A modification to the 12V 30 Amp power supply. This version uses an
LM317 to provide a variable 1.5 to 37 Volt regulated output with
currents
up to 30 Amps. Max has built his power supply into an old computer case
and can be seen on YouTube under Project Icarus.
Notes
I wanted an adjustable power supply from 1.5 volts to 37 volts, based on
the LM317 voltage regulator chip. Simple to remove the 12 volt
regulator
chip and add the LM317 chip and a 240 resistor, a 10k pot and a 1N4007
diode. Just as easy to insert any of the other voltage chips as well.
I used an old computer tower to house my project, used the heatsinks
from the computer power supply for the power transistors.
The heat sink for the LM317 came from an old TV, and the heat sink and
fan for the bridged rectifier came from the old computor processer.
I found the transformer at a flea market.
Also added was a small transformer from an old radio. Rated at 14
volts and small amps.This transformer powers two 12 volt regulator chips
wired
together on the same heatsink. Wired together there output is 12 volts
and 3 amps. This is power for 2 fans and power for the digital volt
meter and
amp meter. The volt meter is powered at 5 volts, so another 5 volt chip
was added on another circuit board. Digital amp meters use a shunt to
measure
the amperage, and the power supply needs to be isolated, easy enough,
just use an isolation chip designed for this purpose.
Also I used 10 amp output jacks, plus 10-24 bolts with wing nuts. The
bolts are for 10 to 30 amps.
Here in the USA, we use 110 volt mains and 220 volt mains. The
transformer I found can be wired for eithor input, and can can be wired
as 16 volt or
32 volt output. 16 volt AC through the bridged rectifier and into the
47,000uf capacitor, comes out as 19 volts. This is caused by the voltage
ripple
peak into the capacitor. This caused a problem because the 32 volt AC
input comes out as 44 volt DC, and the LM317 chip is listed as 40 volt
maximum.
So currently I am using the 16 volt AC output from the transformer.
After some experiments I plan to try the 44 volt DC and see if the LM317
can
handle it.
No comments:
Post a Comment