Dr. Who Dalek ring modulator

[Dmod]

Hello, I am trying to build this ring modulator on vero board.  The schematic is simple but I know nothing about transformers.  I know this may not be a guitar effect but it looks like it could be a simple layout for someone who knows how to work with transformers.  It was used to make the dalek voice effect in the doctor who series.  

I found an online auction thats says it uses these parts but it only includes an image of the schematic and the seller told me he has no further information on how to build the unit.  

"This eBay auction is for a Ring Modulator Kit. The kit contains: 2 of the Xicon 42TM018 10K to 10K Center Tapped Audio Signal Transformers, and 4 of the1N5817G Shottky Diodes (Very Low Voltage Cut-Off), Two Male RCA Connectors and Cable, and One Female RCA Connector and Cable, and hard copy of the Ring Modulator Schematic. The original Dr. Who sound effects generator."