Hello everyone: This circuit is quite good but the power transformer should not exceed 20V. The DC voltage in the supply (+ Vdc, -Vdc) in the operational ones when setting the 24V voltage exceeds the maximum values for which the manufacturer designed it. The maximum data sheet voltage says + Vcc - (- Vcc) = 36V, recommended 30V. It may work well for a while and then the operational ones will burn.
Do you use 24V DC or 24V AC? It says that need 24V AC, but it's a little dificult get a 230V AC/24V AC transformer, it had to be toroidal. In the PCB it alredy have the 4 diodes to convert to DC, are any problem connect the 24V DC instead AC?
+Francisco Madeira you must use AC voltage for the circuit to work. There is a negative voltage pump for the op-amps and output transistor that needs AC .
Thanks a lot! Your video is very welcome: I bought that kit, and no documentation came along... The heatsink that I put was certainly too small , and I fried the D1047 during my first test with a load, I'm afraid... ;-( Will buy another transistor, with a big heatsink.
@@KristianLaholm Well, my learning curve is definitely not finished: yesterday I received a few D1047, and I've just fried one! I put an aluminium heat dissipator oversized, 10x10x3cm: that was obviously not enough!
@@KristianLaholm 0A right now... I ran it without any ampmeter, just for a small test with an old toy as load. It took about 5 seconds to fry. Now I changed again the transistor, I connected an ampmeter and I'll triple-check the components' wiring before switching on! Also, I'll put a more predictable load, like a LED panel or something. Not an engine like the ones in that old toy.
@@KristianLaholm Yes, it does! I've fried a total off three transistors today... One small resistor located on the corner left of the potentiometers is also getting very hot, even when there is just a small power running. Strange.
That sounds good but how would you work out the values in series? do you see what you have done by being clever, making yourself more work and that means I will have to drill another hole. thanks Bob
Hi, I was wondering about what power of transformer should I use. I know this requires maximum of 3 amps of current. I found a 24 vac 40 VA transformer for reasonable price. Is it going to be okay? I don't think the power supply will be able to provide 3 amps at 30 volts with it. Please let me know what you think.
hello friend, well all was going well with this project until what you mentioned happened! I acidently shorted the D1047 and now I am only getting full 30v at output.😞 I have several junk boards but I am not sure if there is any subsitute other than the D1047. Any thoughts about this? Thanks JW
+jwhiting352 Sorry to hear about your problem. In the old schematics I found they used the "old school" power transistor 2N3055 (different package) I would search for a general NPN-(power)-transistor with: V(CEO) > 60V (voltage across the transistor, D1047 is 140V) I(C) > 12A (current thru the transistor) P(D) > 100W And double check the pins (C,B,E) on the package. I hope that info is helpful :)
The circuit is designed for maximum 24V AC, over that and you will blow the op-amps. R2 is part of the negative voltage pump and with a to high input voltage you will dump a lot of power in it. Some recommend running the circuit with only 20Vac input voltage.
Check with a multimeter but normally the outer taps are the sum of the 2 voltages 12+12=24. But the circuit is sensitive to over voltage, feeding it with 24VAC is at the limit of some of the components if the transformer gives out more then 24V do not use..
I don't have the numbers in my head but if you want to skip the rectifiers and negativ voltage pump it might work. But I think the +DC should be up around 36V. You have to follow the schematics and connect to the correct points. Good luck :)
I don't think 12V is enough. I have learned more about the circuit over time and it needs 24V AC to function properly. You can try with 12V and nothing bad should happen more than to low voltage output.
Hi. I made this kit, but voltage have fluctuation, UP and down,never stable.. With no load, only if i want to setlle the voltage do desired voltage.. What can it be
Is the voltage rail stable (after the rectifying diods)? Is the setpoint voltage from the potentiometer stable? That is the things I would start checking.
Connect "COM" on your multimeter to "- OUT" then you can check voltage on the potentiometer. 0V on one side, i think 30V on the other side and mid pin is your setpoint.
@@KristianLaholm thanks i will check. All components is placed right, i check it.. I try to put capacitors on the 7812(i put 7812 for 12v fan) , to settle the fluctuation, but is The same.. Maibe if i remove 7812 from board and to Power the fan with other small transformer, It will help? I think because i use 40w transformer, can be the problem!?
The schematic is on the last page of the "English manual", link to the manual is on Banggoods page: www.banggood.com/0-30V-2mA-3A-Adjustable-DC-Regulated-Power-Supply-DIY-Kit-p-958308.html?p=AR22132858920201510H Or you can read about the "original" circuit here www.electronics-lab.com/project/0-30-vdc-stabilized-power-supply-with-current-control-0-002-3-a/
Hi. The heatsink i use is width 45mm, height 75mm and 25mm thick. The width (45mm) is the most that fits one the PCB. If you are going to pull high currents also use a fan.
My heatsink is cut from a bigger one so no problem. If you are going to pull high current over long periods I would put more time in to finding the "perfect heatsink and fan"
I ordered one like this one but it got lost somehow and they gave my money back.Too bad, i was waiting to fix my power supply.Maybe I will make it by myself.And that was so cheap.
Hello everyone: This circuit is quite good but the power transformer should not exceed 20V. The DC voltage in the supply (+ Vdc, -Vdc) in the operational ones when setting the 24V voltage exceeds the maximum values for which the manufacturer designed it. The maximum data sheet voltage says + Vcc - (- Vcc) = 36V, recommended 30V. It may work well for a while and then the operational ones will burn.
Hello can you test it on oscilloscope to see the ripple ?
Thank you for the video I have ordered one but was wondering the size of the board as this is not shown on the seller site.
Thank you if you can help
The PCB is 84x84mm and the height depends on the heatsink.
Thank you now when it arrives from China in a few weeks I know it will fit in the box I have
Yes this helps. thankyou.
Do you use 24V DC or 24V AC? It says that need 24V AC, but it's a little dificult get a 230V AC/24V AC transformer, it had to be toroidal.
In the PCB it alredy have the 4 diodes to convert to DC, are any problem connect the 24V DC instead AC?
+Francisco Madeira you must use AC voltage for the circuit to work.
There is a negative voltage pump for the op-amps and output transistor that needs AC .
Thanks a lot! Your video is very welcome: I bought that kit, and no documentation came along...
The heatsink that I put was certainly too small , and I fried the D1047 during my first test with a load, I'm afraid... ;-(
Will buy another transistor, with a big heatsink.
The magic smoke and deep fried components are a part of the learning curve :)
@@KristianLaholm Well, my learning curve is definitely not finished: yesterday I received a few D1047, and I've just fried one! I put an aluminium heat dissipator oversized, 10x10x3cm: that was obviously not enough!
@@pierrechevaliergeol What current are you running at? If you run at 3A it will get hot hot hot :)
@@KristianLaholm 0A right now...
I ran it without any ampmeter, just for a small test with an old toy as load. It took about 5 seconds to fry.
Now I changed again the transistor, I connected an ampmeter and I'll triple-check the components' wiring before switching on!
Also, I'll put a more predictable load, like a LED panel or something. Not an engine like the ones in that old toy.
@@KristianLaholm Yes, it does! I've fried a total off three transistors today... One small resistor located on the corner left of the potentiometers is also getting very hot, even when there is just a small power running. Strange.
I think when I get mine I will change the pot for a multiturn pot for voltage adjustment to make setting voltage out easy
You could also do two pot's "in series", one for course setting (high value pot) and one for fine setting (low value pot)
That sounds good but how would you work out the values in series? do you see what you have done by being clever, making yourself more work and that means I will have to drill another hole.
thanks Bob
Sorry for the extra work :)
For my longer answer look at my video th-cam.com/video/wpvxlcn7kVk/w-d-xo.html
what is the role of 100k pot, and what value should it be set
It is used to zero the output, use a voltmeter on the output and trim the 100k pot until you get 0V on the output.
ty
Hi, I was wondering about what power of transformer should I use. I know this requires maximum of 3 amps of current. I found a 24 vac 40 VA transformer for reasonable price. Is it going to be okay? I don't think the power supply will be able to provide 3 amps at 30 volts with it. Please let me know what you think.
Do you need 3amps at 30V? If not then use that transformer.
I didn't need full power thats why i chose to do the modifications I did.
hello friend, well all was going well with this project until what you mentioned happened! I acidently shorted the D1047 and now I am only getting full 30v at output.😞 I have several junk boards but I am not sure if there is any subsitute other than the D1047. Any thoughts about this? Thanks JW
+jwhiting352 Sorry to hear about your problem.
In the old schematics I found they used the "old school" power transistor 2N3055 (different package)
I would search for a general NPN-(power)-transistor with:
V(CEO) > 60V (voltage across the transistor, D1047 is 140V)
I(C) > 12A (current thru the transistor)
P(D) > 100W
And double check the pins (C,B,E) on the package.
I hope that info is helpful :)
Impressive! :)
Hi, My input ac voltage is 29v, and R2 which is 82ohms gets really hot, is it only BCS of the input voltage. Thanks
The circuit is designed for maximum 24V AC, over that and you will blow the op-amps.
R2 is part of the negative voltage pump and with a to high input voltage you will dump a lot of power in it.
Some recommend running the circuit with only 20Vac input voltage.
@@KristianLaholm thankyou so much for your inputs
what can be done about those two resistors getting very hot. switch them with larger ones or will they cope with the heat?
I have had no problems with the resistors.
I might need to take a second look at the problem :)
is it still working ? what about the o/p ripple ?
Hi, if I have a 12-0-12 center tap transformer, how do I connect it to the input? thanks
Check with a multimeter but normally the outer taps are the sum of the 2 voltages 12+12=24.
But the circuit is sensitive to over voltage, feeding it with 24VAC is at the limit of some of the components if the transformer gives out more then 24V do not use..
Hi, can I use 24VDC and -5VDC power sources to power it up?
I don't have the numbers in my head but if you want to skip the rectifiers and negativ voltage pump it might work.
But I think the +DC should be up around 36V.
You have to follow the schematics and connect to the correct points.
Good luck :)
Hi, I have a transformer 12V/4,2A. Is it enough to power the kit?
I don't think 12V is enough. I have learned more about the circuit over time and it needs 24V AC to function properly.
You can try with 12V and nothing bad should happen more than to low voltage output.
Hi. I made this kit, but voltage have fluctuation, UP and down,never stable.. With no load, only if i want to setlle the voltage do desired voltage.. What can it be
Is the voltage rail stable (after the rectifying diods)? Is the setpoint voltage from the potentiometer stable? That is the things I would start checking.
@@KristianLaholm Hi. After diode voltage is stable. Then set Point of potențiometer, how to check!?
Connect "COM" on your multimeter to "- OUT" then you can check voltage on the potentiometer. 0V on one side, i think 30V on the other side and mid pin is your setpoint.
@@KristianLaholm thanks i will check. All components is placed right, i check it.. I try to put capacitors on the 7812(i put 7812 for 12v fan) , to settle the fluctuation, but is The same..
Maibe if i remove 7812 from board and to Power the fan with other small transformer, It will help? I think because i use 40w transformer, can be the problem!?
@@Sandokans With a 40W transformer you can only take out 1A current or the voltage will drop.
The 7812 should't be a problem.
Do you have the schematic for the power supply?
The schematic is on the last page of the "English manual", link to the manual is on Banggoods page: www.banggood.com/0-30V-2mA-3A-Adjustable-DC-Regulated-Power-Supply-DIY-Kit-p-958308.html?p=AR22132858920201510H
Or you can read about the "original" circuit here www.electronics-lab.com/project/0-30-vdc-stabilized-power-supply-with-current-control-0-002-3-a/
Thank you!
Hi, what happen if you short the output?!
Hi, the power supply will then deliver constant current and the voltage will drop.
It will not burn up :)
Does this connect directly to 120V AC wall?
No, the max input voltage is 24VAC. You need a transformer 120VAC -> 24VAC, current rating 3A.
I am thinking of buying one of these but none of them seems to come with a heatsink, what size heatsink should I be looking for?
Hi. The heatsink i use is width 45mm, height 75mm and 25mm thick.
The width (45mm) is the most that fits one the PCB. If you are going to pull high currents also use a fan.
Do you know if it's possible to cut heatsinks to size?
My heatsink is cut from a bigger one so no problem.
If you are going to pull high current over long periods I would put more time in to finding the "perfect heatsink and fan"
I ordered one like this one but it got lost somehow and they gave my money back.Too bad, i was waiting to fix my power supply.Maybe I will make it by myself.And that was so cheap.
Sorry to here about your problems, I got my second kit :)
Try a new order and good luck :)
And you need a fan.