hobieboy wrote:My own update - wouldn't call it complete success yet but I finally was able to fire up the engine This is for a 6 cylinder twin plugged waste spark set up using 6 VB921s to drive 6 coils.
One lesson I learnt in my case - the CPU doesn't have enough juice to drive 6 VB921s. I ended up using a line buffer before the VB921 and now all my coils seem to be charging (still needs to confirm my dwell with a scope).
Did one of those a few months back, (I hate porsche owners) was a little tricky to get sorted.
Could you give more details of how you solved this ? Wiring, components etc.
Petteri
hobieboy wrote:My own update - wouldn't call it complete success yet but I finally was able to fire up the engine This is for a 6 cylinder twin plugged waste spark set up using 6 VB921s to drive 6 coils.
One lesson I learnt in my case - the CPU doesn't have enough juice to drive 6 VB921s. I ended up using a line buffer before the VB921 and now all my coils seem to be charging (still needs to confirm my dwell with a scope).
Essentially, I added a 74HC125 where the VB921 supposed to go per MSnSe instructions. Then each output of the 74HC125 is used to drive a pair of VB921; using 330ohm bias resistor.
Thanks James for this idea!
I suspect I needed this because my VB921 are remotely mounted in a separate chassis. But at least I'm pretty confident that I won't be over draining the CPU. YMMV.
This is for a 6 cylinder twin plugged waste spark set up using 6 VB921s to drive 6 coils.
