Quote:
Originally Posted by alistairsam
Hi,
if the +12v is used as a scope supply, dew heater straps, cameras, etc, won't this load draw be sufficient to turn the unit on rather than the resistor?
A CCD requires 12v 4A, 3 straps around 1.2A, scope around 2A, so this PSU would be a good solution.
anyone know what part of the motherboard acts as the load to turn it on? has to be an easier way to turn it on without wasting power as heat via the resistor.
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I haven't used a computer PSU for astronomy but I have as a workbench supply. I just hook up a computer fan to it and that seems to be enough load to let it fire up. Alternatively if you can find it an old AT PSU, be careful though as the switch on these is 240v and does bite. These often are only 200w and usually are very old.
Another thing to try is a laptop PSU then plug it into a breadboard wired with some regulators such as the LM317t or LM78xx These will give you 1.5a but there are higher current ones. This design allows you to split the power outputs and individually switch stuff easier. Laptop PSU's are also smaller but usually put out 19v 5a instead of 12v 30a.
http://en.wikipedia.org/wiki/78xx
A final thing to try but a word of warning these things seem to get quite hot so the case may need a headsink attached but dealextreme and ebay sell regulated 12v power supplys. I picked up a little 2a unit and it was like $7 and provides 240v to 12v 2a but with massive heat. Larger units are available and many guys here use them. connecting an addon board with a LM7805 for example will also give you 5v regulated for powering USB hubs etc. a LM317 with the right resistors will give you an output to make a dummy camera battery so you can run you DSLR from mains power.
http://www.ebay.com.au/itm/AC-100V-2...item19d3e10219