Source for programmable unijunction transistors?

Mouser has gobs of them. Just search for unijunction on their web site.

--
Dave M
MasonDG44 at comcast dot net  (Just substitute the appropriate characters in the 
address)

Some people are like Slinkies.  Not really good for anything, but they bring a 
smile to your face when pushed down the stairs.

2N6027/6028 is the current generation of parts and available from Mouser, Digikey, etc. 2N4870/4871 and 2N2646/2647's are previous generations (but still available from Newark, etc.)

Tim.

2N4870/1 are not PUTs, they're UJTs. There was an even older one that was popular, but I can't remember the part number.. 2N6246? Ah, 2N2646. UJTs have a chunk of intrinsic Silicon between the two bases, wheras the PUTs are essentially an upside-down SCR. The application circuits are almost the same except the PUT needs two resistors to set the trigger point (and the parallel resistance of the two resistors sets the valley current).

Best regards, Spehro Pefhany

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speff@interlog.com             Info for manufacturers: http://www.trexon.com
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Many years ago I needed a UJT when they had just been invented and I couldn't buy one, so I simulated one with an NPN and PNP transistor. It might be possible to do the same for a PUT.

Leon

People still use those? Hey cool. Check out the Wiki

Part numbers to give you a start. Wow, I haven't heard about these in decades. I had fun with UJTs though, used them to build a strobe light. The UJT was in a relaxation oscillator to trigger the xenon tube.

A PUT is a simulated UJT. It's actually an upside-down SCR. You can make one from a pnp-npn transistor pair.

I doubt that anybody still makes real UJT's.

John

(still buying apostrophes in bulk)

Pro-electron part numbers

BRY61 BSV58

Jedec

2N6027 2N6028

RL