[TenTec] Reverse Current Protection

[geraldj]

There are a some reliable, and yet energy efficient techniques. If you can stand 
voltage drop, a simple series silicon diode is effective. If you can't stand
voltage drop and want to keep it simple, a big shunt diode (anode to ground cathode
to plus input) and a supply fuse is effective. I use a 12 volt DC relay and two small
silicon diodes. One is in parallel with the coil to absorb inductive kick, and so 
has anode to negative, cathode to positive. The other is in series with that
combination, anode to supply cathode to relay coil positive. Then if the polarity is
correct, the relay gets power and I use its contacts to supply the radio.

Three ways, too simple for a kit. For my Corsair II I use an automotive cube relay.

For the shunt scheme go for a 15 or 25 amp diode and the lowest current rating
fuse that will run your transmitter.

73, Jerry, K0CQ


---------- Original Message -----------
From: Noel <noel5856z at gmail.com>
To: tentec at contesting.com
Sent: Thu, 26 Nov 2009 17:30:19 -0500
Subject: [TenTec] Reverse Current Protection

> Hi...I'm looking for some practical circuits to protect a 12V 2A 
> transmitter input. Are there any kits out there for sale?
> 
> Thanks.
> 
> Noel W1XB :-)
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
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------- End of Original Message -------