We can and have engineered problems for every solution. I am somewhat new to high power rockets, and onboard electronics and energetics. I had a few assumptions with energetics and having some time at the range and research I am working on developing safe practices for my HPR projects.
I come from a background of working on cars, electrical diagnostics and making stuff go fast. I have some advanced electrical testing tools and will be using them to bench test my 2 altimeters that have both a "battery" terminal and "switch" terminals. I would never plan to or think to walk up to the inspection table with my rocket beeping away. I will use a multi meter Snap-on EEDM596D its very similar to Fluke meter, and I have a Snap-on Vantage Pro, a 2 channel oscilloscope. I will be testing a Missile works RRC3 and a ARTS2 with some home dipped ematches and a 9volt battery. I will twist the wires together for a switch and see what the meter shows.
I also tested how the multi meter actually performs a OHM check, if anyone uses a meter to check the continuity on your energetics it can be outputting a spike to 1.136 DC volts and leveling off at 0.607 DC volts as I measured here with my multimeter and scope. I understand there is no amps behind the ohm meter check but its still putting voltage through the energetic.
First up is the RRC3. I tried to come up with every possible testing scenario on a fully functional altimeter, not taking into account damage, false launch detect etc.
with out the ematches hooked up there was nothing present at the energetic terminals as measured across the apogee, drogue and aux +/-. after hooking up the ematch, and battery but no switch continuity (off) I measured 89mv from the ground terminal on the battery to the positive side of the 3 "+" terminals for energetics. I did a ohm check and positive battery terminal goes right to the one side of the switch terminal, then as it goes though a switch the battery power goes back into the other switch terminal and the altimeter turns on. I did a ohm check and the ground side of the energetic terminals pass through a solid state device, so the altimeter does a pull to ground to operate the energetic terminals. So as soon as the altimeter is powered on there is full battery voltage present at the "+" terminal and only a small amount of actual current going through the ematch for a continuity check by the altimeter. it seemed to be less voltage then the 0.607 dc volts I recorded with my meter.
I also tested my ARTS2 altimeter and had similar results. The terminals for apogee and main are not marked +/- on it but the mv measured with just the battery connected no switch was more on the far right terminal, about 110mv spike holding 2mv and became less as I moved to the left, same 110mv spike but holding 0.7mv. I think it is positive then negative from right to left for each energetic.
I was able to measure the continuity check from the ARTS2 for the energetics and it was 132.7mv.
I have read the thread and am waiting to hear on a few points. I get that the energetics need to be inhibited. does the switch terminal on my altimeters satisfy this? The voltage present is only in the order of mv and I presume very small amount of current, and this is only present checking from battery negative to energetic positive. if I check across the energetic terminals the voltage is 0 as it goes through a solid state switch, pull to ground, back to the battery. So if the solid state failed, and I powered the altimeter on then pop, the energetic would fire.
I will continue to research, look and learn how to operate onboard electronics and energetics in a safe manner. I will plan to use a reliable switch from battery to altimeters that do not have a switch terminal, and I will perform a physical brake in the energetic "+" lead that I can reconnect with the rocket on the rail but horizontal then activate the main switches to power on the altimeters controlling energetics. I will not be out at a prep area taking apart and re-assembling a rocket "under the gun".
~John