Electronics > Repair

Help with ThaiKit Curve Tracer NOW W/ Calibrated Instrument OpAmp

(1/11) > >>

watchmaker:
I changed the to account for the improvements.  See  end of the thread.



I assembled this kit and made a nice enclosure, etc.  I have twice blown up signal transistors.  I feel like a watchmaking student who keeps testing his watch hoping for an improved result with no changes.  Neophyte.  But I like the puzzle to solve.

I have the schematic and I also looked up the Elektor article for the waveform information.

I verified the 2 ICs are ok and the same with the two transistors via substitution.  Both chips give out clean crisp signals.

I am leaving both jumpers open; small signal, NPN.  Both relays click when jumpers are added.  Checked all diodes out of ckt.

So I am doing something incredibly stupid.

Below are my waveforms at the collector and base inputs.  Emitter is zero.  I looked for the step signal from pin 9 of the 4024 chip but it is a simple square wave.  No transistor being tested.  I get the sawtooth at the scope horizontal output but nothing at the horizontal where the elektor article sez I should get a step (again, I have no transistor being tested/smoked).

I get that the emitter feeds the last opamp before the power transistors.

Can someone who has built this confirm my signals?

Conditions are :

No transistor
NPN
Small Signal

THANKS!!!











Jwillis:
Looks close to what I get with same settings. Sorry for the scope photo. Hantek USB doesn't work (piece of junk).  Pretty sure it's the same kit as yours. Added the signal from pin 9  of the 4024.

Jwillis:
Which small signal transistor are you testing. If I have one I'll see if I can blow it up.

Now you have me wondering what's going on. Large transistors test fine but as you, small signal transistors quickly get hot and fail. I don't use many small signal transistor in special applications. Mostly power applications. So I didn't notice the problem until now.
So given the evidence, your probably not doing anything wrong and there is an issue with the kit.

Jwillis:
Little update. The tracer works on most of my transistors. It won't test Darlingtons. BC517 Darlinton burns up and TIP142 (also a Darlinton) just shows a dot in the middle of oscilloscope and gets hot. Bost tested fine on a BSIDE ESR02 Pro.

watchmaker:
Thank you and I'll be damned.  I spent 3 DAYS on this following all the signals and marking the board with w/ the paths. |O

I just found this youtube.  He does an excellent job of explaining the design and its limitations.  He made me think I need to look at my 1 ohm resistor.


Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod