Based on Sam Goldwassers SG-IY1 design
The following photo's are of the PSU I built using diagrams from Sam's Laser FAQ. This power supply was built for the Uniphase 2214-40 laser head. This power supply is capable of delivering up to about 12 Amps to a plasma tube. I will be building a second supply similar to this without the filament subsection and with a larger passbank to run some linear arc lamps I have for use in a CW yag laser project. I apologize for the images being so large but I believe detail is important. The power supply may not be a beautiful piece of craftsmanship, but it works pretty good!
Please click on the images for higher resolution versions.
Below: Front perspective view of the power supply. The pass bank is in the rear-left qudrant of the supply on the aluminum heatsink underneat the analog ammeter I have been using until I get a decent digital gauge like I am using for the voltmeter. The filter capacitors are the two big blue cylindrical objects on the right. The filament transformer is in the front-left quadrant with the volt-meter mounted directly to it. Just to the right of the filament transformer are the power resistors. There are two 1 Ohm resistors, and one .2 Ohm Resistor.
Below: This is the rather ugly front panel view. I am more interested in functionality, than I am appearance, as is obvious. To be fair to myself this case is from an old power supply and the front aluminum panel was chock full of holes I did not need and I had to fill them in with an aluminum alloy called sold under the name 'Durafix'. This alloy has a melting point of 732°F If you are trying to save a few bucks and have a hot torch, this stuff works excellent for filling in holes, welding aluminum and other stuff. Try it out sometime!
The panel is as follows from left side:
Red 15 Amp Breaker/Power Switch, remote trippable.
The Blue indicator is the 'mains power' light, this stays lit
when the PSU is plugged in.
The Red indicator
below that is the 'Power on'.
The Green indicator
is the filament power on.
The Red button below the
Green indicator is the filament on button, it causes
a relay to close and latch itself to turn the filament on.
The Red indicator next to the Green
indicator is the 'DC power on' light.
The switch below it is the 'DC Power'
enable switch.
The small silver colored knob is the passbank power
adjust.
The black knob to the right of that is the variac control for
filament current adjust.
Below: This is just a top down shot of the panel. From the left. The variac is for adjusting power to the filament transformer.
Below: These are the power resistors required for current limiting. They are fairly large, but the aluminum heatsink power resistor style is much smaller than other types of resistors out there, and they are much easier to mount. Please note that these get fairly toasty when the PSU is running and I will be placing a fan directly over them to help keep them cool.
Below: Just another view of the PSU.
Below: Another shot of the PSU. The digital gauge reads the DC voltage directly off the pass bank output, so I can track the voltage being fed into the argon tube at all times. The analog gauge reads the current and is placed between the center tap of the filament transformer and the pass bank.
Below: This is my make shift pass bank. I used an old chunk of heatsink from an old line printer and mountd the transistors to this using mica transistor isolation tabs and heatsink compount. I then used strips of circuit board as the main conductors between each transistor.
Below: The small circuit board is the pass bank drive circuitry. In most argon supplies this is built right onto the heatsink with the pass bank, but in the case I did not do this since I wanted to isolate sections of the PSU for easier troubleshooting (look at all the wires in this thing!). This board is built out of a mixture of through hole and surface mount components(on the bottom) so if it seems to be missing a couple of components, you know where they are. Also shown are the fat filter capacitors rated at 3400uF @ 200 Volts.
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