> -----Original Message-----
> From: piclist-bounces@mit.edu 
> [mailto:piclist-bounces@mit.edu] On Behalf Of Bob Axtell
>
> Spehro Pefhany wrote:
>> A diode across the coil has been suggested, and is the 
>> simplest way of handling the coil inductance. A 1N4148 
>> is fine for any relay you'd be likely to use.
>
> Use a Transorber, Varistor,  or TVS device, with a voltage 
> rating just above the voltage being applied to the relay or motor. 
> If need be, just trust me on this one,  its the truth. Go to the
> technical documents page of any transient voltage suppressor 
> maker and you will understand what people are doing. These were 
> originally invented by GE.

I tend to think a 1N4148/4448 will be good enough for low
duty relays since the coil resistance is fairly big in
this case. But I must agree with you that TVS/Varistors
are much better protection device than a simple and
cheap 1N4148/4448.

Regards,
Xiaofan

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