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Relays, Batteries and clips

Hello All:

I want to convert my launch controller to a relay system. I currently have a 7Ahr sealed lead acid battery that sits at the launch button end of the system. I want to put the battery and realy at the pad end. I have a few questions for the hive:

  1. Is it OK to use the same battery power to fire off the relay and do the launching or do I need a separate battery to fire the relay? I intend to start doing clusters (initially 3x 18mm estes motors only) so there will be multiple ignitors to deal with.

  1. I know it's been posted before but is the prefered ignitor clip the Mueller BU-34C?

3A. Are banana plugs (15 amp rating) ok for hooking up ignitor wires to a relay box? 3B. Are dual stackable banana plugs (also 15 amp rating) ok for hooking up clip whips for clusters?

  1. What is a good inexpensive automotive relay to use for a launch controller when you want to cluster estes motors?

Thanks

-- nOrM njdjr@earthlink_delete this part_.net

Reply to
Norm Dziedzic
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That's what my relay boxes do. if you have weak batteries, the relay will drop in and out under the fire current load. But it wouldn't ignite the rocket anyway.

Yes. Unless you've got twisted leads and want the aligator clip, 30C.

Yes and Yes. Been using nothing but for a long time now.

I don't have part numbers handy, but anything with a 10+ A rating across the contacts should do. Match the relay rating to your batterys short circuit current capacity. IIRC you're not too far from Tri State electronics - I'm sure they've got something there that will work fine.

You can find my relay launcher post at

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Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Reply to
Bob Kaplow

Thanks Bob, Great write up.

and ... yes, Tri State is geek heaven up here in the near northwest suburbs of Chicago ;-)

Reply to
Norm Dziedzic

Mine does that too. A side benefit is that it also indicates a short.

Reply to
Darren J Longhorn

Chicago ;-)

What Radio Shack can only dream of being. Makes me miss Crash Electronics that used to be near my office... Hi Gordon!

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Reply to
Bob Kaplow

You need more power! Then on a short, you can melt the lead wires!

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Reply to
Bob Kaplow

;-)

On balance I prefer the buzzing of the relay coil.

Reply to
Darren J Longhorn

A 10-Amp autoreset thermal breaker in series with the igniter leads will protect against long-term (melting!) shorts and save on battery energy. They have no affect on the current available for normal ignition... it takes several seconds of a dead short to heat up the breaker. It kicks back in within 20-30 seconds, time enough to recycle the launch attempt. The breakers are around a couple bucks at an autosupply store. They usually come with quick-on tab terminals. Online,

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has them for a buck, I think. They also have a $5 12V-30A relay I've used for many applications (including all the relay pad boxes used by MARS(NY)).

-John DeMar Here's my launch system design page:

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Reply to
John DeMar

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