| ??? 05/01/06 10:30 Read: times |
#115282 - I'm with you. Responding to: ???'s previous message |
Russell Bull said:
First up, the vehicle body is a pretty substantial conductor. If you're dropping large voltage across two farthest points on the chassis then you've go problems!
What level of ground noise are we talking about versus the signals involved? Most auto electronics I've seen do not use optos (Nissan did use opto sensors for ignition trigger - guess what fails?). If you've got low level signals, either amplify at the sending end or use differential signalling - this can mean just using a differential input using a ground wire and signal wire from the source unit. Ground noise should be cancelled out. All that, and these most substantial drops usually only occur during cranking. You really need to KNOW that you have ground injection issues. You are in a position to instrument one of your chassis, I'd use a TIG welder to inject significant currents, and then probe the chassis. Of course you could attempt to model it, but my method is more fun. Steve |
