Electrical: Cheap volt drop

[kxet]

I have a few cell chargers that drop 12 vdc to 5.3 vdc. 530 milliamp. Could be used for gas guage. Can be adapted to hide under dash or?
Lot of them around. Have fun.

[RadioRoy]

These will do a much better job and are even cheap enough for a CASO.

http://www.ebay.com/itm/LM2596S-Adjustable-DC-DC-Converter-3-40V-to1-5-35V-Step-Down-Power-Supply-Module-/231148352653?pt=LH_DefaultDomain_0&hash=item35d183f48d

[Zenwren]

These will do a much better job and are even cheap enough for a CSAO.

http://www.ebay.com/itm/LM2596S-Adju...item35d183f48d

I've never seen these before, are they better than the "runtz" type resistors? I assume one per gauge is needed?

[Jeff_H]

I took a quick look at that ebay unit...

Its a switch mode regulator. Runs at 150kHz. Depending how good a design they did, you may have problems with noise picked up on your AM radios. From the looks of it, I don't see much in the way of filtering though. Also, despite what the ad says about using it on 40v, I sure would not. I see 35v rated capacitors used, especially the input one. At least it does look like they put in a diode on the input so if you hook up the power input leads backwards it won't fry it. I doubt you could get 3A out of it either except under the most idea conditions. That particular IC is pretty "old" as it was originally released about 1999.

For all that, its pretty cheap and may work perfectly fine for a lot of things. Certainly to run 6V gauges off 12V would be one of them, assuming it doesn't cause issues with interference on the radio. If it does, there are things that can be done to mitigate it though.

Amazing though that someone can make these boards and sell them for under $2. I couldn't find the big IC used on there for less than that, even if I bought 1000 of them. If my company was making those, probably would have to sell them for $10-15 at least.

[RadioRoy]

I've never seen these before, are they better than the "runtz" type resistors? I assume one per gauge is needed?

Runtz are not resistors. They are voltage regulators. There is a big difference.

The voltage regulators I listed are designed to handle 3 amps output. If memory serves, the gauges only draw around .135A each, so you could hook both sets of gauges to one regulator.

It's only a few dollars and a few minutes/hours of time.

[Zenwren]

Runtz are not resistors. They are voltage regulators. There is a big difference.

...I knew that was coming, that just seems to be what everyone calls them.

Seriously though thanks for posting these. I ordered a few of these to play with. Now I've got to decide between the $50 marine grade shunt or the $6 Chinese one for my amp gauge!

[RadioRoy]

... Now I've got to decide between the $50 marine grade shunt or the $6 Chinese one for my amp gauge!

You don't need a shunt for the amp gauge. It will work just fine on 12 volts.

Maybe you could explain all the changes you are planning to make, so we can vet the process. There is a lot of misinformation on what must be changed for a 12 volt conversion, and what does not need to be changed.

If you tell us what you plan, we can set you straight before you make any expensive mistakes.

[Zenwren]

My wiring harness was shot so I'm putting in a kit from speedway with a 12v alternator. I understand the shunt isn't required but it sounds like cheap insurance. Not sure if I'll change out my blower morors to 12v or try to get the 6v ones to work. Any thoughts?

Oh and another question, what the heck is a CSAO?

[gordr]

Yeah, no shunt needed for amp gauge. All other things being equal, it should have less current to pass used in 12 volt service than it did with 6 volt. That's one of the reasons manufacturers went to 12 volts; they could get away with thinner wires, and save a lot of money. Blower motors respond pretty well to using resistors to slow them down, after all, that's how lower speeds are implemented in many models. But if they can be easily changed for 12 volt motors, as in the C/K cars, changing them is as easy. The wiper motor probably should be changed, as they are subject to stalling under load (ice, snow), and stalled motors will burn out real quick if supplied with overvoltage. Wiper motors work hard, blowers not so much.

[larkregal62]

zenwren that's CASO which is Cheap As*ed Studebaker Owner-- Gordon

[northern]

I just went through rewiring and completing the conversion on a '54. Bear in mind that there is more than one way to do most of this stuff; this is what worked for me.

The only gauges that you need to reduce the voltage for are the gas and temp gauges. The cheap in-line Runtz units work well for those. There is no point complicating things by reducing the voltage for the amp gauge. The oil pressure is mechanical, so nothing needed there either. If you have a clock - well opinions vary on that one - I'm still thinking about that.

For the wipers, heater, and defroster motors, it might be best to change them to 12 volt units. For one thing, the 6 volt motors may be old and more or less worn out. For the heater and defroster motors, NAPA part #M816 fits well. It's listed as a GM unit from the 1960s, but is about the right size and fits well.

For the horn, I installed a new 12 volt relay and a set of 12 volt horns. Someone had taken the horn system out of the car, so that was as easy as anything else.

For the radio, I went with an Aurora Designs conversion, done by a fellow in Tennessee. He did a great job. The radio looks 100% original but has all the modern features, including an input for various devices and great sound.

The car has a 1 wire GM alternator.

Even though the car is completely rewired, I'm always concerned about electrical shorts in any old car. In addition to the fuses, it has two fusible links coming off the solenoid to protects the circuits. Another thing that one could install is a master disconnect switch. Spend $30 or $40 on a good one made in North America, and stay away from the cheap Asian switches.

[Zenwren]

Are you sure that M816 is the right number? I can't find any reference to it.

[northern]

M816 is what is marked on the bill and the box. On the motor itself, it has the number 14511. It's a UNIMOTOR brand motor - should be easy to find. It's about $60 here in Canada, but probably less expensive south of the line.

Someone had recommended a mid-60s Mustang blower motor (M4825), and I bought one of them too from NAPA. It was about $10 less, but I don't recommend it. The M816 is a shorter unit, is close to the original size, and fits a lot better. The Mustang motor also has an unnecessary hole - about 3/4" in size - in the side of the motor housing. For the Studebaker, that's not needed and just creates a spot for moisture to enter. After sealing off the unnecessary hole, I used that one for the heater blower, tucked up inside the fender where it won't be seen. I probably should have returned it and bought another M816, but didn't bother.