Anyone have a schematic diagram for the Bosch Ignition Control Module?

dllubin said:
Yes. I am guessing that there is an amplifier/comparator function in there that switches the power device. Do your photos show enough detail that I could pull a schematic off them?
Click to expand...

I haven't taken one (of the Volvo module) apart - if you can't locate the info you need I'll gut one & take pics of the circuit board.
 
I managed to find a schematic of the Motorola version of the HEI module. The reluctor output sees an input impedance of about 10K. That pretty much tells me what I need to know.
 
dllubin said:
I'm in the process of designing an interface between the Bosch distributor and a capacitive discharge unit that was designed for points. Does anyone have a schematic diagram for the Bosch Ignition Control Module? I'd like to see how Bosch does the interface to the reluctor coil.

Thanks,


Don
Click to expand...

Hi Don,

you could use the following circuit (copied from an Australian electronics magazine) to convert the hall effect signal into a 5V TTL signal:

Snap 2019-09-17 at 18.47.50.png


You then need something to drive your capacitive discharge unit, e.g. an IGBT like in the following circuit:

upload_2019-9-19_17-55-7.png

This is obviously designed to drive the coil directly, but you get the idea.

Note that ignition drivers typically feature some form of adaptive dwell control as well (which I'm not sure that your capacitive system would have). A good article about this can be found here:

As per the second article, I'd recommend looking at the BIM 137 on the output stage.

Cheers,
Dom.
 
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dcioccarelli said:
Hi Don,

you could use the following circuit (copied from an Australian electronics magazine) to convert the hall effect signal into a 5V TTL signal:

View attachment 25526

You then need something to drive your capacitive discharge unit, e.g. an IGBT like in the following circuit:

View attachment 25525
This is obviously designed to drive the coil directly, but you get the idea.

Note that ignition drivers typically feature some form of adaptive dwell control as well (which I'm not sure that your capacitive system would have). A good article about this can be found here:

As per the second article, I'd recommend looking at the BIM 137 on the output stage.

Cheers,
Dom.
Click to expand...
Dom:

My interface will look similar to the first schematic. The input to the capacitive discharge unit is a relatively high impedance so there is no need for a power device. It is basically a 25 ohm resistor designed to keep enough current through the points to keep them clean. I can probably get rid of it when using a reluctor pickup.

Those two articles are quite interesting. That is the first reference I've read about the Bosch HEI module. Sounds a bit more sophisticated than the old GM module that people use. I will not need to worry about dwell control as that is important only for Kettering (inductive) systems. It is good to see that these modules can dynamically adjust dwell to optimize coil primary current.

Thanks,

Don
 
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