mike ring writes:

Sounds like a good idea, but google and maplin came up dry (well on google
the first umpteen hits), so who's gottem; also what sort of suppressor -
how would I know what's in it from it's description, or to measure it

Maplin still sell them as 'contact suppressors', I found.

Their part no. RG22Y

Described as consisting of an 0.1uF capacitor in series with a 100 ohm
resistor (those values have been rule-of-thumb for this purpose since
before the dawn of time).

Also suitable as snubbers in SCR and triac circuits, they say, so
should be capable of handling large surge currents. Which you could
sometimes get when turning on power to a device which used this part
plus a bipolar LED instead of a neon.

Most LEDs seem quite happy with a high initial surge current which
quickly decays with a time constant of only 10 microseconds, but YMMV.

As for the bipolar LEDs, Digikey is still the only supplier I can think
of who sell these with two diodes of the same colour (thus being more
suitable for use on AC) as opposed to the common arrangement of one
red, one green, which would likely blend to produce some shade of
yellow if used on AC.
But others must sell two red or two green combinations.



--
Roy Millar, Use m o u l i n e t @