TC1 users, some questions for you

[MBFX]

Bumping this old thread to chime in that my TC1 tester doesn't read JFETs reliably - 2N5485s read as either an inductor or a resistor, and only two of the pins are being read. I don't think it provides enough negative current to open the gate!

 

[joelorigo]

I recently got one of these and tried some various transistors. My questions is that if I leave a transistor in and test repeatedly, the hfe readings go lower and lower. Is this normal?

 

[benny_profane]

I recently got one of these and tried some various transistors. My questions is that if I leave a transistor in and test repeatedly, the hfe readings go lower and lower. Is this normal?

Is it Ge? If so, it will read higher if you’ve raised the temperature by handling it.

 

[andare]

I recently got one of these and tried some various transistors. My questions is that if I leave a transistor in and test repeatedly, the hfe readings go lower and lower. Is this normal?

In my case both leakage and hfe go down and eventually settle. It means the transistors are cooling down. Don't handle them with your hands, use tweezers. Or wait.

 

[joelorigo]

Ah I see. I was using both silicon and Ge.

Thanks!

 

[scotheath]

I just got one of these to test germanium transistors, it reads 2 diodes with every Germanium transistor I have ugh

 

[giovanni]

I just got one of these to test germanium transistors, it reads 2 diodes with every Germanium transistor I have ugh

I guess technically correct? Jokes aside, I never had such a problem. Very strange.

 

[scotheath]

I guess technically correct? Jokes aside, I never had such a problem. Very strange.

Yeah, It reads NPN and PNP silicon correctly

 

[Ginsly]

I just got one of these to test germanium transistors, it reads 2 diodes with every Germanium transistor I have ugh

I think that means that the hfe is really, really low - I could be wrong, though. I'd clean each transistor leg with alcohol and try again, just in case. Re-read entry #5 at the beginning of this thread too - lots of great info.

The TC-1 is useful, but outside of pinout I don't really use it for transistors, Ge or Si. I've found hfe readings for Si to be way higher than expected, and that's likely due to the test current; using a Peak DCA55 or RG Keen setup resulted in data that hews closer to both the datasheet and what I would expect certain transistors to be.

TC-1's Ge hfe/leak readings can be close enough to what Keen & Peak say (great comedy duo, btw), but mostly for lower-gain devices. It's pretty easy to set up a simple RG Keen tester, and I found it to be miles better than the TC-1 for hfe. The DCA55 is excellent, though.

Quick note - I also wouldn't count on the TC-1 OR the DCA55's Vf readings for Ge diodes, either - maybe Si too. They're WAY higher than simply checking with a multimeter, and lie far beyond what you'd expect - again, likely due to test conditions. You might buy Ge diodes that have a certain low Vf claim, then test them on a TC-1 and feel burned since they can read more than 50% higher than on a simple multimeter.

For me, the TC-1 shines for resistor and capacitor ballpark, transistor NPN/PNP/pinout, and LED testing/pinout.

 

[darwin999]

On high gain Si transistors (hfe>600 or so), it will usually show as two diodes.

Also, you might try putting it in calibration mode and/or removing batteries to reset it.
For calibration, short all three Probes, then short press the multi-function key - then the tester will automatically calibrate itself.

 

[scotheath]

On high gain Si transistors (hfe>600 or so), it will usually show as two diodes.

Also, you might try putting it in calibration mode and/or removing batteries to reset it.
For calibration, short all three Probes, then short press the multi-function key - then the tester will automatically calibrate itself.

Yeah I've tried that same resluts

 

[scotheath]

I think that means that the hfe is really, really low - I could be wrong, though. I'd clean each transistor leg with alcohol and try again, just in case. Re-read entry #5 at the beginning of this thread too - lots of great info.

The TC-1 is useful, but outside of pinout I don't really use it for transistors, Ge or Si. I've found hfe readings for Si to be way higher than expected, and that's likely due to the test current; using a Peak DCA55 or RG Keen setup resulted in data that hews closer to both the datasheet and what I would expect certain transistors to be.

TC-1's Ge hfe/leak readings can be close enough to what Keen & Peak say (great comedy duo, btw), but mostly for lower-gain devices. It's pretty easy to set up a simple RG Keen tester, and I found it to be miles better than the TC-1 for hfe. The DCA55 is excellent, though.

Quick note - I also wouldn't count on the TC-1 OR the DCA55's Vf readings for Ge diodes, either - maybe Si too. They're WAY higher than simply checking with a multimeter, and lie far beyond what you'd expect - again, likely due to test conditions. You might buy Ge diodes that have a certain low Vf claim, then test them on a TC-1 and feel burned since they can read more than 50% higher than on a simple multimeter.

For me, the TC-1 shines for resistor and capacitor ballpark, transistor NPN/PNP/pinout, and LED testing/pinout.

Yeah I have the Keen setup on my breadboard, just thought this would be handier than doing the simple math