I looked up a bit of SCR info to see how to wire Karls SCR's to act as rectifiers. I'm posting this to confirm or correct me if I'm wrong. Many diagrams I saw show an AC supply, a load, and the SCR to vary the power to the load. They used a variable resistor to control power to the gate to fire the SCR sooner or later in the rising + portion of the sin wave. If Karl wired his gate to the anode with a diode (1N4004 maybe?)it should allow forward voltage to the SCR gate and prevent reverse power if there is an internal resistor present (Per SCR tutorial provided in the "Power Supply" posts). This should turn on the SCR a soon a voltage was high enough on the gate, Vf of the 1N4004 + SCR gate turn on voltage (~4V).
So, if I'm thinking about this correctly, if Karl connects the Anode of a1N4004 diode to the anode of his SCR and connects the gate to the cathode of the 1N4004 diode, the SCR should work like a rectifier. Correct?
I would recommend wiring it up this way and then powering it from a lower voltage transformer through a current limiting resistor (or light bulb) to verify everything is working as hoped. Maybe power it from a wal wart with AC output, then maybe 120V line cord with fuse, then the 230VAC mains. Just be careful, 230VAC rectified to DC with capacitors charging to peak is nothing you want to get zapped by! It's nothing to be terrified of, I work with 480VAC mains rectified and filtered almost daily, but I don't take a chance on touching it.