Relay Box Connectors

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Well-Known Member
Dec 4, 2002
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OK guys, I've got my mock up of my relay launcher just about completed and tested. My last dilemma involves the connection at the relay box with the wires leading to the pad/igniters. As most of you have done, I'd like to have a connection there that would allow me to switch wire sets that have different type clips on them such as regulat alligator clips, and some set up for AT type igniters and possibly a clip whip.....Anyway, I've read and found components for the rest of the system that will allow for up to 30 amps, but I can't seem to find any plug type connectors (banana plugs, binding posts, whatever) that state this capacity. As for the Radio Shack components, I have used some simply because they are conveniently available, but I have just about lost my patience with that company. Seems like only random items list specifications on them, and of the 20 or so different employees I've run across in the last month, I believe one of them actually knew what the term resistance meant and that was because he was taking a 1st year electrical engineering course in college.

My preference would be to use a banana plug type connection, and I'm sure there are components out there, but I can't find them YET......Can someone help? I am open to other ideas there also.


Don't worry about the amp ratings for banana plugs in this application. I have passed 10's of amps at 40KV through banana plug connectors to recharge laser capacitors. Since your ignitor only draws high current for a second or less, you will not get any significant heating of the connector. For your leads use 18 to 14 gauge zip type lamp cord or speaker wire. It' cheap and readily available. has a lot of good stuff.

A standard dual banana plug is $1.20. You can connectorize any type of leads with this type of connector.

On your relay box use a pair of red and black 5-way binding posts ($0.65 each) spaced at 3/4". Not only will this mate with the above dual banana plug, but you can simply use stripped wire ends as well.

Here's a lifetime supply of 18 gauge zip cord. Price is $20 for 250 ft. You may do better at your local electrical supply or home cnter store.

These guys also have some of the best prices on 12 volt relays and relay scokets. $2.25 for a 40 amp relay and $2.00 for a wired relay socket.

!2 volt gell cells are cheap too. Shipping is only $6 no matter how big the order is.

Bob Krech
having built at least a dozen different relay ignition systems, I'll add my 2 cents to this one.
I've completely stopped using banna, phono or any other type "slide in" connectors. I've found a cheap alternative to amphenol connectors that still give a solid lock ring connection with positive nickel plated brass contacts. Radio Shack CB and Ham mic plugs. #274-001 4-pin Plug and #274-002 panel mount are both about 2.00 ea. and will outlast your launchers. they can be wired anyway you like and I've run as much as 24volts, 280amps thru them with no ill effect to the connectors...Fried the contacts on the power relay but hey it was an experiment:D You may be abel to see these connectors in this system pic
My latest relay box uses those Rat-Shak CB connectors for the control cable and banana plugs for the ignition leads. Works very well, plus the CB-Connector locks the control cable in place. I can reliably fire composite motors and 3~4 BP motors with this rig.
being an electrician in a past life I went with 40 amp Twist lock receptacle and plug for control cable connection. Over kill? of course it is!! but they were free out of my box of electrical crap.
Originally posted by stevem
being an electrician in a past life I went with 40 amp Twist lock receptacle and plug for control cable connection. Over kill? of course it is!! but they were free out of my box of electrical crap.

heh heh...

"Wee LIKE OverKill!!"

"Insert demented grin here"