Thought I'd post this one since we get a lot of questions on it, here's a cheap 6 volt reducer. I don't like those resistors (they get too hot) and I've tried those expensive voltage drops (fried em') How about a cell phone charger! I found this at an electronics surplus store. It takes 12 volt DC and reduces it to 6 volt DC at 2 amps. Cut off the cigarette lighter end and hook it to 12 volts. At the other end is a jack, open up the charger and solder on a couple output wires. Hook up the output side to your gas guage and that's it! We've beeen running them for a couple of years now with no problems. And it was only $1.98!! MOD EDIT: Original Thread here: http://www.jalopyjournal.com/forum/showthread.php?t=8274
its a shame this is on page 2... Also, if ya ever run across a device called a 7806.... its a 6v regulator, looks like a big transistor... 3 pins, one takes up to 35v in, center is ground, and the third is regulated 6v out... there more common bretheren are 7805 and 7812... 5v and 12 v respectively.... Radio shack carries those, so you can go in and at least see whatthey look like.... but they are not 6v... There are tricks to making the 5v one do closer to 6v, but its beyond the scope here... the cell phone charger is much easier! THEN, if you are ever tossing something electronic, check it out for one of those regulators, they are common... you can unsolder it, and use it again...
After ya get done with hooking up the gage. Take the cigerette lighter end and put some alligator clips on the wires and use it for a tester. Just plug into the lighter outlet and you can test componants like power windows, radios and such with out running a wire clear to the battery. Thrift stores are a great source, just use your imagination.
great post. the cellular charger is an easy way to go. burndup is right on the money, easy to find 6v regulator at some larger electronics stores, but radio shack carries only 5v and 12v because its common for computers. i got a 6v at FRY's electronics for under a dollar. 3 wires, ground, 12v in, 6v out. and much smaller than the charger.
You mean amps? Try 6-10 amps for 6V fan motors. And they are inductive loads, so unless you have a voltage regulator in the 20-40 amp range, you will be looking at smokey joe for a regulator! BTW: I doubt that these phone chargers are any good above 250ma or 1/4 amperes. They are meant to charge lithium ion and ni-cad batteries which require a very small amount of current for charging. Most fuel gauges will draw more current when reading full as to reading empty, as the sending unit decrease in resistance when full.
78xx and 79xx have a thermal protection. They can provide up to 1 or 1.5 amp with a dissipator, but they won t burn.
I use a zener diode NTE 5118A and resistor to get 6V for the fuel gauge. Cheapest and simplest method.
I don't remember the resistor value. It depends on your battery voltage and fuel gauge current draw, but 1/2W rating is fine. The zener is 6V and rated for 5W and will last forever.