Hi.. I need a vintage look tach but can't find a 6v negative earth tach anywhere. This is the style I need but I pinged their tech guys to see if it can be run on a 12v supply but get 6v from the coil lead but they said no. I am not so sure. As an option i was thinking of running an optocoupler to trigger the 12v Tach from the 6V coil connection Anyone successfully run a 12v Tach on a 6 volt car?
Almost ten years ago, I sddressed this subject : https://www.jalopyjournal.com/forum...tachometer-on-6-volt-positive-ground.1066826/. I found we could, but in the end, it turned out to be economically unfeasible, so I wrapped it up after producing 20 units. All is not lost, however. Lately, several decent looking 6 volt tachometers have appeared on the market. The entries from Bosch and Mooneyes are particularly appealing. https://www.ebay.com/itm/196520316175?_skw=6+volt+tachometer&itmmeta=01K9HRJBKM3MW88XF2QDP7BY19&hash=item2dc1860d0f:gpIAAOSwhl1mVklW&itmprp=enc:AQAKAAAA8FkggFvd1GGDu0w3yXCmi1enQMfi2MDScxf+SliuEs+Yoo61KXMTN9C50dxgW1Rgg6zrf6j3rNWm2TyCCuAo2wDhb1GD5pamYB5jNtQ865gQOIf73ostdYHQ2Fc7xd1zTSouk4152CcMy3VXzI2NBgOKrYyAsailzQEfz+DjP6G1Ui9j+6IthDuUiSCJYPWuqmAuRsHrnF2NdVd9icHdD7JmAneJj1wqgqNBFuwr8oEVYHuC9OlNokVKl5fiuVu495pa8NH3vCHlJCTvuqxj3dcQKnvMpJi7vOZGQzcWSlHrTWGMurufJkTqV+QMbzdI+w==|tkp:BFBMgLrJuMxm. https://www.ebay.com/itm/197230312509?_skw=6+volt+tachometer&epid=1734026430&itmmeta=01K9HRJBKMCVZE5S98FGRQQ6NG&hash=item2debd7bc3d:g:434AAOSwJg1jukpI&itmprp=enc:AQAKAAAA0FkggFvd1GGDu0w3yXCmi1cVIm3kfJ7kNo+kk6mtWaYOgl1PXxHonc4yJ7/07AbsUqt3yKEcmO/Knk8W8dISrzfSTB6MS1AkR4agQdJ5GDOrotZM6AaCAW4yHi4mHHtpZV8t105UIzzGU1bTnyKWUBiC6av5rlGhFYPPL3RV0JdgwpiJKmWHxieoZW6coVPvoWbIBkIAqTmv7veg9OG+qHQjEEMCru3XM0sjYuFlVnQIhM7OnjQWZ+Syv5u0qRLL13jhIcZTd4bBoF2Z19TnC9A=|tkp:Bk9SR4C6ybjMZg. I'm sure there are others. Oh yeah. Hey! @d2_willys ; you can probably drop your project now that these new units are available!
Thanks for the information. Its a shame that it didn't survive into a commercial product, the must be a market for it What i am trying to achieve is a pre-war look in from the era when all tachs were cable driven, but an electronic version. But the only 6v ones I could find are more modern looking, which is a bit self contradictory.
From the 'noise" on the various car forums at the time, I thought it would be a big hit. It seems like I saturated the market with the first 15. It took forever to sell the last five. I ended up selling the last 5 at my cost ($120.00). BTW, AFAIK, all 20 are still up and running strong.
After thinking about it, I have some information that may be helpful. When we developed out "Tach Driver", we found that we had to change the polarity and raise the voltage of BOTH the tach logic power AND the signal from he distributor. Since you are talking negative ground, you will only have to worry about voltage. Amazon has a whole plethora of devices that can do this and they are quite inexpensive. Perhaps a couple of those could serve your purpose. We also found that the modern tachometers are quite sensitive to the "dirty" power put out by generator systems. I think that if you got devices that ensured "clean" power, you may be able to pull this off.
I already had "dirty" power issues with a GPS speedo. The current drain is very small so I powered it by a seperate 12v rechargeable battery pack. Lasts about 6 months on a charge. I may do the same with the tach. So long as the 6v and 12v share the same ground it may work with the coil triggering the tach
From my experience, you have to bump the voltage of the tach signal to make this work, so maybe one booster on the signal will work. I would try it without first, as some of this new stuff is extremely tolerant. I would think that an occasional spike on the signal side wouldn't be critical. as on the logic side. I think the battery will work fine, as none of this stuff draws much power. I just have an aversion to using them in situations like this. I like everything to be self-sufficient. I think if anything, the ground may be a problem.
Another idea would be to get the Bosch tach in the link provided, and get it retrofitted with a more period looking face. You could maybe do it on your own, or send it to one of the specialty gauge suppliers to have it done.
Converting any car to 12 volts is so easy, I just don't see going through all the stuff required to run modern stuff on 6 volts. It's just not worth the time and trouble. Your results may vary.
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