What is the best method for remote control of a PSU just to control
switching it on and off? I was looking at data sheets for relays DPDT
but they all seem to require a holding current in the coil. Is there a
relay that latches on for a single pulse and will stay latched until a
second pulse is delivered? No coil holding current required from the
battery operated control signal (see schematic).Or is there an
alternative solution?

This is the schematic. The transformers load is a 1.5W LM317
regulator.

http://i12.tinypic.com/5yx94q0.png

Thanks for any suggestions.

On Aug 24, 9:16 am, Hammy <spa...@hotmail.com> wrote:
> What is the best method for remote control of a PSU just to control
> switching it on and off? I was looking at data sheets for relays DPDT
> but they all seem to require a holding current in the coil. Is there a
> relay that latches on for a single pulse and will stay latched until a
> second pulse is delivered? No coil holding current required from the
> battery operated control signal (see schematic).Or is there an
> alternative solution?
>
> This is the schematic. The transformers load is a 1.5W LM317
> regulator.
>
> http://i12.tinypic.com/5yx94q0.png
>
> Thanks for any suggestions.

Yes. They are called latching relays. Just about any large
electronics supplier sells these (see Newark Electronics, Digikey,
Mouser Electronics, etc.)

BRW

Hammy wrote:
> What is the best method for remote control of a PSU just to control
> switching it on and off? I was looking at data sheets for relays DPDT
> but they all seem to require a holding current in the coil. Is there a
> relay that latches on for a single pulse and will stay latched until a
> second pulse is delivered? No coil holding current required from the
> battery operated control signal (see schematic).Or is there an
> alternative solution?
>
> This is the schematic. The transformers load is a 1.5W LM317
> regulator.
>
> http://i12.tinypic.com/5yx94q0.png
>
> Thanks for any suggestions.

To begin with, eliminate NTC1, NTC2 and SW2.
You don't need a DPDT relay - single pole
is fine. And yes, there are latching relays
that are pulse operated and do not require
holding current.

Ed

On Fri, 24 Aug 2007 13:16:47 +0000, Hammy wrote:

> What is the best method for remote control of a PSU just to control
> switching it on and off? I was looking at data sheets for relays DPDT
> but they all seem to require a holding current in the coil. Is there a
> relay that latches on for a single pulse and will stay latched until a
> second pulse is delivered? No coil holding current required from the
> battery operated control signal (see schematic).Or is there an
> alternative solution?
>
> This is the schematic. The transformers load is a 1.5W LM317
> regulator.
>
> http://i12.tinypic.com/5yx94q0.png
>
> Thanks for any suggestions.

Use the pulse to energize the relay, but then get power to hold
the relay in from whatever it is you're powering. You'd need a little
circuitry to turn it off, say a gate where if power is on, then when
a pulse comes in, it gets inverted and interrupts the power to the
relay, turning it off.

Good Luck!
Rich

Thanks all for your suggestions.

I think I may have found a suitable latching relay at Digikey (not
much selection). I've noticed that they must be derated 75% for
non-resistive loads. The largest current carrying capacity is two amps
resistive load and 0.5A non-resistive.

I have a 14VAC 4.4VA Transformer coming next week hopefully Monday; I
can take some measurements to see if 0.5A_rms is adequate for sure
with safety margin. The LM317 is for 12V @ 0.125A.