Greetings jholguin

In the interest of safety, one thing you may wish to consider is that MOSFETs very often fail short circuit. It may be worth including LEDs to monitor each firing circuit for voltage to avert an unintended ignition at the launch pad. I myself have be flying model rockets for 20+ years and witnessed a launch pad accident involving serious burns.
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trident

 

Boncuk, your killing me. I looked at your diagram and couldn't follow. Maybe it was just too late at night. Can you help by drawing in more of my schematic modified into your suggestions?

Trident, can you expand a little on this suggestion. Do you mean continuity?

 

Greetings jholguin
This is an example of one way to check if any of the channels have power, ie a shorted MOSFET, with an LED or better still use a low current buzzer.
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trident

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Hi trident9,

I guess the rockets will fire without continuity test. The circuit needs the "ARM" switch to be closed for current flow across the igniter.

A better way is paralleling a current limiting resistor with the arm switch (~100Ω) for the continuity test. To arm the circuit the resistor just has to be shorted by the switch.

So the switch has dual functions: TEST/ARM.

Here is a simple test circuit. The equivalent counter output must be known using one LED. Connecting one LED in series with the igniter the respective LED will light when the transistor is conducting.

Regards

Boncuk

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Proper Planning Prevents Piss Poor Performance

 

Hi jholguin,

in the meanwhile I worked out a circuit design with following features:

- manual or automatic (ripple fire) launch
- variable ripple speed from 0.5 to 5Hz
- LED controls for the rockets being fired and sequenced for continuity test
(32 LEDs total)
- continuity test either manually sequenced or automatic.
- manual firing only possible by pushing two buttons. (in case the ARM switch is activated and somebody pushes a button inadvertantly)
- ripple firing can be interrupted by disabling the timer circuit.
- debounce circuitry for the manua FIRE buttons

Continuity test is only valid for the nominal igniter resistance. Either interruptions or shorts are indicated as NO-GO by leaving one of a pair of LEDs unlit. The continuity test uses strobed comparators (LM311) for 100% reliability.

Board: Double sided, dimensions 6.65X6.915inches.

Regards

Boncuk

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__________________
Proper Planning Prevents Piss Poor Performance

 

I like the dual function switch.

 

hi
i also fly model rockets, and also found the need to use multiple launch pads, a while ago i designed a circuit that allows me to send 6 seperate signals down a 2 core cable.

if this is of any interest to you pmme and ill send it to you, i have since moved over to 2.4ghz launch setup of which im still ironing out a few issues.


where in the world are you?? and what do you fly???

im currently working with e,f,g engines.

 

Hi Johnny,

here is the screenshot of the operating panel.

The bottom row of LEDs indicate counter state (simultaneously firing), the top row indicates a valid continuity check of the corresponding "channel".

Those LEDs remain dark if the igniter is interrupted or shorted.

Boncuk

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__________________
Proper Planning Prevents Piss Poor Performance

 

See image attached...

 

Sorry didn't attach image on previous

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