Bench test a Tach with a Battery Charger?
Has anyone ever bench tested a Tachometer with a battery charger as explained below:
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When hooked it up to a V-8 tach's input (+ve to tach +ve and -ve to gnd), it shows exactly 1800 rpm.
A 120 Vac 60 Hz battery charger puts out an imperfect DC voltage. It is actually a pulsating DC voltage that corresponds to
1800 rpm for an 8 cylinder,
2400 for a 6 cylinder
3600 for a 4 cylinder
I did this with my tach and although it lit up the needle never moved. Suggesting that it is kapput if the above test is valid. :doh: