All,

What about trying an LED used as a detector instead of an emitter?
I've used LED's in this fashion for RED, GREEN, YELLOW, and IR.
They won't be extremely sensitive, but they work.  You could always
Use an Op Amp after them if you need a stronger signal.

This too might be worth a try.

Just a thought.


						Regards,

						  Jim  

-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of Richard Prosser
Sent: Thursday, August 16, 2007 3:14 PM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Radiation sensor

Al Shinn wrote -
(snipped..)
> I don't know now where to get a bare silicon photo diode any more but 
> this approach would be some $1000 less then some previous pointers - 
> maybe < $20. Even Geiger counters can be in the $150 Or less range 
> http://www.blackcatsystems.com/GM/geiger_counter.html
> Geiger Counter Nuclear Radiation Detector Alpha Beta Gamma X-Ray
>
> Looking forward,
> Al Shinn
>


I used to make very basic phototransistors by cutting the top of the can
off the metal versions of the BC108/2N2222 types etc. (In general I
would then add clear epoxy for moisture protection). It may be worth a
try if you have any old metal can TO-92 bipolars lying around.

(Prior to that I had made them by scraping the paint off the old OC70
(?) Ge. bipolar parts. - but that's showing my age I think)

RP
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