heat-detecting phototransistor?

Silicon converts photons into charge carriers down to about

1000 nm. If you want sensitivity at longer wavelength than that, you need a detector made with a smaller band gap material. Germanium goes down to about 1800 nm. Got any old germanium transistors you can open? Beyond that you need either photo diodes or photo resistors.

?Ref=26564&Site=US&Cat=33948587

Expensive!

-- Joe Legris

I know it's not much help, but they used to be available. I still have one that I bought back in the 60s that's in a TO-3 case with a transparent red covering. IIRC I got it to build a wireless audio link using a #47 lamp (no LEDs back then) as a transmitter. It'll detect a soldering iron from close range. I would do as John suggested and get a germanium power transistor cut off the top.

Mike

"The scientist is possessed by the sense of universal causation...His religious feeling takes the form of rapturous amazement at the harmony of natural law, which reveals the intelligence of such superiority that, compared with it, systematic thinking and acting of human beings is an utterly insignificant reflection." Albert Einstein (theoretical physicist)

Try these devices from Melexis. You can even order them from their webstore.

Robert

Na. Normal semiconductors such as silicon cut off at 1000nm relating to 1300 kelvin or such. Warmth such as body temp and a bit up is best detected with a thermopile.

Rene

--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

Might want to also give a look at photoresistors.

Dan