Variable AC Fan Controller 

Variable fan voltage 120v input  ~0 to 145v output ~1A rating

Transformer is 120v input - 25.2v 2A output Radio Shack 273-15128

600w $4 light dimmer works fine

Mounted in standard 4-gang construction box.

One side of transformer has two black leads, designed for ac in. The other side three leads, has two yellow leads with black in-between. Cap off center black lead, not used. (just seen below #3)

#1 shows incoming ac black, transformer left incoming black & output yellow left wired together. These WILL NOT be directly connected to output, it's the boost feeding 1/2 transformer output back.

#2 shows ac in white and the right side transformer input black connected plug.

#3 shows right side yellow transformer lead connected to dimmer input. (If not using dimmer, would connect directly at #4 for constant boosted voltage)

#4 shows dimmer out going to other side of plug. (note, it doesn't matter which dimmer lead is used for in or out, just so one is in and the other out! The dimmer simply *breaks* one side of the ac loop, same as a switch.)

Note: greens wires are ground from ac in and dimmer ground lead connected to plug ground. Transformer does not have ground lead....

Hope this helps aspiring home roaster control builders!

Shows max load voltage driving Caffe' Rosto fan. (Note, roasting station fed with 12 gauge 25 foot extension cord.)

Shows minimum load voltage. (less than I ever use roasting.)

Any questions feel free to email me: mcKona@comcast.net

Here is a circuit schematic drawn by Stephen Rouse added by request and with permission.