In article ,
John Rumm writes:
Sam wrote:

Sorry, what is a snubber circuit?

A circuit that helps dissipate the big spike of voltage that is
generated when you switch an inductive load. At its simplest it can be a
metal oxide varistor suppression type device (cheap at maplin).

A MOV is the wrong device to use for this, as the energy it
absorbs uses it up, until it runs out of capacity to absorb
any more and stops working. It's good for one-shot protection
or a small number of smaller incidents, but not for something
which is routinely expected.

All you need for a contact snubber is something which allows
the current to carry on flowing when the contacts open until
the reactive energy is safely dissipated. This is normally
done with a resistor which allows current flow and dissipates
the energy, in series with a small capacitor which blocks the
current flow at 50Hz.

e.g. [fixed width font]

| |
--/\/\/\---| |--
| | | |
| |
| / |
| / |
---------/ -------------


This is so common you can buy the resistor and capacitor
combined in one component (looks like a capacitor, e.g.
Maplin part RG22Y).

There is an example of a more sophisticated circuit used for protecting
the relatively delicate contacts of a reed switch shown he

http://wiki.diyfaq.org.uk/index.php?...nk#Flow_Switch

I would say that's a rather dubious circuit. The snubber isn't
protecting anything, but there isn't anything in that circuit
which needs protecting with a snubber anyway (except possibly
the triac, but a snubber across a triac is for a completely
different reason).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]