Electronic Tach question
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Race Director
Joined: Apr 2011
Posts: 11,183
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From: North of Toronto - Ontario
Electronic Tach question
I received a pay-it-forward tach from another member (thanks again champs65 
) and as expected the tach board appears to be toast, needle doesn't home when 12v and gnd are supplied with no signal. That's ok cause it's not where I'm going anyway.
I took it apart and checked the actual meter part and each of the two windings seem to be intact, applying a 1v dc supply to each independently moves the needle to a specific point in the rotation.
Now from what I've understood based on a document I found at Autometer, this is an air-core gauge and the two windings work together (against?) creating the movement of the needle.
What I can't seem to find, and can't test since this tach board isn't working, is what kind of voltage level those coils would be working at. 12v? 5? ??? I don't really want to test by destruction to find out.
I've only got a single output supply so I'm going to mickey mouse up a voltage divider to change the ratio between the two windings (I'm also guessing to go past the 45 deg point the winding will have to go from + to - but I'll cross that bridge when I get a safe voltage to work at.
I know Willcox made their own boards so they would know what output they used, has anyone tested one ???
Thanks
M
) and as expected the tach board appears to be toast, needle doesn't home when 12v and gnd are supplied with no signal. That's ok cause it's not where I'm going anyway.I took it apart and checked the actual meter part and each of the two windings seem to be intact, applying a 1v dc supply to each independently moves the needle to a specific point in the rotation.
Now from what I've understood based on a document I found at Autometer, this is an air-core gauge and the two windings work together (against?) creating the movement of the needle.
What I can't seem to find, and can't test since this tach board isn't working, is what kind of voltage level those coils would be working at. 12v? 5? ??? I don't really want to test by destruction to find out.
I've only got a single output supply so I'm going to mickey mouse up a voltage divider to change the ratio between the two windings (I'm also guessing to go past the 45 deg point the winding will have to go from + to - but I'll cross that bridge when I get a safe voltage to work at.
I know Willcox made their own boards so they would know what output they used, has anyone tested one ???
Thanks
M
