The Builder of this unit says the following about the Prototype - Left unit is the Ard**no micro for translating time to current PWM values. Right unit is a real-time-clock unit powered by a button cell battery so I don't have the set the clock every time it loses power." Like I said above, I would use a Parallax Propeller or BASIC Stamp 2 - my micro-controllers of choice!
The builder also says, "These aren't the original dials, obviously. The original ones were for displaying current in microamps. I scanned the original dial and then photoshopped these time-appropriate ones."