a friend gave me an old (expired) ionization-type smoke detector.....inside, i found what i at first thought was a transistor, it wasn't.
it was a dual-gate thyristor........how do i use a thing like that?
ordinary (single-gate) devices, i know how to use........these things??.......duhhh!
oh, in case your'e wondering......it's inside the detection chamber itself......
does anyone have the schematic that relates to this application (that would be most helpful to me)

 

I am not familiar with a dual-gate thyristor. Do you have a part number for me to look up?

 

sorry, no......i wish i did.
but if you do decide to go after one yourself, you should be aware that those smoke detectors use a radioactive substance (Am 241).
this is 1 of the top 5 nastiest radioisotopic substances known to man.
fortunetly, it is contained in a capsule that you need not tamper with in order to get your hands on the thyristor (although, they are both located inside the ion chamber).......just be careful, and dispose of that Am 241 capsule properly at your local hazmat facility (and, for god's sake DON'T open that capsule!!!)

anyhow........the reason i ask about these devices is because they can be used to make a surprisingly sensetive ionization chamber-type radiation sensor.......hang on....the bulb just turned on.....back in a bit.

 

sorry, bulb's a bust.
anyhow.....i could be wrong about the thyristor......it could be a j-fet (totally different device, i know).......
or maby i've come across 2 entirely different systems for interfacing the ion chambers.
who knows.....stranger things have happened.

 

Maybe not a J-FET but a dual gate MOS-FET?

 

it was a dual-gate thyristor........how do i use a thing like that?

Silicon Controlled Switch. http://electronicsterms.com/scs-silicon-controlled-switch/

 

DENNIS......a most sincere thank-you!!!
i knew there was something special about those devices.......and now i know.
faster, potentially much more sensitive, faster response times.........ultra sweet!
as soon as i can, i'll post a coupla circuits using this device.

in the mean time......need a custom circuit board, but can't afford, or cannot get the materials needed to make one?
no problem!!!.......a peice of typing paper, a "bb" graphite pencil, a pen, some scrap copper, some drain cleaner, and last (but not least)
an old wall-wart (pref. 12V, 500mA, or better) with 2 gator clips.
procedure:......draw tour desired circuit traces on the paper using the pencil, mark holes and bridge points using the pen. (bridge points are small "jumper-type" disposable traces used to connect all the other traces together during the electrolosis phase
remember......draw in reverse of what you want....here's why:....the graphite side is your circuit side, that way, the copper is partially embedded into the paper.
when electrolosis is complete. just use a pin to make any holes you need, and don't forget to cut those bridge points!
then, just install your parts like on any other circuit board.
have fun (but stay safe).....HAPPY TINKERING, ALL!!!
l8er!....