Re: [ATM] LED's and Diode Electronics

[Dominic-Luc Webb <dlwebb@canit.se>]

On Wed, 22 Jun 2005, Richard Schwartz wrote:

> Has anybody heard of using LED's for light sensors?    How does that work?

Actually, turning it the other way, I am not sure what is special,
exactly, about PINs. All LEDs I have tested, admittedly, not a lot,
have worked in reverse as photodiodes detectors. The made-for-the-purpose
PINs usually, but not always, work better. I know PINs are not
manufactured the same as LEDs, and this is maybe wherein the answer to
this question is.

Dominic-Luc Webb


> ----- Original Message -----
> From: "Dominic-Luc Webb" <dlwebb@canit.se>
> To: "Mark Holm" <mdholm@telerama.com>
> Cc: <atm@atmlist.net>
> Sent: Wednesday, June 22, 2005 3:08 AM
> Subject: Re: [ATM] LED's and Diode Electronics
>
>
> > On Tue, 21 Jun 2005, Mark Holm wrote:
> >
> > > > P21 tubes
> > >
> > > Is/wasn't the P21 a photomultiplier?
> >
> > Specifically, it was the RCA (Now Burle) 1P21. This was used from
> > about late 1940's to characterize UBV system. It was surpassed by
> > the RCA 931A and finally the RCA 931B. By all accounts, the 931B
> > was superior in terms of lower noise, etc. These are all side window
> > types. Most companies that produce these no longer list side tube
> > types at all on their web pages. I suspect a trend towards end window
> > types. As compared to a CMOS or CCD, these have peak sensitivity
> > at about 350-400 nm and are quite responsive to UV. Discrete single
> > photon counting is possible. There is another PMT that also has good
> > a good near IR response the that is an end Window type (EMI makes it,
> > but do not rememver number, EMI9451 rings a bell). I think there are
> > some people around currently using this for pulse counting UBVRI.
> >
> > I presently experiment with the 931A and 931B, which I can get on
> > Ebay for a few bucks. I am interested in scanning to get limited
> > spatial info, like repetetive cycling between a few nearby stars.
> >
> > Dominic-Luc Webb
> >
> > _______________________________________________
> > ATM mailing list http://www.atmlist.net/
>

_______________________________________________
ATM mailing list http://www.atmlist.net/