Fireworks Launch Box blows LED indicator status lights

ebeowulf17

Joined Aug 12, 2014
3,274
Was a long time ago when I heard it. I couldn't answer your question.

@MisterBill2 Sorry, I don't see a schematic.

Woke up this morning with this silly project on my mind. I modified my schematic as follows: I've added a main power switch and a MASTER ARM switch. There's also two more LED's. A yellow LED indicating power is applied, a red LED to indicate the MASTER ARM switch is armed and I've changed the originally red LED to green indicating a READY condition. I've also added a capacitor, 4700 µF to give the match a hell of a kick when the fire button is pressed. That will reduce the likelihood of a misfire due to a tired battery. It may even prolong battery life.

[edit] Maybe S3 should be 10 amps. Regardless, the descriptions of the switches are arbitrary as long as they are double throw. Any set of switches that will handle the task should be fine. {end edit}

View attachment 178725
The reason I suggested a master control between launch switch and ground is because all of your other switches also defeat the squib test (READY indicator.)

I've never built a system like this myself, but all the ones I've read about are designed to include a state where you can see the squib continuity status, but the launch switch is still safely disabled. That's the extra feature I was trying to achieve. In your system, as soon as you activate enough switches to check the ready status, you're also live and able to launch immediately. It seems desirable to be able to check whether your squib wiring is sound without risk of accidental launch.
 

MisterBill2

Joined Jan 23, 2018
7,041
Make S1 a key switch - one where the key is removable only when the switch is off. The key should be in the operators pocket when he is out near the fireworks. Now add a Schottky diode between the common of S2 (anode) and the common of S1 (cathode) so that when the POWER switch is shut off, it discharges C1. As it is, if the 'ARM' is left on and 'Power' is switched off, C1 might hold enough energy to set off the squib.

But considering what the TS is using as an igniter, R3 may need to be lower and/or C1 may need to be larger.
C1 will always discharge throughR3, R2, and the red LED. No need for anything else. And any maniac detonating a bomb will not be wanting any indicators as to what is happening. THAT is so very "MacGyver". Real bombs just explode.
 
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