Joined: Aug 13, 2008 Posts: 93 Location: Bloomfield Twp., Michigan
Posted: Sat Sep 21, 2019 3:11 pm Post subject: How to connect a 12 V tach.
Just as an aside, is there an easy way to wire up a 12 vdc tach or should I look for a 24volt model. If so, who sells them? Understand that most of what was written above went zoom! right over my noggin!
Quote:
Your post was actually hijacking Lyle's post and not at all related to mechanical tachs. I took the liberty of starting a thread for you here. Wes K. management
As a rule electric tach's used with Pulse type ignition are the 3 wire type.
1 - Positive power wire is + system voltage. IE 6, 12 or 24V.
2 - Negative - ground wire grounds the tach to the vehicle.
3 - Brown sense wire senses the pulses at the coil negative - terminal.
A 12 volt electrical tach requires no more than 12-14 V's on it's + positive wire. So you could either place an inline resistor in whatever source wire you decide to power the tach to drop the voltage from 24-28 to 12-14. Or you could run a special wire from the 1st battery (on the M38 this is the under hood battery) to the + positive line on the tach. In either case that power source must be switchable on/off so as not to run the battery down when the engine isn't running. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
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