Yes, the COM should go to the + side of the relays such that each diode is
connected in parallel to the relay.

And as you mentioned, E goes to the ground.


Tal

> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Erik Jacobs
> Sent: Tuesday, June 18, 2002 12:42 AM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE]: interfacing a a relay (automotive world)
>
>
> > You may try the ULNxxxx chips. Go to DigiKey.com and search for 'uln'. I
> > think they have high gain (darlington) and already include the base
> > resistor and reverse voltage diodes.
>
> here is the techsheet for the ULN series:
>
> http://www-s.ti.com/sc/ds/uln2004a.pdf
>
> Now... I'm a little confused with the COM connection.  Would that go to,
> say, +12V, in the case where the relay coil is connected between +12V and
> output C?  And E would just get tied to ground?
>
> --
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>

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