On Sat, 2008-01-12 at 21:51 +0100, dd3ly@arcor.de wrote:
> I need the circuit breaker for my Century 22 which I am buying these days.
> Ten-Tec supplied a circuit breaker named 1179 with 5A continuous current
> and 6.75A trip current which was made by AIRPAX. It was a fast type, therefore
> magnetically released, not thermal or hydraulic, as it should protect the
> final amp.
> Perhaps you know the AIRPAX type name oe a sufficient equivalent.
>
> If I really should not find one, I think of home brewing a solid state
> circuit breaker
> with a power MOSFET with low Rdson and a rail-to-rail operational amplifier.
> Maybe there is someone who has done this already. I would appreciate any
> suggestion.
That should work.
For my Corsair II, knowing that a fast blow fuse can carry 125% of
nameplate continuously, I've used a 16 amp type MTA automotive fuse in
place of the circuit breaker. So far the fuses have blown faster than
the PA transistors. So for your rig, I'd use a 4 amp fast blow fuse.
The solid state fuse should work and there are probably integrated
circuits made for the purpose. I know there are some made to sense
current in the positive supply line.
One could also use a FET and some reference to operate the FET as a
current source that limited current to 5 or 6 amps but when the load was
smaller would keep the FET saturated for minimum (20 millivolts) voltage
drop.
While there is only one Airpax breaker to fit the 1179 description,
actually Airpax makes many breakers with the same fast operating works
with different cases, mountings, and handles. They can be found on the
Airpax web page, sometimes on web pages of their distributors. Needs to
rated for DC as well as the fast operating time characteristic.
>
> 73 from the Baltic Coast of Germany
> de
> Andreà DD3LY
>
73, Jerry, K0CQ
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|