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photo sensor ignition

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tomcer34:
hi, I want to replace hall sensor from my ignition to for some photo sensor. Can u suggest me some fast one? More then 30kHz. Reason for replacing hall sensor it´s because it´s too slow for me.
Thank u for help!

Benta:
A one-cylinder 2-stroke engine rotating at over 1.000.000 rpm? Or a 12-cylinder rotating at over 80.000 rpm?
 :scared:

CaptDon:
We use hall effect sensors in turbochargers giving 8 pulses per revolution and the turbos run at a max of 28,000 rpm. Our sensors don't lag at all. Why do you feel your sensors aren't fast enough? Probably the crappy circuit surrounding your sensor maybe? We run dynamic compression on the incoming signal to keep it leveled in amplitude then hit a high gain limiter/clipping stage to form a square wave whose leading edge remains relatively accurate in phase relationship to the 8 teeth on the shaft. This whole mess is used with a pair of X/Y accelerometers to accomplish precision balancing of turbocharger compressors and turbines. It is real cool when 50 pounds of 28,000 rpm rotating mass comes apart!!! I've seen the pieces go through 1/4" steel plate! 8 pulses per revolution at 28,000 rpm is still only 3740 hertz. Why in the world do you need resolution at 30Khz??

Terry Bites:
Rise times are in the uS or nS for hall sensors. How many Mhz do you need?

floobydust:
Optical switches do not do well in vehicle/automotive applications- if the dirt doesn't contaminate them, the heat or moisture does.
You are very hard pressed to find slotted optical switches that are AEC-Q102 qualified. I think they aren't reliable- can't seal them due to moving parts, temperature cycles or the heat are very harsh and CTR degrades as they rapid age.
Chevy 90's LT1 Optispark was a flop for all the reasons I've listed.

I notice more automotive racing distributors are using optical pickups, which surprises me but there is much less sensitivity to EMI.
Most are primitive 8-slot like Mallory Unilite, using 5mm LED/photo-transistor.
The MSD (pic) looks totally overboard with what 1,024 slot wheel? Silly because the slop in timing chain and distributor gears makes that pointless (pun intended).

A crankshaft 60-tooth pickup is fine. Unless a one or two cylinder engine, because they have huge variations in crank velocity an ECU can make timing errors generating the next spark or fuel injection event. A V-twin is terrible, the crank slows down during a compression stroke, speeds up after ignition, but a misfire can happen and the 45° firing interval Harley riders love makes it rough to follow to estimate spark timing.

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