Using a power mosfet to select from various power sources for HFrig
 

Anything I should be concerned about with my plans to use a power mosfet
to choose amongst various 14V sources to power an IC706. This is for
automotive use. I want to use my deep cycle batteries while the engine
is off, and use the engine/battery/alternator while the engine is
running. Thought I'd use a couple of big mosfets to select one or the
other.

thoughts?

- jim

Tried it. Save yourself some grief and use relays ;-)

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca

Tried it. Save yourself some grief and use relays ;-)

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca

Care to expand a bit on this?

Gregg wrote:
Tried it. Save yourself some grief and use relays ;-)

Care to expand a bit on this?

Gregg wrote:
Tried it. Save yourself some grief and use relays ;-)

Behold, James W signalled from keyed 4-1000A filament:

Care to expand a bit on this?

Sure!

I found that the RDSon was too high with most MOSFET's. The best I could
attain was a 1/2 volt drop at 1 amp load. When the CB linear came on, it
increased the drop to 6 volts (60 amp draw).

So, I went to the auto wrecker and got a couple of 30 amp relays and a 100
amp contactor for the job and it worked perfect.

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca

Behold, James W signalled from keyed 4-1000A filament:

Care to expand a bit on this?

Sure!

I found that the RDSon was too high with most MOSFET's. The best I could
attain was a 1/2 volt drop at 1 amp load. When the CB linear came on, it
increased the drop to 6 volts (60 amp draw).

So, I went to the auto wrecker and got a couple of 30 amp relays and a 100
amp contactor for the job and it worked perfect.

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca

On Sun, 07 Mar 2004 22:33:12 -0800, James W
wrote:

Anything I should be concerned about with my plans to use a power mosfet
to choose amongst various 14V sources to power an IC706. This is for
automotive use. I want to use my deep cycle batteries while the engine
is off, and use the engine/battery/alternator while the engine is
running. Thought I'd use a couple of big mosfets to select one or the
other.

thoughts?

Why not a pair of BIG Schottky diodes?

On Sun, 07 Mar 2004 22:33:12 -0800, James W
wrote:

Anything I should be concerned about with my plans to use a power mosfet
to choose amongst various 14V sources to power an IC706. This is for
automotive use. I want to use my deep cycle batteries while the engine
is off, and use the engine/battery/alternator while the engine is
running. Thought I'd use a couple of big mosfets to select one or the
other.

thoughts?

Why not a pair of BIG Schottky diodes?