Timing Light

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longracing
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Timing Light

Post by longracing »

Came up with this idea while I couldn't sleep last night. Maybe someone thought of it before.

Using a transistor, resistor, wire and a bright white 5mm LED make a small permanent housing to mount it near your timing marks (maybe switch operated). Triggered from the #1 ignition signal. With a small shroud so it only casts light on the timing marks & fly wheel.

Might need a touch more circuitry to keep the strobe duration short enough but for only a couple of dollars could be worth while.
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jharvey
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Re: Timing Light

Post by jharvey »

Awesome thought, I've had similar. I seem to recall we have pushed that feature off and into freeEMS 2.0. Right now we are focusing on the bare min. Get it going, then make it fancy.

Keep up the thinking.
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longracing
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Re: Timing Light

Post by longracing »

I didn't think it needed any extra circuitry (unless you need to shorten/lengthen the pulse),
you already have an output for the #1 ignition.
Brian
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Re: Timing Light

Post by Brian »

It should work, LED's will take a lot higher current than they are rated for, if it is a short pulse current. For accuracy you need a very short pulse, much smaller than the dwell time, otherwise what you see is blurred. At idle, say 1000 rpm, a 1mS pulse spans 6 degrees so it needs to be a real short bright pulse.There was a circuit published in Silicon chip magazine in the reader contributions section some years ago, I have it here somewhere. A possibly better solution is just run a 555 timer triggered by the ignition event and drive a tranny or mosfet to control the LED/LED's. Then you can experiment with drive current and LED "on" time to get the visibility right. I have done it on a bench rig with black wheel and white timing marks, was pretty reasonable, using the ignition output signal with a very short dwell (much shorter than what would run an engine). The LED's get brighter and cheaper as the months/years roll on which makes it easier. www.besthongkong.com are pretty cheap and reliable for LED's, maybe there are better sources now, I haven't been in the market for a while.
davebmw
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Re: Timing Light

Post by davebmw »

I used this on my MS2, works well connected in parallel with COP number 1 just a very bright white LED with a 330R resistor in series with a 10uF cap paralleled up with 1K. it just catches the rising edge and shows the timing mark perfectly.
As for improving it you could setup the 555 as a monostable and have full control over the duration of pulse and really drive the LED/s to get a strobe visible in all weather conditions.
That would be childs play to incorporate into the PCB and would be a very handy setup tool.
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