repeat

--
Tater
President of MARS Club (NAR #660)
www.mars-rocketry.com
KC9ESF
NAR #79654 L1
EAA #703312
remove spam spelled backwards to reply


"tater schuld" wrote in message
...
need some advice, I may need to drop a 12v battery power supply to lower
voltages, like 9 or 6 volts. while a resistor network would do this
easily,
it apears that for high current applications that this would be wastefull.
anyone ever thought of a dc to (lower) dc converter that is a bit more
efficient? cost and weight are a factor so a dc to ac to transformer to dc
wont fly (ack, sorry about the pun)

--
Tater
President of MARS Club (NAR #660)
www.mars-rocketry.com
KC9ESF
NAR #79654 L1
EAA #703312
remove spam spelled backwards to reply

There are a number of regulators available

78XX series, can drop, from memory 30V input down to 12, 9, 8, 5 as
standard, with just a few extra parts, ie, one capacitor.

Paul

need some advice, I may need to drop a 12v battery power supply to lower
voltages, like 9 or 6 volts.

LM317. Add two resistors to get exact voltage you need. Fine for 9V. For
6V, you get get a little more efficiency by using a switching regulator but
at the cost of more complication.

John Musselman
WB6UHF

i am familliar with the 78xx series, but i am a bit worried about the heat
output from such devices.

in a spaceraft, the heat will build up. i was wondering if there were some
other options.

--
Tater
President of MARS Club (NAR #660)
www.mars-rocketry.com
KC9ESF
NAR #79654 L1
EAA #703312
remove spam spelled backwards to reply


"loedown" wrote in message
...
There are a number of regulators available

78XX series, can drop, from memory 30V input down to 12, 9, 8, 5 as
standard, with just a few extra parts, ie, one capacitor.

Paul

The regulators come in various sizes, from the small TO92 packages, which
can deliver 100mA, or the TO220 packages which will deliver upto 1A. If the
spaceships are metal, that will provide an ideal heatsink for the TO220
packages. I recently did a job on a JVC DVD player, honestly MR. JVC, who
would put an MPEG decoder IC on the bottom of a drive with about 2 mm of
clearance for air and wonder why the thing has a hissy fit after 40 mins of
playback or so. So not able to heatsink / superglue a heatsink on the top of
the chip, I superglued a small fan onto the mainboard, bolted a 7812 onto
the fan's frame and ran 2 leads back to a +24 V rail, dropped a cap across
the +12 / GND and thing hasn't played up since.

Paul