This is a 3 pen paper & ink chart recorder which has been modified by Electroprops to simulate a polygraph (or seismograph). In use, the roll-fed paper feeds forwards at a uniform speed & the 3 different coloured pens can be made to twitch by tapping on the pressure sensitive pads on the wired blue box controller visible in the third picture. It's actually very easy to use as increasing pressure produces longer sweeps of the pens. We supply wires & pads for taping to the subject that in real life would be detecting the varying galvanic skin resistance. It's sufficiently easy to set up & use that it's a completely user operated & highly visual prop. The pen mechanism is very open so you can get the camera really close to the paper & view the oscillating pen motion directly as it draws traces on the paper. We can also rig this to display other changing voltages such as those produced by muscle signals or various electronic sources.
See this video clip:
Prop ID: 1645