I just wanted to let you know if a little project I did recently. The idea was to provide regulated 12v and 5v supply voltages for powering astro equipment from a car battery. Behind this was the fear that one day I might actually have a 'blond moment', connect things up the wrong way around, take out a lot of expensive kit and start crying.
It would also stabilise the voltage and provide a better electrical environment for all the sensitive equipment that we astronomers use.
The Spec. was:
1) Reverse polarity protection in case of incorrect battery connection
2) Stabilised regulated 12v up to 8 amps
3) Stabilised regulated 5v up to 3 amps for USB hubs
4) Clean glitch free control of power on/off
5) Multiple 12v cigar sockets that were waterproof and locking (so equipment doesn't get disconnected accidentally.
6) work off battery voltages between the range 9-15v
6) The electronics must have a low power footprint.
What I ended up with was all of the above is a box about 8" x 6" x 4". On one side are three locking marine 12v cigarette lighter sockets, on the other a power switch (which disconnects the unit from the battery) and a power up push button (tells the PSU to power up). On the bottom there are 2 x 2.1mm jack sockets for 5v power and 4' power cable with the battery connectors.
The PSU is a stock Car ATX PSU from LinITX in a plastic maplin box. The PSU is very efficient, gives off virtually no heat so works well inside a sealed plastic box. The PSU is rated at 120W and takes an input voltage of between 6 and 32v making it very versatile, also all the output curcuits are short curcuit protected.
It was very easy to construct - the most tricky part was drilling holes for the 12v sockets ! Cost approx £60 - yes, expensive but compared to making a mistake I thought it was worth it !!
If anyone wants more details then let me know.
Robert
Have you got a picture of it?
That's a great idea Robert. I wouldn't mind seeing a piccy of it completed.
One question - what *does* happen if you connect it up reverse polarity?
Mark
QuoteOne question - what *does* happen if you connect it up reverse polarity?
Nothing i.e. you dont get any power.
Will take some pics tomorrow...
Have posted pictures and description on Flickr http://www.flickr.com/photos/29673723@N04/ (http://www.flickr.com/photos/29673723@N04/)