Second optoisolator on MS2
#43
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I'm going to try the 2nd optoisolator and I am ordering the parts now. Please make sure these parts number are appropriate for my needs:
Index Quantity Part Number Description Customer Reference Available Quantity Backorder Quantity Unit Price Extended Price
1 2 4N25VS-ND OPTOCOUPLER PHOTOTRANS 20% 6DIP 2
Immediate 0 0.57000 $1.14
2 5 470QBK-ND RES 470 OHM 1/4W 5% CARBON FILM 5
Immediate 0 0.10000 $0.50
3 5 4.7KQBK-ND RES 4.7K OHM 1/4W 5% CARBON FILM 5
Immediate 0 0.10000 $0.50
4 5 1.0KQBK-ND RES 1.0K OHM 1/4W 5% CARBON FILM 5
Immediate 0 0.10000 $0.50
I also need the 0.01 uF Capacitor, what is a good digikey part number for this?
I'm ordering some extras as I may also do this for a friend that is having the same issues with his MS1.
Index Quantity Part Number Description Customer Reference Available Quantity Backorder Quantity Unit Price Extended Price
1 2 4N25VS-ND OPTOCOUPLER PHOTOTRANS 20% 6DIP 2
Immediate 0 0.57000 $1.14
2 5 470QBK-ND RES 470 OHM 1/4W 5% CARBON FILM 5
Immediate 0 0.10000 $0.50
3 5 4.7KQBK-ND RES 4.7K OHM 1/4W 5% CARBON FILM 5
Immediate 0 0.10000 $0.50
4 5 1.0KQBK-ND RES 1.0K OHM 1/4W 5% CARBON FILM 5
Immediate 0 0.10000 $0.50
I also need the 0.01 uF Capacitor, what is a good digikey part number for this?
I'm ordering some extras as I may also do this for a friend that is having the same issues with his MS1.
#49
Boost Pope
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The traditional circuit, with a pullup on JS8 and nothing else, has virtually no noise immunity and zero hysteresis. In other words, it's extremely sensitive to every form of noise and distortion imaginable.
The opto converts the circuit from being a voltage-mode device to a current-mode device. This grants it some immunity from induced noise. (eg: voltages induced into the long wire between the ECU and the sensor have relatively little effect on this topology.)
And, to the extent that optoisolators do have a miniscule amount of hysteresis, that also helps.
The opto converts the circuit from being a voltage-mode device to a current-mode device. This grants it some immunity from induced noise. (eg: voltages induced into the long wire between the ECU and the sensor have relatively little effect on this topology.)
And, to the extent that optoisolators do have a miniscule amount of hysteresis, that also helps.
#50
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OK so after I did the second optoisolator I didn't touch the timing which I had set prior. I went to check the timing tonight as it seems to be running sluggish, I set the timing in megasquirt to fixed at 10 degrees and couldn't find the mark. Well as I looked around the pulley I found it on the alternator side as show in the picture. Before I did the 2nd optoisolator I set the timing at 10 degrees and it worked fine. it now looks like I'm 180 degrees out If I put my timing light on the 2nd plug the mark shows up on the opposite side closer to where I want it to be. How is this even running?
#55
https://www.miataturbo.net/ecus-tuni...-sensor-71726/
10 nF worked well.
0.1 uF would produce a delay of around 100 us, (4° at 7000 RPM) which would vary if the input trigger thresholds of the CDxxxx IC varied, like due to temperature.
BTW one thing the opto-isolator circuit does, is be slow and not respond to very thin spikes of noise.
#56
With a .1uF cap, the ECU wouldn't even sync since the RC constant was so high.
As for the 40106 discussion, it's an excellent trigger due to it's delay (lack thereof) and hysteresis. I think for 10V, it has about 3.5V of Hysteresis, and the response time is sub-100ns.
Glad the optoisolator worked.
As for the 40106 discussion, it's an excellent trigger due to it's delay (lack thereof) and hysteresis. I think for 10V, it has about 3.5V of Hysteresis, and the response time is sub-100ns.
Glad the optoisolator worked.
#57
Boost Pope
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Although it's nice to be able to converse with people who actually understand the concept of an RC filter and how it applies to the real world.