a 1K 1/4 watt resistor. R5 can be eliminated, it is not necessary.
Thankyou so much, my man !!! You truly are one in a million. Now i can proceed with this project. God bless.
You are most welcome Johnny!
Consulta, si cruzo las puntas, la fuente sigue inyectando corriente?
If you short circuit the output, the output will continue to supply current as determined by R4.
Hi sir
I have to increase voltage. From 50v to 60volt. What i have to change in cercuit.
Pleace give a replay
Kind regards
Ashtaman
Hi Ashtaman,
The output voltage depends on the input voltage. if you use around 62V at the input then you will get around 60 V at the output.
Thank you very much sir
You are welcome!
hello, first of all, thank you for this post.
I have a question. please help me. I want to make an adjustable power supply circuit with a voltage between +-20 to +-50 (dual output) with low noise in the output. what do you refer to me?
thanks.
Hi, I can recommend you the circuit which is explained in the above article. However, I am not sure whether it has a low noise output or not.
Hi, Swagatam. I would like to know where to incorporate my ammeter(s) in the above 50v psu.I do have all the components ready to start.
Regards.
Hi Johnny, you can connect the ammeter in series with the positive output lines of the power supply circuit
Wow! You are an amazing man. Its been so long since this was published and you stil reply to questions about it and so quickly at that. Thanks, man. May you be blessed.
No problem!! I am always glad to help!
Hello, I am very happy and thank you very much for this design of the laboratory source, it has all the parameters that I have been looking for for a long time. And I would like to ask if it would still be possible to make signaling using LEDs of constant current and constant voltage? If so, how?
Hi, thanks, and glad you liked the post.
LEDs cannot be used to indicate CC/CV. You will have to use a voltmeter and ammeter to confirm those parameters.
You can also refer to the following article for getting information on a related topic:
How to Design a Bench Power Supply Circuit
Good morning, are P1 and P2 potentiometers to regulate de tension an current needed? If yes, is it ok to use 50k pots?
thank you
P2 are for regulating the output voltage, P1 are for regulating current.
Hi Swagatam sir. first of all, thank you so much for your innovative ideas and sharing your knowledge with us. I really enjoyed your circuit and all those details you have provided. you are the only one who can help me, and ill be grateful if you manage some time for me.
As an electrical engineer, I always wanted a professional lab bench power supply. i have googled many times but none of those circuits fulfill my needs. anyways please take a look at my requirements and if it is possible please teach me or us how can it be done.
1) input :- 70v 11 amp dc ( i have such a transformer 35-0-35 ac )
and I want its output to be regulated.
2) v output :- 1.5 – 70v variable dc voltage.
3) I output :- 0 – 11amp variable current.
4) short circuit protection
please sir you are my only hope.
thank you in advance
Rahul.
Thank you Rahul, I can definitely help you.
You can refer to the following post for understanding how to build a bench power supply with all the required specifications.
You can try the 5th schematic from top:
https://www.homemade-circuits.com/how-to-design-a-stabilized-bench-power-supply-circuit/
However, being a linear power supply the transistor can heat up a lot at lower output voltages. To prevent this you will need a transformer which has tapping after every 12V. So it should have voltage tapping at say 12V, 24V, 36V, 48V, 60V, and 70V. When the output load is below 12V, you can select the 12 transformer input range, and then adjust the power supply precisely to suit the load specifications, and so on. This will keep the transistor a lot cooler.
For high power output you can replace the 2N3055 with two TIP35 in parallel over a common heatsink.
Similarly, you can calculate and fix the current limiting resistors as per your output requirements.
I have enjoyed looking through your power supply designs. I do have a couple of questions. First of all have you ever built a 50VDC 20-25 amp power supply? Certainly it would not difficult to take this design and remove the -50VDC portion. Can I put a second T1 and R4 in the plus side. One version of the ARRL handbook does this on a 28V high current supply except they useTie them together at the collector, the base and the other side of R4? Also, in your designs as well as many designs I see I find it difficult to source an appropriate transformer. Do you have any sources that you can recommend for transformers? Another question is do you have any idea regarding noise that would be seen into RF bands as hinted above the intent is to drive a Ham HF Band Linear Amplifier. My bailout may be to build a Lithium-Ion Battery Pack sufficient for a couple hours of work. Any additional thoughts or ideas would be appreciated. Thanks.
Thank you, and glad you liked the posts.
The positive single supply version of the above design can be seen in the following article:
https://www.homemade-circuits.com/how-to-make-versatile-variable-voltage/
To get 25 amps, you may have to replace the T1 with at least 5nos of TIP142 transistors in parallel and mounted over a common single heatsink.
To ensure the devices don’t heat up too much you may have to use a selectable voltage transformer, which allows you to select different input voltage ranges matching the load voltage specs, such as 6V, 12V, 18V, 24V and so on. So for example if the load is a 7V load, then the 12V transfromer range could be selected and the power supply’s pot may be further used for tweaking the output to 7 V, this will ensure that the devices never get too hot.
To reduce noise you could use large filter capacitors across the circuit input terminals and also at the output terminals.
Sorry, I do not have any information regarding sources where the transformers could be procured.
Perfectly explained thanks a lot MR Swagatam, i used to read the comments first before asking a question, and of course i got it “To get 25 amps, you may have to replace the T1 with at least 5nos of TIP142 transistors in parallel and mounted over a common single heatsink.” Except how about using c5200 and a1943 instead of tip142 they are readily available in my country.
I know you’re always an answer to my technical problems.
On behalf of the electronic hobbyist
May God bless you
Best regards
Poloko
Thank you Poloko, Glad you found the post useful.
Yes 10 of those transistors can work, however since the specified transistors are not Darlington pairs, their response might not be as good as TIP142.
dear sir
i need replace battery 1.2 v 10 a with power supply 220 vac and etc .
can you help me.
really i do not find battery because very expensive .
i wana use power supply for give 1.2v and 10a dc.
Hello Abbas, An SMPS circuit would be needed for getting a 1.2V at 10 amp from 220V, presently I do no have this circuit, and it seems it is also not available anywhere online.
hi I want to make adjustable voltage and adjustable current power supply. Output voltage range is 0 to 10 v
and current range is 0 to 30 amp.
hi, you can try the concept explained in the following article, and modify it according to your required specifications:
How to Design a Bench Power Supply Circuit
Hello dear sir.
thank you for your good projects.
Sir! can I ask you please divide T1 to two part (A and B) and then write those name in schema and update the schema ? please.
THANKS FOR YOU.
Farzad Mohammadi
Iran, Kurdistan, Ravansar.
Thank you Farzad, In T1, the transistors which are on the outer side are the main power transistors 2N6284 NPN and 2N6286 PNP….while the transistors that are on the inner side are the smaller transistors BD139(NPN) and BD140(PNP). I hope you have understood now!
Sir, In the circuit diagram of 0-50v 10A variable dual power supply, the resister value to the base of T3 is not mentioned. May you kindly tell it. I shall be grateful to you. Thanks with regards.
Arvind, you can use a 1K resistor in that position.
you can also go through the following article:
https://www.homemade-circuits.com/how-to-design-a-stabilized-bench-power-supply-circuit/
Thanks so much for making this design available. Unfortunately I have run into some problems. I’m using the BD139/140 and BC546/556 but as output I chose the darlingtons MJE703/MJE803 as I only need 1A. My problem is that when I turn op the voltage, T2 get extremely hot and eventually blows of and burns the R2 resistor. The max. Voltage I can get out before T2 blows of, is approx. 35V although my trafo output is +-35ac. Do you have any idea what’s going on?
Thanks for trying this design, which transistor exactly did you use for T2?….please try BD139, that should be enough to make it work perfectly….by the way if you have used a BC546, with 1 amp 35V as the input, a BC546 for T2 can never blow
Thanks for your reply. I used the BC546 as T2, so its really strange. It has a normal temperature when the output voltage is turned all down, approx. 3V, but when I turn the output voltage up, it gets more and more hot until it short circuits and blows of R2. My input voltage is 35VAC = approx. 50VDC. But I will try with the BD139.
Yes you can use BD139 and see how it works, since BD139 is rated at 80V
Smetrik güç kaynağı devresinin T 3 Transistörünün beysindek direnç numarası yazılmamış açıklarsanız sevinirim.
Resistor at the base of T3 can be 1k.
You can also refer to the following post for an in-depth study of the concept
How to Design a Stabilized Bench Power Supply Circuit
Could this be used for making a dual rail supply with a current rating of 100amp for the negative to ground and positive to ground of a 100amps.
if so how could this be achieved please?
100 amps is too big, not feasible with this concept!
Hi all,
I’ve built Swagatams power supply and want to contribute with this description of my approach. If I point out some issues this does by no means mean me criticizing Swagatam. I have all respect for people publishing something for free and even more when they support their project as thoroughly as Swagatam does. It’s my experience with my setup.
Now, I had a very nice bench power supply that is exactly adjustable down to mV and mA. Problem was, it has only +-15V at 3A, and I had several occasions where I needed more than that, +-30V at 1-2A would be nice. Overcurrent protection was another main requirement. In comes Swagatams design.
As built, it does what is to be expected. I run it with +-42V at 3A. The voltage and current regulation is a bit crude, but that doesn’t matter, as this is the ‘grunt’ unit.
What parts did I use? It may be a well know trick, but I actually gutted an old Denon AV 5.1 receiver. The old ones without HDMI get tossed out, and when you’re lucky you can get one very cheap. Mine was $10, albeit with burnt outputs.
What do you get out of it? A powerful transformer, a heatsink able to handle a lot. And 2, maybe 4 filter capacitors rated for the voltage coming from the transformer. Those are by far the most expensive parts of our project. If you’re lucky you get fans, feet, pots, silicone thermal pads and lot’s of other useful parts out of it.
I designed a PCB with KiCad to match the case I had from another abandoned project. It fitted the mounting perfectly and was very cheaply made by JLCPCB.
It could be done on a protoboard, but I like honing my skills with KiCad.
On the PCB I added a small 12 volt regulated power supply from another secondary winding of the AV transformer, again using sockets, rectifier, caps and regulator taken from the Denon.
I also added a small circuit using a 4013 flipflop, that toggles on and off on a push button press to switch a relay and activating a LED. This is to have a means of disconnecting the load easily.
A fan controller board was mounted in the case to have a temperature controlled fan. Those are available on eBay for cheap and I had several laying around. I used an 8cm PWM fan from an old PC for that. It too gets it’s power from the small 12V supply.
Then I added two volt/amp meters. Again, those panel mount style meters are cheap on eBay. They are not very accurate, but good enough for my needs. They got their supply from the 12 volts, too
Now, I found out that those cheap meters measure positive voltage only. And they get their reference from the amp meter ground. That worked fine for the positive part of the project, but when connecting it in reverse to the negative side, things didn’t work or shorted. The solution was to give the negative meter it’s own 12 volt supply, so that it was decoupled from the rest and could establish it’s own ground. So I threw in a small regulated 12 volt supply from the standby transformer of the Denon built on a proto board. The meter only takes 15mA.
With all that in place, the supply worked, but I had troubles with the current limiting pot P1 of the design. It did nothing. The lone R4 does the job fine, though. After some fruitless tries I gave up on it, removed the pot and implemented a 6 way 2 pole selector to switch 6 different R4s in, giving me 0.1, 0.2, 0.5, 1, 3 and 5 amp current limiting. Notice that my switch has a 5 amp rating, but only 150mA when switching. The load needs to be disabled when changing the current protection setting.
Tests on the positive side proceeded. The rectified voltage without load is 48 volts, 42 with load. Btw, the big manufacturers are not as generous with their cap voltage as Svagatam, saving some pennies there. The filter caps in the Denon had 10000uF at 50V. Close, but works. When I tested the full 42 volts with about 3 amps the magic smoke escaped and the fuse blew.
Investigation revealed that it was R2 that burned. It did it, because the BC546 T3 could not handle the load and shorted. It took T1 (I’m using a TIP142 here) with it, also shorting, causing the fuse to blow.
The issue that T3 is perhaps underrated is mentioned in the comments. So I replaced the parts, upped R2 to 1/2 watt and changed T3 to a BD139. That worked fine and the BD139 can handle the load. I modified the negative side accordingly with a BD140.
The supply works fine now and I’m very happy with it. I also learned a lot, and that is what DIY is all about, right?
Thanks again to Swagatam for the nice project.
Regards
Thank You Rytikar for your detailed analysis and the related suggestions!
Initially your comment was sent to the spam folder due to the external link which you had included in the comment. It is an automated process.
The above power supply is a basic cheap linear power supply concept which is not among the most efficient power supply designs.
The current and voltage handling capacity are directly associated with the power ratings of the various components used in the circuit which will need to be upgraded accordingly.
I may not have calculated the part values very accurately, since I knew it is just about upgrading them appropriately which could be done by the user while experimenting, just as you did, and I appreciate it very much.
The current is not properly regulated by T3, since T3 switching is also linear and sluggish, so the effect is not sharp and unidentifiable quickly.
Instead if an op amp based sensing is incorporated then the current control could be more effective using a pot.
You can even try a MOSFET for T1 and see how it responds, although the highest voltage will be 7 to 8V less than the input supply with a MOSFET.
A big drawback with this supply is the heat dissipation, which could be improved by using a tapped transformer, at 9, 18, 24, 40V, which could be selected depending on the output requirements, and this would hugely help to save power by eliminating large dissipation from the transistors.
Anyway thanks again for your helpful tips, I am sure the users will find them very helpful
Hi all,
two findings to add to the above.
The BD139/BD140 T3 still gets over 100 degrees C warm and needs to be mounted on a heatsink.
I started to use a 1 watt 1K for R1, but that is not enough, it needs to be 5 watts.
Regards