hi
im trying to find an alternative to a st-4 diac. its odd as its trigger voltage is around 7 v as opposed to 30v of normall diac. they seem to have long since become obsolete does anyone know of an alternative.

 

Have you tried looking on Digi-Key?

 

Either you didn't read his entire post, or you didn't read the datasheet. He's looking for a 7V breakover, and the HT-XX parts are about 32V minimum.

I read the data sheet, I'm confused, thought he was looking for a 30v trigger.
thanks for clearing that up Ron

 

I read the data sheet, I'm confused, thought he was looking for a 30v trigger.
thanks for clearing that up Ron

I deleted the post that you were responding to, just before you posted. I'm confused, because the first time I clicked on your link, it came up with something like HT-35. Now when I click on it, it gives me a big table of parts, and there are some silicon bilateral switches near the bottom that are around 7-9V. These are 3-terminal devices, so they wouldn't work for replacement, or in an existing design.

 

I deleted the post that you were responding to, just before you posted. I'm confused, because the first time I clicked on your link, it came up with something like HT-35. Now when I click on it, it gives me a big table of parts, and there are some silicon bilateral switches near the bottom that are around 7-9V. These are 3-terminal devices, so they wouldn't work for replacement, or in an existing design.

That's weird, there were no bilateral switches on that page
anyway, I just replaced the link with the homepage

 

i was sebt this as a poss alternative

 

Have you looked at SBS? The datasheet has application information.

 

thanks
its a new one to me will have to learn how to use it

 

I have 7 of the ST-4, but the center pin has been cut very short. Just found them while sorting out my mess. Probably way too late of reply.

 

No, not late at all.
You have introduced me to a device I wasn’t familiar with.

Thanks for that.

 

https://uk.farnell.com/powerex/bs08d-t112/bilateral-switch-9v-1a-to-92/dp/9109633?st=bs08
https://uk.farnell.com/solid-state/2n4991/sidac-1a-to-92/dp/2630601