Batteries

Zman wrote:


Strictly speaking, you should have a removable key interlock somewhere on the power side of the controller. Many people use a shorted phono plug in homebrew controllers. My controller, and the ones we build in class, use a lot of household electrical components; they are cheap and easily handle the current loads of my non-relay controller. The interlock is half of a dual wall socket with a shorted power plug and the launch cable is an extension cord which plugs into the other socket. The female end of the extension cord plugs into a lamp cord tail with clips. A light switch is the main power ON/OFF switch. The most expensive part is a 30A pushbutton fire switch. A current limited LED, piezo buzzer, and small pushbutton all in series make up the continuity circuit (about 12 - 15ma through the igniter with a 13.8V lead acid motorcycle battery during test). We use a power strip at the pad end for drag races.
The controller/battery is very reliable and lights 7 motor BP clusters (Estes igniters) without a problem. It also fires copper bridgewire igniters (James Yawn style) and has even launched a modroc on bare nichrome.
--
Gary Bolles

summum jus, summa injuria est
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I really like the idea of a 'put in your pocket shorted out phono plug' and the piezo buzzer is also a great idea!
Thanks!
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Zman wrote:

I use three gel cells in parallel actuated through a simple relay. Will cook off anything. Try www.batterymart.com. Got mine for $9.99 each.
Kurt Savegnago
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Perfect!
    Bob Kaplow    NAR # 18L    TRA # "Impeach the TRA BoD"         >>> To reply, remove the TRABoD! <<< Kaplow Klips & Baffle:    http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org
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