Poor Man's Data Logging

[Bazzateer]

I can remember the big pound notes before they brought out the smaller versions, and the old pre-decimal pennies and sixpences. Not the white fivers though!

 

[candy red]

To be honest you guys have lost me with this thread pretty much understand the electrical components
But you’ve totally lost me when talking
10 shilling notes
Sixpences
White 5 pound notes
Pennies
How do you wire that lot together

 

[AliK]

This is a way simpler problem and you just need to stick an opto isolator, a couple of diodes and resisters on the tach signal. It will pick up the pulses from the coil that would release the magic smoke from an arduino and output a nice safe 5V/3.3V pulse to the arduino. Then its just a bit of code to turn the pulses into a digital rpm output for your excel sheet.
Probably about £1 in parts!

I dont know tons about it but an opto isolator is a Schmitt Trigger. You wont need to mess about with anything massively complicated to iron out the spikes other than the conditioning achieved with the resistors.

Never tried it though so if you invest in all the parts to test it and it doesn't work I'm afraid you have lost an entire pound note!

Thanks Russ, as ever, good advice! I think you’re right, a bit of signal conditioning and a couple of diodes would do the trick. I was thinking the hysteresis of a Schmitt would clean up the secondary “bounce” pulses. I guess with a large enough pot/resistor and a zenner you can “tune out” the secondaries. Good food for thought. Thank you.

 

[Russell]

Thanks Russ, as ever, good advice! I think you’re right, a bit of signal conditioning and a couple of diodes would do the trick. I was thinking the hysteresis of a Schmitt would clean up the secondary “bounce” pulses. I guess with a large enough pot/resistor and a zenner you can “tune out” the secondaries. Good food for thought. Thank you.

I have just ordered an opto isolator. Never played with one before but my speedo needs one to pick up the signal from the handbrake switch to update the ODO into EEPROM.

I would quite like to build a data logger for mine but there is really no point as im using the factory ECU and will be looking at an AFR reading all the time. Once I migrate to a standalone ECU it would be more valuable but considering building a Speeduino for it at which point everything is logged anyway!

A friend of mine is building a Zetec turbo for his MK1 Escort and I am putting a Speeduino and wiring together for that in exchange for some fabrication work on my Z which means I will have it on the road sooner than I was expecting.