STD Nyokki's Lab Ⅴ

STD Nyokki's Lab Ⅴ


problem about TB-186840 diy power supply レギュレータ式 安定化電源の回路問題について

I bought power supply kit on the aliexpress.

The day the item was arrived, then I assembled it, and did working test.

But it didn't work, so I tried to find the problem.


At firtst, I suspected that some componets are broke down.(transistor or op-amp)

However all components ware working nomally.


At the second, I focused on npn-transistor D1047.

this transistor is used for main component for keep doing constant voltage and output amper.

And I measured at base voltage, so I found out this voltage was 0.09V.

I thought something is wrong, because it is applied some volotage.

So I check the voltage on D822.(Darlington connection)

It is wrong too.

I measured voltage at R3 resistor(1k),it was 0.09V.

and I noticed OP1 was warm, this is caused by over current.


So finally, I checked transistor 9014.

While I applied voltage the circuit, I measured voltage between collector to emitter.

It was short, so I removed the transistor.


and I resupplied voltage.

As a result, the power supply was working completely.


this is schematic for TB-186840.