At 12:58 PM 2/11/01 -0500, you wrote:

>
>You need a diode or a zener (reverse biased) across the coil, in that case.
>The zener should have a lower breakdown voltage than Vceo for the transistor,
>at the relay operating current.

Oops, I gave the correct voltage rating for a zener if it is across the
*transistor*. If it's across the *relay coil* it has to have a regular
diode in series and it has to be rated at less than Vceo - Vsupply - 0.6.

If it's across the transistor, it has to have a breakdown voltage of
< Vsupply, which should be obvious.

Best regards


=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads