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View Full Version : reducer , 12 to 6 volts.



curt
02-26-2010, 03:05 PM
I found this on the Kaiser chat, It's how to build your own voltage reducer, I have not done this. Perhaps a few engineers will evaluate this inexpensive device. http://www.jalopyjournal.com/forum/showthread.php?t=448038

tbredehoft
02-26-2010, 03:31 PM
I went thru this agony a year or so ago, With Jeff H's help I was able to construct an converter with an input of 12 volts, out put 7 volts,up to 8 amps load.

Here's a drawing of what it might look like, if the heat sink wasn't in the way. All the components are specified on this drawing.

http://i46.tinypic.com/nmgcpt.jpg

Email me at tbredehoft(at)alink.com I'll send more pictures and suggestions. It ain't easy, I built three, cost around $35.00 total.

I run my clock off one, it's on all the time, the fuel and temp gages run off another, it's switched with the ignition.

[img=left]http://www.alink.com/personal/tbredehoft/Avatar1.jpg[/img=left]
Tom Bredehoft
'53 Commander Coupe (since 1959)
'55 President (6H Y6) State Sedan
....On the road, again....
'05 Legacy Ltd Wagon
All Indiana built cars

royvaldez
03-05-2010, 04:41 PM
I just need to know what the overall (total) current would be at 6 volts. A long time ago, we used to just put a power resistor in series with the positive terminal and drop 6 volts from the 12 volts. We can regulate it similar to the circuit on that this blog . If there is 5 amps of current on the 6 volt line, as an example, that is 30 watts of power. I will need to add a heat sink to the circuit. There is a lot of ways to avoid the heat sink issue. I could always have separate regulators for guages, the radio, and other items. Then each one could be reduced to a couple of amps, which is still 12 watts, but probably OK on a PC Board without a heat sink. Can anyone advise. Roy

gordr
03-05-2010, 06:50 PM
Tom, do either the regulator chip or the power transistor need to be insulated from the heat sink?

Gord Richmond, within Weasel range of the Alberta Badlands

tbredehoft
03-05-2010, 06:55 PM
They are both mounted on the heat sink. The regulator chip is common to the heat sink, the transistor is not electrically connected, but is thermally bonded to it. Does this make sense?

[img=left]http://www.alink.com/personal/tbredehoft/Avatar1.jpg[/img=left]
Tom Bredehoft
'53 Commander Coupe (since 1959)
'55 President (6H Y6) State Sedan
....On the road, again....
'05 Legacy Ltd Wagon
All Indiana built cars

woodysrods
03-06-2010, 12:01 AM
Got hooked up with that exact drawing at an electronics store 30 years ago. Used it on my 49 Ford touble free since then. Mine is mounted on a 2 1/2" x 3" heat sink which makes it ideal to mount anywhere you want it as a unit. But, there was a electrical wizard in the store when the counter guy was drawing the wiring diagram for me, and he said to sell me a #7806 which drops the voltage to exactly 6 volts. Have made numerous ones since. Original cost me $3.80 but the last one was near $5.00.
Good Roads
Brian

Brian Woods
woodysrods@shaw.ca
1946 M Series (Shop Truck)
http://i980.photobucket.com/albums/ae283/woodysrods/Concunully004.jpg