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Multiple relay controller

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ayryq

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I've been trying to adapt the circuit found at thrustgear.com for multiple relays - I figure I can use a DB-9 cable and get control of four pads (or engines) with continuity.

I've been puzzling over the schematic (found at http://thrustgear.com/relayer.pdf) and I'm a little puzzled by the stuck-relay alarm (referenced at http://www.rocketryforum.com/showth...y-launch-controller-plans&p=154172#post154172). It looks as if it will only sound if the igniter clips are shorted - or if an igniter is installed.

Am I missing something?

I'm attaching my attempt at scaling up the circuit to multiple pads.four-channel relay launch control circuit.jpg
 
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jderimig

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Have you sent an email to John DeMar at thrustgear.com with your questions? I am sure he can help you.
 

ayryq

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I think I figured it out on my own - looks like I'm right, but because of the resistor the igniter won't actually fire - so the buzzer will go off only once the new igniter is hooked up, but the rocket won't go up in your face :)
 

jderimig

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I think I figured it out on my own - looks like I'm right, but because of the resistor the igniter won't actually fire - so the buzzer will go off only once the new igniter is hooked up, but the rocket won't go up in your face :)
If the switch is in test mode, the stuck relay alarm with indicate but not fire the igniter. But when you switch to ARM the igniter will fire if the relay is stuck. The stuck relay alarm warns you not to flip the switch to arm.
 
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