12V/3s LiPo Starter for Model Rockets

A relatively simple starter for electric igniters for rocket motors. Since it is designed for 12V / a 3s Lipo (=11.1V), almost anything in the hobby area should be ignitable with it, and longer cable lengths can be used for safety

Functionality: The key switch acts as the main switch. When switched on, the volt/ammeter serves as a power-on confirmation and, of course, for reading voltage and current. The ARM switch activates the ignition channel and lights up as confirmation. The Cont./Launch button lights up when the channel is "armed" and the circuit is closed (i.e., when an igniter is connected)

The series-connected 4 Ohm resistor is optional, but in case of a short circuit, it limits the maximum current to 3A, which is also the limit of the switches. I am using a cable length of 12.5m between the igniter and the igniter device. 10m or 5m would probably also be sufficient. I used a 3s 2.2Ah Lipo from Hobbyking that I still had lying around. It has dimensions of 110x30x30. A few millimeters more are okay. I also had screws, insert nuts, and cables for soldering the internal wiring lying around. Feel free to use the ignition cable for the internal wiring as well

The circuit diagram is with the pictures; soldering is required! Pay attention to the polarity, especially with LEDs and the toggle switch!

Additional material (Amazon Affiliate Links) :

Key switch 3A: https://amzn.to/41JgC50

5 Ohm, 50W resistor for current limiting: https://amzn.to/4peJpbs

Safety toggle switch, green illuminated: https://amzn.to/4ge6FSW  (2x needed with addon)

Push button, blue illuminated: https://amzn.to/3HPAVac

Volt/Ammeter: https://amzn.to/3VcJ5wh

XT60 plugs and sockets for battery and addon: https://amzn.to/4m5uBcr

3s Lipo (as an example): https://amzn.to/4m8xjhu

some M3x12 screws, e.g., these: https://amzn.to/3Ij3GMt

some brass insert nuts M3x6x4.5, e.g., these: https://amzn.to/3V6D1p4

XT30 plugs and sockets for connecting the cables: https://amzn.to/4m8xYzu

25m twin lead 0.75mm², halved for a total of two 12.5m ignition cables: https://amzn.to/3I4EXLU

Crocodile clips for soldering in black and red, sufficient for five ignition cables: https://amzn.to/4ge7Vp8

And, oh yes, of course, the box. I didn't want to reinvent the wheel here, especially since some time ago I found the parametric boxes (with OpenScad code 😍) by Iceman. I'm also uploading a remix of it here in the right size with mounting options.

For this, 6 M3x25 screws or grub screws are still needed per box, e.g., these: https://amzn.to/3JUpApW

And for those wondering what the connection labeled "Addon" is for: I'm planning another box where an additional 5 channels can be ignited. It's essentially already finished; I just need to make it look nice. It will probably be available by the end of the week

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