justin_o_guy2 wrote on 04/06/17 at 17:56:35:He's more concerned about the reverse EMF when the coil drops.
Put another diode in parallel?
Put a 16 volt Zener in parallel?
The Zener is a good idea for suppressing the spike when the coils are denenergized. The solenoid coil can potentially generate a few hundred volts from inductive kickback. Add another coil and you can potentially double this as the voltage from the simultaneously de-energized coils will add together. Let's assume we get a kickback of 214 volts form a single coil. With two it would be up to 428V. If the original Suzuki diode has a PIV of 400V then I'll be SOL once it gets hit with the higher kickback and need to order a new diode from Suzuki. Or substitute in one with a much higher PIV.
Any zener used would have to have a high enough PIV too if one was used.
And that's where it gets complicated - knowing how high of a PIV I'll need is a PITA. I can try many different diodes with sequentially higher PIV's until I find one that doesn't pop. Or I can get empirical amd drag the oscilloscope out to the bike to make some accurate measurements of the event. I've had to do this before for work a long time ago, measure the peak inrush current of hybrid switch mode power supplies. Capturing such short lived transients is tough to do. It can be done but it's alot more work than I want to deal with right now.
I want to have fun tinkering, not start an elaborate experiement where I have to use my noodle. And I'm not sure I have the correct resistor on hand for such a test anyways. Has to be like 0.1 Ohms 50 or more Watts with 0.1% tolerance.
You put the resistor in series with the circuit you're measuring and place the oscilloscope probe to measure across that resistor, then very carefully set the trigger for the expected time interval and sync the trace to that trigger. Now you need to observe the trace at different volt/div settings until you find correct voltage range. Finally, make the event happen several dozen times and record the measured voltage each time and make an average of the recorded values. Now you know how big your transient gets in terms of voltage after mathematically deriving the voltage from the measured current and the known value of the test resistor.
All of this completely bores me to tears so I'll just grab some alligator clips and wire cutters and see what I can see brute force style.