t7 transistor tester

[makisushi]

At what voltage does the a t7 tester test a transistor? In this picture I have a NOS NPN silicon darlington Motorolla mpsa serie (I think it's a 13 but not sure), it reads 196 000 for gain... should I see a big difference between 1-5v or it's more notable a higher voltage?

 

[makisushi]

I think this is the one

 

[makisushi]

or maybe it's because of the low Ie...

 

[GAStan]

Do you have a voltage meter? You should be able to check the voltage while testing a transistor.

 

[makisushi]

Lol well that's a good idea . It's moving quickly and I don't know if the multimeter affect the t7 but it peaks at 3v

 

[jwin615]

See if you have a min max feature on your DMM. If so. use that
I can try to test mine whenever I get home tonight but iirc there's a 3.7v lion battery inside and it also displays the voltage on boot so it won't exceed those voltages

 

[GAStan]

This is the best spec sheet I found with a quick look. I'm guessing 4.5vdc for transistors up to 30v for zeners but could be wrong.

 

[GAStan]

iirc there's a 3.7v lion battery inside and it also displays the voltage on boot so it won't exceed those voltages

It could have a charge pump or series of voltage doublers.

 

[jwin615]

It could have a charge pump or series of voltage doublers.

Almost certain I've measured this at around 3.3v

 

[makisushi]

well, max is actually around 5.3V 5.4V on my DMM. Battery is at 4.03v on the T7. Also, I don't think it was the same transistor this one is a Motorolla MPS A12 . gain is arround 110k

 

[GAStan]

Almost certain I've measured this at around 3.3v

I'm not doubting you at all.

I was just pointing out it is possible to have a higher test voltage than battery voltage. I've built a couple of pedals with 18vdc available from a 9vdc input using charge pumps. Old battery powered tube radios (such as those used in cars) used voltage multiplier circuits to get high voltage required to operate tubes.