Reply To: Testing coils, per1938 Bendix Scintilla procedure

[jeff-register]

Tom,

To replace the vibrater coil a guy can use a double pole double throw relay. It vibrates to the normally closed contacts till they are pulled down & become open & spring open closing the other contacts causing an open/close action. Only one problem the pulsing action is too fast, added a .20mfg capacitor to slow down the charge rate to a mechanical rate & worked well. Fixed many merctronic viberators that way. Tried  with 555 chips timer chips & no good, they ran into thermo runaway & cook ed. Never tried silicone switching chips , SCRs.Even sounded like the mechanical vibrator.

Buck,

When using a dual fire coil, the spark plug with the lesser amount of resistance will fire to ground & the second hi volt terminal has enough electrical energy to fire the second output. Happens  in a split second. Try less resistance on your test pins by making the gaps a little differances. then you are putting the test close to actual running app’s.