12volt to 6 volt power supply for truck

[ewertro]

Hi there,
I am looking for a simple power supply for my truck that will supply 6v at about 1-2 amps. Thanks for any help in advance.

 

[dknguyen]

Buy a 6V linear regulator and stick a giant heatsink on it. Like an LM7812. The datasheet will have the circuit you need.

You can also go to your local hobby store (the kind that sell radio controlled helicopters, planes, trucks, cars, and boats) and buy a "battery eliminator circuit" which converts 12V to 6V (or 5V).

Like this one:
https://www.dimensionengineering.com/SportBEC.htm

 

[ewertro]

perfect, thanks.

 

[KMoffett]

A 7812 is a 12v output regulator, not a 6v output. 7806 regulators are not as common as 7805's (Radio Shack 276-1771). But you can stick 2 forward biased diodes (1N4001) in series from the common terminal to ground and get ~6.2V out from the 7805. Don't forget to add two 0.1µF capacitors between the input and common, and the output and common to prevent oscillation.

Ken

 

[jtexas]

LM317T at radio shack, adjustable voltage regulator.

 

[dknguyen]

Oops. yeah for some reason I thought 12V and wrote LM7812. Doesnt make much sense. You can use an LM317 though with two resistors which let you adjust the output voltage.

 

[RODALCO]

Above regulators 7806 gives 1 amp.
The 317 gives 1.5 Amps max.

If you need more current, perhaps drive a 2N3055 via the regulator and you can access 4 Amps easily.

 

[RODALCO]

https://www.qsl.net/yo5ofh/hobby circuits/power_sourse_circuits.htm

This link has some power circuits which can easily be modified to 6 Volts.

the LM 317 here actually drives a 2N2955 PNP power transistor

Hope it helps,

Regards, Raymond

 

[stevez]

A friend ( maintains/repairs commercial two-way radio systems) recommended I install a Transient Voltage Suppressor (TVS) with a fuse on my mobile equipment. The TVS is installed across the line and if the voltage rises above a certain point (depends on TVS selected) the device conducts - behaving as a dead short. The fuse would be located so that when this happens the fuse melts and opens the circuit.

I mention this because you could make a mistake in wiring - or the circuit you choose could have a failure mode that allows the full 12 volts to pass to your 6 volt device. As I recall, a TVS is cheap. I am sure that someone here can provide a specific part number or possibly an alternative that accomplishes the same thing.

 

[RODALCO]

Crowbar

That is called a crowbar circuit.

You can do that with a zener and a Hi power SCR.

The zener can be a 6V8 one which triggers a 6 Amp power SCR which takes out the supply fuse.

Good idea and cheap to implement.

 

[stevez]

As I understand it, there are a number of ways to provide "crowbar" protection. Whether zener/SCR or TVS it seems cheap - compared to the possibility of damage. My friend was telling me that while not common it's also not rare for a vehicle system failures to cause voltage levels to rise substantially over normal voltages.