[Milsurplus] 24 volt power supply in 12 volt vehicles

[Peter Gottlieb]

Neat idea!


Peter

> On Feb 26, 2018, at 5:52 AM, Bruce Gentry <ka2ivy at verizon.net> wrote:
> 
> The discussion about the solid state vibrator modules reminded me of a very sucessful project I did almost twenty years ago. I wanted 24 volts in a pickup truck to run radios. There are all sorts of power supplies possible, but I happened upon an inexpensive one that can be built easily.  The first requirement is an older solid state power inverter for making 120 volts AC from 12 volts.  The one I used was built by Tripp-Lite, but I am sure there are others as well. It is the older, conventional type with a large transformer, not the ones of today.  The 12 volts went into the center tap of the transformer primary, the switching transistors grounded the ends of the primary alternately. When one bank of transistors is grounding one end of the primary, the other end is at twice the input voltage. I used a pair of large diodes to rectify the 24 volts.  Athough I had a filter condensor for the 24 volt output, it was smoothed and stabilized further by two 12 volt batteries.  The truck has a 120 amp alternator, so making 20 or so amps at 24 volts isn't a strain. RFI from the power supply is quite low, you have to hold a pocket radio tuned to the bottom of the AM band near it to hear anything. The truck has a ordinary  mechanical injection diesel engine, so there is no RFI from vehicle systems either.
> 
>      Bruce Gentry, KA2IVY
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