Topband: 12 volt relays

[Missouri Guy, N0TT]

> That is an easy solution. But I think you missed the point that I 
> was 
> attempting to keep my entire system powered by a single 12 to13.8V 
> storage battery for emergency purposes. Then the task is not quite 
> so 
> direct. I think the thread was also useful because it  makes 
> potential 
> users of a  seemingly acceptable circuit aware that it doesn't 
> perform 
> to the level expected.

Thomas,
I got into the thread a little late....It's been awhile since I've
looked at the circuit I've used which operates a 24-v relay
from 12v, but as I remember it and FWIW, I use a DPDT 
switch and charge up two capacitors in parallel, then when 
I want to switch the relay, the two caps are connected in series
by the switch which then pulls up the relay.  I have a "keep alive" 
resistor that keeps the relay operated for as long as needed.  Obviously
it's not a circuit that would be any good for fast "QSK" switching.
I used it to remotely switch a matching circuit on my "Dakota Special"
vertical.  

One of the circuits I saw referred to on the net that used a transistor
was a nice piece of work...very clever design.
> 
> As I mentioned in one of my earlier post, I am pursuing the boost 
> regulator approach and now have a couple of  MC33063AP ICs on order. 
> 
> I'll provide the schematic to those who have expressed interest in a 
> 
> circuit after I've had a chance to build it on the bench.

I'd like to see that.

73,
Charlie, N0TT