Transistor as a diode - A use for your busted germaniums

[chromesphere]

Hey everyone,

Id read on here the idea of using a transistor as a diode before; a use for those busted transistors that you'd probably just throw out.

I thought i would give it a go today and see what happens.  Turns out, they work quite well as diodes!  Wish i hadnt of thrown out some of them out

Anyway, heres my usual video format report.  I've explain in the video how to do it, and also some sound samples of the transistors in a distortion plus.

Hope the information is useful to you, let me know what you think!

Paul

[stonerbox]

Sweet! I gotta try this.

[knutolai]

If you haven't seen it already I'm guessing you would be interested in this article:
http://www.muzique.com/lab/zenmos.htm

[Mark Hammer]

What has mystified me for a long time is how a germanium transistor can "work" as a diode but yet not function properly as a transistor.

What gives?  Do leaky GE trannies make for leaky diodes?

[chromesphere]

What has mystified me for a long time is how a germanium transistor can "work" as a diode but yet not function properly as a transistor.

What gives?  Do leaky GE trannies make for leaky diodes?

Thats what i thought.  What if one of the juntions has a physical defect, a gap for example.  Or is just broken in some way...

Maybe some transistors wont work?  I've only tried it on a few so far.

Paul

[LucifersTrip]

I just want to make a couple notes regarding the vid. You don't have to tie any lugs together and it will work with either BC or BE. There is no diode between CE. Just break the 3rd lug off.

I posted this a while ago to another forum, but it fits here...This is some of my vintage transistors that have either unusably high leakage, unusably low gain, a lug broken off, a short between lugs, etc...I have em labeled DOA and use em for diodes.

[chromesphere]

Is it wrong for a grown man to cry over that picture lucifer?

Thanks for the info!  I'll test it out tonight.  The leg tying method was admittedly the first attempt at it for me.

So...could you use 1 dud transistor as 2 diodes?

Paul

[PRR]

> how a germanium transistor can "work" as a diode but yet not function properly as a transistor.

Transistor is two junctions intimately coupled.

A very-leaky transistor has poor coupling.

A blown transistor usually has only one junction blown. (You have to experiment to find the un-blown one.)

It IS possible for a transistor to be blown so bad it won't even diode.

But historically, half-dead transistors were often used to boost the "transistor count" of low-price radios.

[Mark Hammer]

> how a germanium transistor can "work" as a diode but yet not function properly as a transistor.

Transistor is two junctions intimately coupled.

A very-leaky transistor has poor coupling.

A blown transistor usually has only one junction blown. (You have to experiment to find the un-blown one.)

It IS possible for a transistor to be blown so bad it won't even diode.

But historically, half-dead transistors were often used to boost the "transistor count" of low-price radios.

Thanks for that.  I well remember the way in which radios were advertised in terms of how many transistors they had.  I worked all summer of 1965 to buy myself a Mitsubishi radio that had eleven transistors    A 2SB172 cannibalized from that radio made the best-sounding Rangemaster I've ever been able to produce.  Sadly, I sold it to a guy, thinking "It's just one tranny.  I can make myself another."