Well, it turns out I bought another new kit from another dealer.
I meticulously measured each component with three different multimeters before positioning them on the pcb to make sure and also bought more components because each kit is usually missing some.

I mounted it with great care too and the result was the same. R1 gets too hot, and I didn't see him much either.
to this component or to several more, so I've been researching more sites and what's going on.
I understand that the kit that is normally sold is the original version of the design, and that it is really delicate and presents some youth problems that have been replaced in later versions . . . I have seen so many versions and modifications that I have a headache, but I do not want to depart from the philosophy of the first, with components at low cost and therefore I want to continue improving the original, as cheaply as possible.

There are versions with an AC transformer of 28 to 30v and of 5 or 6 amps. . . but they are far from what we are looking for, something valid for those who start, in cost, means and execution.
Pd: In addition I made a stupid shortcircuit with the Q2 heat sink (with multimeter clamps) and the Vout negative and the new KIT is broken. . .perfect.

 

yes, but the InPuT is the oUtPuT of another voltage source (and it -- the R1 helps to form the adt.-l -5V here . . . and is kind of regulating the intake from rectifier)
((((i know "my truth is bigger than your truth ? my god has bigger than your's"))))
also it's absolute priority to make others look incompetent and not provide any solutions yourself (because then you migh be wrong and can't criticise the others) = your absolutely right (well if you'd say anything . . . such) - - - - it's an old wisdom divide et impera -- if you set the others to fight amongst themselves (not incorporate) then you can take the control (well if you can) . . . as always -- it's not about getting problems solved , but gaining the power (privilegs ... easy/secure life) . . . it's very animal built in bug -- ? to remain in this lousy world as long as possible ? . . . ? the last one stnding/falling is/was the winner ? - Hurray!

 

Well, it turns out I bought another new kit from another dealer.
I meticulously measured each component with three different multimeters before positioning them on the pcb to make sure and also bought more components because each kit is usually missing some.

I mounted it with great care too and the result was the same. R1 gets too hot, and I didn't see him much either.
to this component or to several more, so I've been researching more sites and what's going on.
I understand that the kit that is normally sold is the original version of the design, and that it is really delicate and presents some youth problems that have been replaced in later versions . . . I have seen so many versions and modifications that I have a headache, but I do not want to depart from the philosophy of the first, with components at low cost and therefore I want to continue improving the original, as cheaply as possible.

There are versions with an AC transformer of 28 to 30v and of 5 or 6 amps. . . but they are far from what we are looking for, something valid for those who start, in cost, means and execution.
Pd: In addition I made a stupid shortcircuit with the Q2 heat sink (with multimeter clamps) and the Vout negative and the new KIT is broken. . .perfect.

And I now realize that I forgot to answer the question as to what kind of light bulb to put in series. I have seen mostly 6 volt bulbs, either 150mA rated (#47), or sometimes 250mA rated, which I am not sure about the number of that bulb type.

 

Hi all,ive built one of these,works ok except when the cc led comes on it cuts the output to 0v,it doesent regulate the current,its all or nothing,any ideas where to look?

 

watch the video til the end,thank you all ,i had the same problem trying to shortcut the input with a DC supply,you need a 24v transformer.

 

Hello, i dont know if anyone will read this but my problem with this is that when i connect everthing and power it up the voltage is about 26.6V and goes to 27.6 when the potentiometer is turned all the way. I noticed that the 1k ohm diode (next to the D882 transistor) is heating up. Has anyone got any suggestions?

 

OK, I read this post just now and I realize that this thread started in 2019. And the post before was a year old. So do you have another one of these power supply kits? Evidently quite a few of them have been sold. Or has the project set for a year and now being revisited?
This is a quite complex circuit and certainly there are many places where an error could be made in assembly.
What sort of test engineer are you? This project would be a bit of a challenge for most folks who are not electronic engineers.

 

I worked on this circuit 16 years ago at www.electronicslab.com. Then it was a defective kit from Greece.
1) The TL081 opamp Q2 is destroyed by over-voltage as mentioned in our thread here. The TL081 maximum allowed supply is only 36V but the circuit needs a much higher voltage.
The transformer must be 28V minimum to get 30V at 3A from this project. Without a load the transformet might produce 29.5V which makes a rectified +40.3V and my negative supply is 1.4V so Q2 is powered with 41.7V which is less than its maximum allowed voltage of 44V. TWO output transistors must be used on a large heatsink to share the heat.
I used TLE2141 opamps because their maximum allowed supply is 44V and Q2 works fine with only 1.4V for the negative supply (the TL081 must have at least 4V for its negative supply).
2) I increased the value of C1 to 12000uF.
3) Like mentioned here, I used 5mA zener diodes instead of the ones in the kit that must have a much higher current.
4) I increased the power ratings of a few resistors so they don't burn up when the output of this project is 3A.

The Chinese copy is of the original old defective kit.

 

I worked on this circuit 16 years ago at www.electronicslab.com. Then it was a defective kit from Greece.
1) The TL081 opamp Q2 is destroyed by over-voltage as mentioned in our thread here. The TL081 maximum allowed supply is only 36V but the circuit needs a much higher voltage.
The transformer must be 28V minimum to get 30V at 3A from this project. Without a load the transformet might produce 29.5V which makes a rectified +40.3V and my negative supply is 1.4V so Q2 is powered with 41.7V which is less than its maximum allowed voltage of 44V. TWO output transistors must be used on a large heatsink to share the heat.
I used TLE2141 opamps because their maximum allowed supply is 44V and Q2 works fine with only 1.4V for the negative supply (the TL081 must have at least 4V for its negative supply).
2) I increased the value of C1 to 12000uF.
3) Like mentioned here, I used 5mA zener diodes instead of the ones in the kit that must have a much higher current.
4) I increased the power ratings of a few resistors so they don't burn up when the output of this project is 3A.

The Chinese copy is of the original old defective kit.

I had not guessed that anybody would market a fundamentally defective product, evidently I guessed wrong. Possibly the circuit is OK when it it is assembled with a 12 or 16 volt supply.and delivers a maximum of 15 volts at a maximum of one amp. Doing the detailed analysis of the circuit is a "big deal" as to the effort involved, more than I was up to on a cold and rainy Sunday afternoon.

 

The kit from Greece was sold around the world, I saw some in a shop here in Canada.
It was advertised as producing 30VDC at 3A when powered with a 24V transformer but its max output was only 26VDC due to voltage drops and at 1.5A before some parts overheated.