View Single Post
  #4   Report Post  
Old January 16th 05, 11:36 AM
Geoffrey S. Mendelson
 
Posts: n/a
Default

In article , jrd wrote:
Hi, I have a device that requires 12vac but need to use 12vdc as a
source. Is this possible? I see all kinds of 12vdc inverters around but


Depending upon the type of load, you could make an inverter out of a
60Hz oscilator and a cheap car stereo amplifier. This would not work for
a large motor such as a drill or mixer due to heavy startup drain,
but a small motor such as a clock, old tape recorder/vcr, telescope
positioning unit (clock drive) etc would do fine.

The trick is to get a good 60Hz sine wave. Besides an resistor/capacitor
oscialtor, which would be fine for most things that are not truely
time critical, you could do a digital thing with a multiple of 2 such
as 32768kHz (common clock/watch frequency) and a counter circuit to
cut the pulses down to one every 60th of a second. You would then need
to smooth the square waves (pulses) into sine waves and then amplify
them to your 1 amp at 12 volts.

Geoff.


--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
IL Voice: 972-544-608-069 IL Fax: 972-2-648-1443 U.S. Voice: 1-215-821-1838
I may be an old fart, but I'm a high-tech, up to date old fart. :-)