Post Sat Jun 30, 2018 9:09 pm

Re: L110 dash lights and sockets

cornbinder89 wrote:One for all is fine, If I were going to "convert" a 6 volt vehicle, I would sit down a figure out the stuff that is hard to change to 12 volt (wiper motor, gauges etc) and figure the max current and get a solid state convertor that could handle the current, and have one "6 volt buss" to supply these items.


I thought about doing this, but the wiper and heater together, plus margin, would come in at around 10 amps. The wiper motor draws quite a lot of current when starting up.

Terrell wrote:You can buy the L7805 voltage regulator very cheap on epay, doesn't look to be rocket science to wire them ( two wire per regulator)...I just didn't think the gauges would have that much of a current draw.....


7805 will probably work. A better choice is the LM317 or LM338. These can be set to any voltage at least 1.25V lower than the supply. I would aim for about 7 volts output, same as a 6V generator charging the battery. Good heat sinking will allow all the gauges to run from a single regulator. I think I calculated about 1.5A current as a worst case scenario.

Good timing on this post. I could have bought a regulator, but I decided to build my own entirely from parts in my junk boxes. This is what I came up with:

Regulator 001.JPG
Parts I had sitting around

Regulator 002.JPG
Chassis drilled and ready

Regulator 003.JPG
The regulator's heat sink tab IS NOT GROUNDED. It needs to be insulated with a special thermally-conductive electric insulator and plastic washer or it will short out. Thermal grease helps fill in minor gaps but I was fresh out.

Regulator 004.JPG
Regulator pinout. Same for LM317 and LM338.

Regulator 005.JPG
All wired up.

Regulator 006.JPG
Assembled and ready to test

Regulator 007.JPG
Easy mounting from the bottom with 10-32 rivnuts

Regulator 008.JPG
Bench test. My favorite Radio Shack indicator lamp can be seen here. Used one as an indicator to show that power is on and coming from the regulated side.

Regulator 009.JPG
Mounted to the steel "shelf" under the dash. Red wire goes to the key switch. Blue goes to the gauge bus. Black to ground. The big ceramic resistor below is unrelated. It is part of the alternator conversion I did a few months back.


I tried it out today for the first time. Works perfectly. The regulator resistors I used (2.2K and 10K ohm) were a bit out of tolerance and I ended up with 7.3 volts instead of 7. Close enough that I'm not going to worry about it.