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Basic stamp board witstanded direct 12kV hit, but it seems to be affected by EMP ? — Parallax Forums

Basic stamp board witstanded direct 12kV hit, but it seems to be affected by EMP ?

CuriousOneCuriousOne Posts: 931
edited 2013-09-06 10:46 in BASIC Stamp
A quite strange and weird situation.

I'm building a high power strobe flasher, which is being controlled by basic stamp 2 board. Nothing sophisticated - voltage tripler and stabilization board, 2000uf 600v capacitor, trigger coil and strobe lamp. Basic stamp, according to keypresses, output pulses of various duration, via PULSOUT statement. The circuit as follows: Basic stamp 2 output, via 470 ohm resistor, connected to FOD817 optocoupler. The FOD817 transistor itself triggers the scr, which discharges 0.1uf capacitor into transformer, which outputs 12kV pulse for ignition. The basic stamp and strobe circuit use galvanically isolated power supplies for safety.

Initial tests were conducted with old minolta 4000AF flash, which worked just fine. However, when I scale things up, (connect FOD817 output to the more powerful circuit), it all messes up. The flash gets triggered only once, and basic stamp module hangs. Have to cycle power to make it work again. I suspect, the EMP created with strobe discharge, causes the problem? for obivous reasons, both circuts are about 10 inches away from each other.

Funny to note, that accidentially, the 12kV output from transformer slipped off, and was discharging into bs2 module GND pin, but module still works fine!

Comments

  • GenetixGenetix Posts: 1,754
    edited 2013-08-30 13:47
    Do you have filtering and decoupling capacitors on the BS2?
  • davejamesdavejames Posts: 4,047
    edited 2013-08-30 15:19
    CuriousOne wrote: »
    The flash gets triggered only once, and basic stamp module hangs. Have to cycle power to make it work again.

    Have a 'scope handy? Monitor the BS2's reset pin for glitches.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2013-09-06 10:46
    EMI is a problem for most microcontrollers. You definitely need a Faraday cage or a shielded enclosure for the BASIC Stamp Module. Even with that, control wires can act as an antenna and deliver EMI spikes back to the module. Whenever a high-energy system emits EMI in a pulse fashion like this you will need to employ considerations for such a system.
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