Re: Help with 12 volt rocket igniter

In article
<4a1cc053-531a-4420-ae1e-a65603df2d08@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
ULB <ultralightbackpacker@xxxxxxxxx> wrote:

When I push the launch button all LED die off If an igniter is in
place). I even tried using 12 volt incandescent lights minus the
resistors and same problem. I am assuming this is because of the
"short"? Is the above by design? Perhaps I mis wired it but I do not
believe so. I played for 12 hours today. LOL.

Second question: While trying to mimic the Igniter (I went through 8
of them), I just used a jumper cable, same issue, all lights go off.
However, if I leave the jumper on, boy does the battery (12 AA 1.5
volt) get hot. To the point I can tell something is definately
amiss. I went back to Radio shack and got some diodes. Didn't fix
the issue. I "Worry" about this as the final solution would be to use
my car battery, and I certainly don't want to fry anything in the
vehicle

As Ed said, 12 1.5V batteries are 18V, not 12. Cut back to 8 (or 10 if
nicad/nimh rechargeables at about 1.2V each).

It is normal for the the LEDs to drop out. In my version, LED-G will
definitely drop out (SW2 shorts it) and LED-R and the piezo may or may
not drop out (but will definitely dim) depending on the battery source
impedance (internal resistance of the battery + resistance of the wires
leading from the battery) and resistance of the wires running to the
launch pad, as well as the ignitor resistance. When testing with no long
wire (which adds some resistance) to the launch pad and AAs
(particularly non-rechargeable ones, which have a relatively high source
impedance) as the battery, I'd expect those to both drop out as well.

A light bulb is a better test item than a dead short/jumper.

With a car battery as the source and long wires out the launch pad, I'd
expect LED-R and the piezo to stay on in my version - but it's not a big
deal if they don't. The main thing to check for correct/safe operation
is that nothing happens with the test bulb if SW1 is not on (pressing
SW2 should have no effect), and nothing happens with the test bulb if
SW2 is not pressed (SW1 on or off), and that the test bulb lights if SW1
is on and SW2 is pressed.

Use a lighter plug to connect to the car - that will put a heavy fuse in
line with the battery supply, which I neglected to draw.

In any case, SW2 should not be held on for more than a few (1-5)
seconds. If the ignitor has not gone by 5 seconds, something is wrong.

--
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.