I'm going on two years with the 1.5v energisers in mine. Haven't taken them out since first install. Tach reads within a few rpm of my Sun dwell tach and within a hundred of my Peerless dwell/tach. I'm not going to mess with it till it quits working.
<cite>www.techlib.com/electronicsmercury.htm The link shown gives an alternate battery cricuit that will work in the old tach transmitters. </cite>
Guys, a simple fix is to power this circuit from your vehicle----then hook the output of this circuit to the output of the batteries on the transmitter.http://www.re uk.co.uk/OtherImages/zener-diode-voltage-regulator.gif the values are: car voltage input R1=151 ohm, 1 watt resister ZD= 2.7 volt zener diode, 250-500mw (current capacity) this circuit can completely eliminate the batteries, just run vehicle power inconspicuously to the transmitter. this can be built on a 1/2" x 1/2" sq. pc of perf board. the resistor and zener diode can be easily obtained from an electronics parts store. ------------this is what Im going to do to mine very soon---------
I will do that soon. Im not having luck with links tonite. For now, the circuit is very simple, two parts. It is a very simple battery eliminator (thats all it does). It does not refine the outdated electronics of the transmitter. I will try to draw up the circuit and show where to hook it to the transmitter.
....simple fix is to power this circuit from your vehicle----then hook the output of this circuit to the output of the batteries on the transmitter. the values are: car voltage input R1=151 ohm, 1 watt resister ZD= 2.7 volt zener diode, 250-500mw (current capacity) this circuit can completely eliminate the batteries, just run vehicle power inconspicuously to the transmitter. this can be built on a 1/2" x 1/2" sq. pc of perf board. the resistor and zener diode can be easily obtained from an electronics parts store. ____________________________________________________________________________ There was an errant space confusing everything. Got the pic to work. Tim D.
Thanks guys--------I appreciate the help thats what happens when you type instead of cut and paste!!!!!!! Im doing some breadboarding work this weekend----the simple circuit should be all thats needed------but we all know what "should" really means!!!!!!! Im still concerned about the power rating required to make it foolproof. Ill post more when I know it.
Great post guy's. I have no clue what all this means. Can someone make it simple for some of us gray hairs. Please.........Gonna go look for my teeth now.
I have been scouring the internet, reading posts here etc. This is my take on the situation..... -Originally they use 1.35v mercury batteries that are now banned -The concerning issue is length of battery life and a linear voltage drop So, my question is why not just go to the lithium or alkaline batteries and just change them more often and periodically check them against a second tach to verify that they are allowing to stay in range? Seems like the easiest option. I find it funny that so many here have wired a "converter", "reducer", etc. Yet with every story there is some sort of a caviate. Not only that, but there are many posts that say they did it and so far not a single picture that shows their setup. I wouldn't think that something like this would be that tough for an electrical engineer. V=IR is still relevant, right?
My earlier post still holds true. I'm going on 5 years with the same AA batteries in my '47. I even got lazy and haven't taken them out the last two winters and the tach is still working fine.
After 5 years is it still acurate? Have you checked it's accuracy? That is my main concern, I am installing a sending unit for a magneto for actual race use on a gasser. Just making the needle move doesn't do much for me, I want it to function properly so I don't blow something up.
I have checked it and it was accurate but like I said in my original post I wouldn't rely on it to be dead on with something I was really gonna run hard I would have it converted. For the most part it is accurate but it does have the needle bounce a little especially when decelerating.
About 6 or 8 years ago I found and bought an NOS sun tach and sending box that was 6cyl 12v. It was mint and in the original box. It worked great for about 2 years but then became irratic. So I replaced the battery with the correct battery. It worked for about another year or so but then became irratic again. During that time I installed an MSD box. Could this have hurt the tach or is it just a battery issue again? I was just going to send it to William's but I haven't gotten around to it. I haven't driven the truck much lately(read I got married and had children...lol)
Old post, but I use AA rechargables in mine. 2.6 V. Been going on 4 years now and never recharged. It reads within 20 Rpm of my Sun analyzer tach. All the electronics conversions aren't really needed unless someone left the old leaking batteries in it years ago.
Some have the battery soldered in. Does that mean that they are recharged by the unit? In which case why would you need a battery anyway. Guess I answered my own question.
No. The soldered in batteries needed replaced ocassionally like the others. A friend had one of those and he added a remote aa batt box under the dash and wired it to the transmitter batt wires. If yours still has the soldered batts in it, it would make more sense to convert it than to repair it.
Here is another option I have also used that would work with a full or half sweep tach. My 47 I still have the AA batteries but I did this one for my Mustang: http://www.jalopyjournal.com/forum/showthread.php?t=297171
The batteries that were in mine were not soldered. Something that I did not see mentioned was about running off the car battery with a voltage reducer. Every converter I have seen is using regular flashlight type batteries to get the proper voltage. I can easily build a reducer that can be put anywhere and tied into the box with out seeing it. What kind of a problem could that cause if any? If the car sat for several weeks I would think it wouldn't drain the battery if people are gong years on regular AA batteries. I have not tried mine yet, so I don't know if it ever works. For me it wouldn't feel right running it converted. The appeal for me is that you are using something old, and it works.
The Sun Tach I'm running in my Comet has been converted by Williamsons, there is nothing visibly different about it. It works great and no one would know the difference unless you tell them.
I'ts been a couple of years, I think it was about $200 but I'm not positive. I think it took about 2 1/2 weeks. Williamson's Instrument Service
We have boards that are very near completion. We Jumped the gun and advertised them a while back and found some problems when testing them under real circumstances, so we kinda dropped off the market, but they now seem to be working. We would still like a little more time to really test them out before we start taking money for them. They wire up just as a normal box would. No extra wires. They do not use batteries at all. They draw thier power from the ignition system, but not during the ignition event, so it will not affect power, or driveability. We have a Magneto version on paper, but it will require batteries or a 5th wire, because the way they work leave no power to be borrowed. The regualr boards work on 4,6,8 or 12 cyl and can be switched by the user. They require gutting your old stuff, and soldering a wire to each of the terminals inside. No permanent changes are done to the box, and from the outside it looks absolutely stock. Once we feel like they are really reliable, we'll put them up for sale. They will be $75.
>>>>>,I have two sets of these i'm not gonna use ,,one transmitter is 12V 8 Cyl,,the other is 12V 6 Cyl ,,the Mercury Batteries were removed before storage 50 years ago ,,so no mercury leakage damage ,,both Tachs are one green line ,...other blue line,,, both 9K as in the pic,,
>>>>>,I have several more old school Sun Super Tachs ( not Sun Super Tach II's ,,which are junk )),,,most don't require a transmitter ,,some are points only ,( but can be converted to HEI ) and a few that werk with HEI ,,
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