Serge Auckland wrote:

"Ian Bell" wrote in message
...
I am trying to select a relay for a delayed HT switch (which will also
discharge the HT when off). Most relays I can find have contacts rated
at 250VAC which translates into a peak of about 350V. However, data is
scarce on what dc voltage these relays can switch. So far I have found
only one that gives a dc current versus voltage curve and that stops
at 210V dc (and 200mA) and I really want to be able to switch up to
350V at up to 200mA. The rest just give a dc voltage at max current
value.

So, I am guessing that this problem has been faced before and there
are relays that are known to work fine in this application. Any
recommendations?

By the way I prefer a 5V coil.

Cheers

Ian

Use a Triac. The gate can then be triggered by a low voltage relay like
a reed. I built such a delay into a valve amp I designed many years ago,
which used a SS bridge rectifier, and I wanted to delay the HT until the
heaters had warmed up. Used a Unijunction transistor timer to create a
30 second delay, then that closed the reed relay which fired the
Triac. 1000 volt 1 amp or more Triacs are cheap.


That sounds like a good idea.

Thanks

ian
S.