UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - BRY39

Diabolical Artificer · 11th Nov 2017, 7:23 am

Found a small bag of these the other day whilst trying to sort and list my tranny stash. They're described as a "programable unijunction transistor" or "silicon controlled switch", but unlike a bog standard SCR have four legs with a anode and cathode gate.

Surprisingly they were made up to 97 according to the Philips datasheet I found but mine are a lot older. Firstly how are they programmable or is that just spiel?

Second what were they traditionally used for? it says motor control ont said datasheet, but at a power diss of 275mW they wouldn't switch anything big, maybe not even a relay. I have visions of them in a pre IC adding machine or somesuch. I guess they're obsolete now but have yet to have a play with them.

Thirdly are they basically a SCR apart from having an anode gate that is.?

Andy.

11th Nov 2017, 7:23 am	#1
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,667	BRY39 - Solid state switches. Found a small bag of these the other day whilst trying to sort and list my tranny stash. They're described as a "programable unijunction transistor" or "silicon controlled switch", but unlike a bog standard SCR have four legs with a anode and cathode gate. Surprisingly they were made up to 97 according to the Philips datasheet I found but mine are a lot older. Firstly how are they programmable or is that just spiel? Second what were they traditionally used for? it says motor control ont said datasheet, but at a power diss of 275mW they wouldn't switch anything big, maybe not even a relay. I have visions of them in a pre IC adding machine or somesuch. I guess they're obsolete now but have yet to have a play with them. Thirdly are they basically a SCR apart from having an anode gate that is.? Andy. __________________ Curiosity hasn't killed this cat...so far.