A while back there were some threads about converting the old battery transmitters to solid state. I've searched the archives and haven't come up with any solid info on how to do it. Has anybody done it? Got list of parts/diagrams etc.? I know about Williamson's, but I'd like to know what it takes for the DIY'er to do it. I'd like specifics, not theories, from somebody who's done it.
I'll bump this... Anyone have insite for tech week? I just got an EB-14 (12v 4cyl) transmitter, and I don't see the old square type battery. I'm sure it has to have one. Anyone have pictures of a converted transmitter guts, or advice here? Hey! Even Ryan was asking about it back in october!!!
The battery recommended in prior posts a Duracell PC12-A is no longer available, I have made lots of calls looking. No one has any suggestions on what to do except send the Tach to Williamson's. Someone on the HAMB must be able to come up with a solution for converting one at home.
I had a transformer made. The power from the wiring system goes in, and 2.7 volts comes out, no matter what goes in. It sits as a stand alone unit, with the wires exiting from the rear, so I can run the wires inside the car, hidden from view. As you're aware a car's voltage system runs between 10 and 14 volts. I had it made a few years ago, by the local T.V. repair place. Unfortunately thay are no longer in the area, and I don't know where they now are. I'm no electronics guy, so I dunno how they did it. i'll have to ask a friend who knows these sorts of thing to draw a diagram of it.
Anybody know the original volts of the old battery? Mine appears to have had terminals for 2 batteries the same physical size of an AA. A friend that ran a speed shop years ago said they were Two 1.7 volt batts, in series for a total of 3.4v. He said he started using old fashioned hearing aid batteries when the original ones went obsolete, but those are obsolete now too. So I found a 3.8v? miniture electronic surplus "integrated component regulator" on ebay and put it in. It worked fine for 6 months and then got erratic, then would stick, then died. I have read somewhere that a complete repro "guts" with a face & needle ( for the chrome head unit ) is available, and then just run the box as a dummy. Those guts were the same as the optional in-dash tach for 60-66 chevy pickups & big trucks. ( the 60-63 used the transmitter box, but the 64-66 did not need the box)
according to Williamsons website and Street Rodder, they contained mercury 1.35 volt batteries. Two would be 2.7V. I can see why your 3.8v only worked for 6 months. Thing is, my Eb-14 transmitter (12V 4 cyl) looks like it only has one battery. Don't know why though. Maybe because half the cylinders are missing on my motor...
Here's some info on a 2.5v IC regulator: I'll try to put up a link to a pic later to show it, it's smaller than a penny and has 3 wire hook-up: output volts, input volts, and ground. Being that it is one-tenth volt higer shouldn't matter because even a AA 1.5 battery reads 1.6+ when new, so I'd assume the original battery was a little higher than 2.4v. EDIT, well I misread your voltage and bought the wrong ones....again I'll try it anyways But anyways, there may be one out there with correct volts. Voltage Regulator ~ SPX29300T ~ 3 Amp 2.5V <!-- End Item Name. --> <!-- Item Description begins on the next line. -->Low Drop Out Voltage Regulator 2.5V 3 Amp Adjustable output down to 1.25V 1% output accuracy TO263 package Manufactured by: SIPEX Part Number: SPX29300T I just bought some online and will try to get mine working again.
This topic came up some time ago and I was going to build a couple of solid state sending units just to see how feasible it would be. I bought the components and the circuit board but that's where it ended. Here are the schematics for the OEM Sun sending unit and the solid state replacement...
Yes, that's the type I have with 2 batteries, and that pic shows them in a series to put out 2x1.35v=2.7v. The IC regulators also come in "adjustable" type. Not like an adjustment like a screw, rather other components can be added to one of the terminals to change the output volts. Way beyond my skills....heck I can't even read posts correctly ........and I have a tach that still doesn't work. So..you were going to replace just the box guts? ..and put in some potentiometers to adjust the needle readings at idle & high rpm's?
I talked with a guy ounce who claimed he was using AA 1.5 volt batteries in his with no modification but they had short lives anyone ever try? showrod
Yeah. My sending unit appears to only have the single battery on the right in that above Sun Schematic. It is an earlier EB unit made in the late 50s and is the solder in kind. I did some looking around and found a website discussing old cameras with the same difficulty in finding obsolete 1.35 V mercury batteries. They found this 1.35 Zinc/Air battery. http://www.ritzcamera.com/product/145140018.htm It delivers a constant steady 1.35 volts, which the camera guys demand constant and consistant power for camera needle meetering. Two can be stacked in series to give 2.7V The camera website said: Here is a website that holds the coin cell battery holders for about a dollar. Perhaps the battery receiver inside could be modified to accept this new battery, and then you're good to go with your original set up. http://shopping.microbattery.com/s.nl/sc.2/category.708/.f
so i just got a sun tach that had one of those boxes. If i build the schematic shown here will it make the tach work for my 54 plymouth flathead 6? i really want this tach to work if i can make it function.
I built one serveal months back. I had a guy at work design the circuit for me - it was a "piggy back" deal where we robbed some voltage from the "ignition" terminal. I got it all wired up and installed it, BUT then my truck wouldn't run - disconnect it and it fired right up - I don't know if I screwed something up or if something was defective in my origional sender unit - probably would have been a better idea to duplicate the entire assembly with the solid state components. Been busy with other things so I haven't got back to it. If anyone's interested I will dig through my computer and see if I saved the schematic.
I popped a couple in my transmitter just to see what would happen. The tach reads acurate, the needle doesnt jump. So far so good. I dont know what they considerd short life but mine have lasted a couple months and they were used ones when I put them in there.
HAVE SOME 555 CHIPS IF ANY IS INTERESTED IN TRYING TO BUILD ONE OF THE ELECTRONIC UNITS.JUST PM ME DEUCEMANAB COBRAMANAB@FLASH.NET
i'm definitely interested in trying to build one. basically all i do is follow that schematic using the 555 things (my brother's much better with electronics and he'll help me build this and make sense of the diagram) and then hook it up to my tach and a power source and the distributor and it'll work without the old sun box?
So, who's going to take the challenge and run with it? Charlie Led? Anyone? There has got to be hundreds,maybe thousands, of these old tachs out there and putting them back in service is just the thing for the type of cars that are popular here. I've got 3/4 of these old buggers and I'm in for some conversions if anyone steps up and produces, and I'm sure there are many more. Frank
i will most definitely try to build one of these so i can get my old tach to work. i guess i'll go pick up the parts to build one of those from the diagram and let ya'll know how it works out.
I'm new to the HAMB but I have converted one of these tachs to an electronic circuit so it gave me a reason to join and share my experience. The circuit I used was published by National Semiconductor and used one of their IC's that was made for tachometers and other frequency measuring applications. It was advertised as being very accurate (linear). While testing the circuit with the Sun meter it became clear immediately that the meter movement was very non-linear; as the frequency (RPM) increased the meter would read higher than expected. I believe this was designed in to compensate for the simple relay operated transmitter that was used to drive the meter. The relay circuit probably couldn't respond fast enough to supply enough current to the meter at the higher RPM,s. I THINK they accomplished this higher range extra sensitivity by adding weights to the meter movement to make it more sensitive at the higher end of the scale; thus requiring less current. I was able to add some feedback to the circuit I used to balance this out but It was very time consuming to calibrate the meter and its really a"band aid" solution. It would be better to rebalance the meter movement (if that really is the problem) but that is also a tricky thing to do without damaging the movement. The conversion by Williamson's looks better after considering all this. It would be interesting to know if they are reworking the movement in this manner and what kind of accuracy and linearity they guarantee. As far as the battery replacement issue, I haven't any opinion on it.
A while ago I had posted a pick of inside of a transmitter that Williamsons did for my dad's car. Most was covered with a goop that made it hard to see what was actually done. I don't know if they do it to cover what they did, or to protect it, but I wasn't about to scrape it off. I don't think they modified the head. FWIW I've been using two AA batteries in mine for going on 3 years now. The SAME batteries, but I take them out in the winter. It's reasonably accurate. Hey, the needle moves when I hit the gas with my flathead. If I was actually running any sort of performance that demanded an accurate tach I would do something else. I'd like more info on a do it yourself conversion that's been tried and prooven.
Sorry to bring a VERY old post back from the dead but..... Never posted before, but spent a bit of time reading. Thought I'd add my 2 cents. I built the 555 transmitter from the design on this post. I just tested it on my mates 58 Biscayne. I couldn't find a 200K potentiometer (adjustable resistor) and installed a 250K (it all I could find at the time). Well, it works (mostly). The potentiometer is not allowing the correct adjustment of the tach, but it is certainly getting a signal through. Happy to send photo's or details on where to get all the components including a universal pcb that I used (www.dse.com.au) It will all fit inside the original sun sender without any modification and will also be able to hook up to the original tabs on it without having to do anything that cannot be reversed. All up, only cost $23 AU to build and a couple of hours of head scratching. I can certainly post how it goes AFTER the new potentiometer. FYI - I am using a 1961 Stewart Warner tach and have a Sun Sender that I was going to use.
Thanks so much for the update!!!!!! Could you please show us what you did? It would have made a great tech week post!!!
I know this is an old post, but maybe someone can add some new facts in this dilemma, finding the right battery for the transmitters. I found this and i quote. "For replace the outlawed PX625 battery of the Leica CL, you can use a Weincell zync air MRB625, an 1,35 volt battery. As option, there is an MR-9 adapter, that have a built in micro electronic circuit, that reduce the 1,5 volt of the silver oxyde battery into 1,35 voltage of the ancient and outlawed PX625 mercury battery." Elrod, this is eventually something for us, with just one battery.
don't know if this helps at all, but nickel metal hydride batteries (nimh rechargables) that you can buy right at the store are 1.2 volts not the 1.5 of a normal alkaline battery. I found some companies that list nimh batteries as usable for long term storage, keeping 90% of their charge for 6 months. once they run out, ya just recharge em. something to try to see if there is a difference between the alkaline batteries.
I am retiring from my day job on April 1st so maybe I'll have some time to devote to this project. I still have the components and breadboard and a tach, I'll put it back on my to-do list.
I'm glad this post is still kicking, I hope there will be some new info soon. FWIW i'm still running the same AA batteries in mine, I'm on year number three with the same ones, no problems yet.
I was given a 6v 6cyl Sun today. It's an EB 2A so I guess its a solder in battery. It only goes to 4K so I don't know what I'll use it for,if anything. Even my 6s turn more than that. It's got to be early I'm pretty sure the truck it came from couldn't have been used after the late '50s. When did they first build these?
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