Quick and dirty transistor tester - UK Vintage Radio Repair and Restoration Discussion Forum

Mike Phelan · 26th Nov 2006, 10:24 am

I have always had a pile of nondescript transistors gleaned from various places, mainly from various scrap domestic stuff, printers and the like.
Most of them are just smell signal devices, and all I need to know are if it is PNP or NPN, whether it works, and what the connections are.
Sure, I could look up the numbers on the internet, but that takes time.

A bit of research came up with

http://www.talkingelectronics.com/html/Combo-2.html

This is an ingenious design based on ring counter that determines which connection is the base, and whether PNP or NPN by seeing if the base has two "diodes" connected to the other two leads.
Another stage shows if O/C or S/C, than finally, there is a rudimentary hFe tester with a pot for base current.

I find it quite useful now; knocked up from stripboard (look away

) and used a PP3 instead of 4 x AAA.

[IMG]http://static.***********/105/306393467_f3772258e6.jpg[/IMG]

Barrel distortion is in the picture - the case is not bulging!!

Sideband · 26th Nov 2006, 5:47 pm

That's a useful gadget! I've seen something like it in operation before but never seen a circuit. I feel a project coming on......!

Rich.

Mike Phelan · 26th Nov 2006, 6:52 pm

If anyone wants a copy of the panel design, PM me with your email address.

26th Nov 2006, 10:24 am	#1
Mike Phelan Dekatron Join Date: Nov 2003 Location: Near Leeds, West Yorkshire, UK Posts: 4,609	Quick and dirty transistor tester I have always had a pile of nondescript transistors gleaned from various places, mainly from various scrap domestic stuff, printers and the like. Most of them are just smell signal devices, and all I need to know are if it is PNP or NPN, whether it works, and what the connections are. Sure, I could look up the numbers on the internet, but that takes time. A bit of research came up with http://www.talkingelectronics.com/html/Combo-2.html This is an ingenious design based on ring counter that determines which connection is the base, and whether PNP or NPN by seeing if the base has two "diodes" connected to the other two leads. Another stage shows if O/C or S/C, than finally, there is a rudimentary hFe tester with a pot for base current. I find it quite useful now; knocked up from stripboard (look away ) and used a PP3 instead of 4 x AAA. [IMG]http://static.*********/105/306393467_f3772258e6.jpg[/IMG] Barrel distortion is in the picture - the case is not** bulging!! __________________ Mike. Last edited by Station X; 26th Nov 2006 at 10:38 am. Reason: Link fixed. Appears to be case sensitive.

26th Nov 2006, 5:47 pm	#2
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,572	Re: Quick and dirty transistor tester That's a useful gadget! I've seen something like it in operation before but never seen a circuit. I feel a project coming on......! Rich. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

26th Nov 2006, 6:52 pm	#3
Mike Phelan Dekatron Join Date: Nov 2003 Location: Near Leeds, West Yorkshire, UK Posts: 4,609	Re: Quick and dirty transistor tester If anyone wants a copy of the panel design, PM me with your email address. __________________ Mike.