Resistors as ignitors

[Astronot]

I was reading an article about electronics and Pyro in a Fireworks publication, and in this article the author makes the claim that he has used resistors as ignitors to electrically fire fireworks.

I was wondering if anyone has done this before in rocketry. Seems feasible to me. He said he used 3.9 ohm resistor in a 12 volt firing system. The idea being that you overload the resistor and cause it to heat up rapidly.

Food for thought.

David

 

[thomas]

Actually the contrail hybrid motors come with igniters which use commercial resistors, see for example this manual:
https://www.contrailrockets.com/Documents/75mm Instruction Manual.pdf

The benefit is of course reproducibility , but the wired resistors are quite large.

 

[Tonimus]

I have a bunch of resistor igniters. They are very large. Some are probably close to 1/4" across.

 

[UhClem]

I was wondering if anyone has done this before in rocketry.

You should be asking Google: https://aeroconsystems.com/tips/dahlquist_resistor_igniter/dahlquist_igniter1.htm

 

[Tonimus]

You should be asking Google: https://aeroconsystems.com/tips/dahlquist_resistor_igniter/dahlquist_igniter1.htm

That's actually how I figured out what my igniters were. They were in a batch of stuff I bought, and labeled DCR (what I assume meand Dahlquist Carbon Resistor) Igniters.

 

[sghioto]

Resistor igniters work fine for rocketry. I use 10 ohm 1/8th watt carbon film resistors on a 12 volt system. The resistor is basically the bridge wire and you can ignite APCP directly with them if you have good contact. Normally I dipped them in an epoxy pyrogen.

https://www.digikey.com/product-det...ronics-inc/CF18JT10R0/CF18JT10R0CT-ND/2022697

Steve G

 

[tfish]

You should be asking Google: https://aeroconsystems.com/tips/dahlquist_resistor_igniter/dahlquist_igniter1.htm

David, I'm guessing this would still be regulated just because of it's "final intended function" even though it contains no chemicals per say?

Tony

 

[UhClem]

David, I'm guessing this would still be regulated just because of it's "final intended function" even though it contains no chemicals per say?

Impossible to say since the ATF will not provide the criteria they use to decide. All you can do is ask them for an opinion on a particular device.

The evidence suggests that so long as you do not use anything that appears on the list of explosives, you are fine.

 

[Astronot]

You should be asking Google: https://aeroconsystems.com/tips/dahlquist_resistor_igniter/dahlquist_igniter1.htm

Thanks for the link. Some very interesting info there. This jumped off the page at me right away. Pretty cool.

With appropriate ignition system design, 25 Joules can easily be transferred from a compact, hand-held firing box to a pair of resistor initiators half a mile away. A single resistor initiator can be fired two miles away, using #18 AWG zip cord firing leads. No relay box is required.

Reliability is extremely high as well.

David