A Hobbs meter can be wired to a normally-open oil pressure switch that closes at 4 PSI to start recording engine time once the engine is running.
A standard air-cooled VW low oil pressure idiot is activated by a normally-closed oil pressure switch that opens at 2.5 PSI to shut off the light when oil pressure comes up.
To avoid having to plug in three different things into the oil pressure port (the third being the pressure gauge sender) there must be a simple way to combine the functions of the Hobbs and idiot light senders. Perhaps a small SPDT relay that switches between the two circuits so running either the idiot light or the Hobbs meter but not both at the same time?
Suggestions welcome!
A standard air-cooled VW low oil pressure idiot is activated by a normally-closed oil pressure switch that opens at 2.5 PSI to shut off the light when oil pressure comes up.
To avoid having to plug in three different things into the oil pressure port (the third being the pressure gauge sender) there must be a simple way to combine the functions of the Hobbs and idiot light senders. Perhaps a small SPDT relay that switches between the two circuits so running either the idiot light or the Hobbs meter but not both at the same time?
Suggestions welcome!
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