Replacing a Hall effect sensor with an optical one?

[solver]

Is that possible? Since certain Hall effect IC's are hard to find on some countries, including Finland.

I'm aware of, that such replacement requires modification to an existing circuit(s). Not knowing too much of electronics theory side, is that feasible anyway, using an LED, or maybe a laser beam, and an optical sensor?

For those, who might wonder, I'm talking about 5bears' ignition circuits http://www.5bears.com/tim4.htm.

 

[TarheelTom]

I'm not familiar with 5bears ignition circuits, but I do have a small side business replacing hall effect sensors.

The sensor I use, is the Honeywell 2AV54, available from http://www.newark.com/, as pn 96F1986, currently about $19 US, plus shipping.

This may, or may not, be the same sensor you need. It's a sensor used by the ton by Bosch in automotive and motorcycle ignition system. As Bosch uses it all over the world, I would believe it would be commonly available in many countries, and able to be shipped to almost any country.

Tom

 

[John Rudd]

Is that possible? Since certain Hall effect IC's are hard to find on some countries, including Finland.

I'm aware of, that such replacement requires modification to an existing circuit(s). Not knowing too much of electronics theory side, is that feasible anyway, using an LED, or maybe a laser beam, and an optical sensor?

Yes its feasible, but bear in mind that you need to arrange some mechanical means of interrupting the beam to generate the pulses......
You could use a slotted opto coupler as the emitter and receiver..

 

[solver]

Thanks for the replies .

Yes its feasible, but bear in mind that you need to arrange some mechanical means of interrupting the beam to generate the pulses......
You could use a slotted opto coupler as the emitter and receiver..

You are right, the beam needs to be interrupted at precise moment, to provide proper timing for the spark.

But it needs more than an optocoupler, I assume.

I have done some raw testings on optotransistor/LED - pair, without any other parts, than ignition coil, but that optotransistor just has too much resistance, while the LED is off/interrupted on. So it can't 'emulate' the ordinary mechanical breaker points.

 

[solver]

Tom, I did some searching, and that Honeywell 2AV54 is available here also .

When looking its datasheet, it seems to have 3 pins, as HAL506UA(part used on 5bears schematic) does.

 

[TarheelTom]

On the ones I'm using, one wire is ground, one wire is hot (in our case, about +12 v), and the third wire is the switched leg.

Here is a pdf of the repair procedure I'm using, more or less.

http://tomwade.me/motorcycles/technical/oilhead_hall_sensors.pdf

Page 4 has a drawing of the steel ring with a slot cut through it which does the ignition timing.

This particular unit just creates a signal to the ignition computer identifying tdc. The computer uses that to determine rpm, crankshaft position, etc., then the computer decides when to fire the plug(s). Probably a bit too complicated for a model engine, but don't see why the HES couldn't be used to tell the ignition when exactly to fire.

Tom

 

[Blogwitch]

Solver,

One of the main problems of using an optical device rather than a Hall magnetic sensor is that on the small engines we build, they tend to get rather dirty whilst running.

With an optical device, the slightest oil film can stop it working, whereas with the Hall, as I found out on my own engines, they will work just as well when covered with oil.

Just another thing you might have to consider.


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