🚀 go-pugleaf

massoud@chemteca.sdsu.edu (Massoud Ajami) writes:
>In article <1992Aug25.192312.22175@javelin.sim.es.com> pashdown@javelin.sim.es.com (Pete Ashdown) writes:
>>Alright, so I admit it, I've forgotten a bit of my physics.  The question is
>>this:  I recently purchased a small transmitter that can work off either a 9
>>volt battery or a 12 volt power supply.  I happen to have a 12 volt power
>>supply that I use to power my laser, but it is at 2.5 amps.  I realize that
>>this amperage is far more than I need for the transmitter, but is it too much?

>Let me tel you this: do you know that your car battry can supply like 300 
>ampers if it is needed, but doesn't do any damage to your car radio! Having 
>more supplied current to a device is like going to "all you can eat" place, 
>any device draws as much current as it needs, but you can not under supply 
>the current.

One thing to be aware of -- if the 12V power supply is a computer power supply,
and if it is a *switching* power supply, it may well have a _minimum_ current
requirement in order to maintain regulation.  If the power supply has a big,
heavy transformer, it's most likely a linear supply, in which case it will be
happy loafing at a light load.  If the supply came out of a peecee, and if the
transmitter is a tens-to-hundreds of milliamps load, you might be in trouble
(easily rectified (heh), though:  put a 12ohm, 12W resistor across the power
supply to guarantee an amp of output current, which should keep the supply
happy.  Maybe 24ohms, 6W (for .5A) would do.).