The Power Supply

 I cleaned up the powersupply. Its a basic voltage doubler circuit with SCRs to regulate the amount of power.

The supply installed.

 The modified microwave oven transformer. I just left the primary winding, and used a piece of plexiglass as a shim to create an air gap. (This is mounted upside-down in the power supply above)

The SCR controller was broken into 2 parts, 1 circuit for user control and another to actually drive the SCRs. The two circuits are linked using fiber optics.

The schematic above is the user control. It has an AC input to detect the zero crossing. On every zero crossing the 555 timer is triggered The POT adjusts the duration of the output.  

I ran into a problem with the fiber optic recievers that I picked. The reciever is intended for high bandwidth applications (15 MB/s). To maintain a good signal to noise ratio, this reciever has a minimum bandwidth of 0.1 MB/s. The 60Hz signal I'm trying to send is way too slow for the reciever.  

Rather than spending $7.00 each for a reciever that is capable of recieving down to DC. I used a 4MHz oscillator AND'd with my firing command to generate 4 MHz bursts to get the necessary bandwidth.  

Here is the schematic for the SCR driver. The 4MHz signal is put through a lowpass filter and into a 555 timer. The 555 timer generates a pulse train that is sent to the SCRs. The frequency and duty cycle can be adjusted to match the requirments of different SCRs.

In theory, the SCR should only need a single pulse to turn on. However, when driving inductive loads, its possible the SCR could miss the single pulse.  

The SCR test setup.  

After I worked out the bugs on the breadboard, I laid the circuit out and used the school's PCB router to make some nice PCBs.  

The finished PCBs  

All of the components installed