I would also add some zener or transzorb, and would be wary of the engine start-up transient. There are several high value inductors being disengaged abruptly that can send a mighty pulse back. Depending on the age and state of the battery that pulse could be dangerous.
On Tuesday, September 4, 2018 at 8:49:07 PM UTC-3, gregebert wrote: > > OK, schematic looks right now > > Large filter caps (> 100uF) by themselves wont solve the spike problem. > You will need some series inductance (try 100uH), and some lower-value caps > (0.1uF) in parallel because larger caps dont filter high-frequency noise > very well. Also be sure to have a series diode from the +12V automobile > power to protect against reverse-polarity. I recommend a fuse as well. As > far as what L & C values to use for the filter, the values I guessed at get > you a corner frequency of a few kHz. You might want to put a scope on your > car and see what noise you get during engine-idle while the battery is > charging; I'm guessing the alternator is the biggest source of > low-frequency noise, but it could also be the ignition system. I've never > looked; always been curious. > > Plan on noisy signals from your sensors; there's all sorts of electrical > noise under the hood. There's a lot of clever automotive engineers with > many years of experience who have solved this problem, and hopefully > published some technical papers. > > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/99d2c0fa-a9ed-4385-9c8e-ba81c5606eb2%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
