I received many e-mail from people asking me how the capacitor charger work.
If you put, lets say 16V on a capacitor that needs to be charged then it would start to charge very fast and then slow down the closer it gets to 16V (look at a capacitors charging curve).The last 2 to 3 volts can take 75%  longer than the first 13 to 14 volts. To overcome this slow down effect we need a more constant current and it's done by increasing the voltage to +- 36VDC (rectified 24VAC). This DC voltage is used to charge the cap and the processor turns the charging mosfet off within 4uS when it reached it's set point (max 20V).
If the set point is lower than the capacitor volts, the processor will turns a mosfet on that connects a resistor bank to discharge the capacitor. EASY HUH?

The photos shows the LCD display with a 1 Farad Pro Ice capacitor that has been charged to 19.1VDC with a switching (processor controlled) rectified 24VAC.

TAB WELDER 3D UPDATED 10/25/2009

TAB3d

I made many changes to make this board easier to build. I moved some of the components around to make more space for the heat sinks and I replaced some of the very small surface mount components with bigger ones. I also made some of the circuits wider because they were really very fine and hard to solder without burning them off.

Tabwelder PCB

I used the hacked Laminator below and the Toner transfer method to make this double sided beauty. CLICK ON THE IMAGE TO SEE A FULL SIZE PHOTO. TO ZOOM IN AND OUT CLICK ON THE IMAGE,  HOLD YOUR CTRL KEY AND ROLL YOUR MOUSE WHEEL. IN CASE YOU DIDN'T KNOW THIS, YOU CAN ZOOM IN AND OUT ON WEB PAGES AND DOCUMENTS ON YOUR COMPUTER BY USING THIS TECHNIQUE.