Computer Power Supply. Amateur Radio Conversion For Cheap +12 vdc Power March 17, 2003. Advantages. Supplies are Readily Available They are Inexpensive ($1) 50 watt Radios Only Need 10-15 Amps New Supplies Have Higher Wattage 100 Watt HF Rig Potential Or Parallel Supplies. Requires.
Amateur Radio Conversion
Cheap +12 vdc Power
March 17, 2003
Concern For Safety
Seems to be the “Norm”
From Supply Output
Lots of differences
Blk = GND
Red = +5 vdc
Yellow = +12 vdc
Blue = - 12 vdc
White = - 5 vdc
Caution: Heat Sinks May be Electrically Hot!
I = 5v/5Ω = 1A P = 5v x 1A = 5 watts
Only +5 used for regulation
Decrease Voltage On Pin 1
Or Decrease This
R2 WHAT IF?
Note: After the presentation an additional slide was added to further explain this spreadsheet (Next page). Also if you double click the picture of the spreadsheet it will open Excel so you can look at the formulas. Finally the spreadsheet was changed so you can enter a different Reference voltage and all values will change accordingly.
R2 WHAT IF?
Yellow Indicates numbers that can be changed
The TL 494 will try and maintain the reference voltage by raising the output voltage.
This “constant” is used to find the current that must flow through R! at this voltage.
C = 1.254/R1
Only in the parallel example.
Adjust Resistance for 13+ volts 13.5 volts
This is How I
Supply for 12 volt
Note:Ken’s Supply was Modified for 12 volt Regulation Only and the Supply Wouldn’t Output Until the 5 Ω Resistance was Added to the 5 volt Output
Watch What You Touch 13.5 volts
Just Because You can Increase the Voltage Doesn’t Mean You Have Regulation
Make Sure You Know How to Power Up the Supply
Getting the Cover Off of the Supply Can be a Challenge
¼ Watt Resistors are Hard to Read…
If You Can Find the Resistors From Pin 1 to Ground You Can Just Put a Resistor in Parallel With Them Most of the Time
Some Supplies Are Almost Too Full to ModifyLessons Learned
Note: With Only One Supply Turned On (In Parallel), Both Fans Run
The End 13.5 volts
Created by KØGL