Companion plotter

Two common output devices for an analog computer are an oscilloscope and a plotter. I picked up a 80's era HP 7015B XY plotter on eBay to go with the TR-20. It was filthy and the white surface was peeling up when I got it. I dismantled it and cleaned everything thoroughly. A bit of glue fixed the paper grip surface.

The white surface has a grid under it with 900 volts DC on it. When activated, it creates a charge the pulls the paper down and holds it in place.

The TR-20 I own originally came with a 4 channel XY scope. It even has the module to feed signals to the scope and the connector on the back for it. I doubt if many of these have survived. I may try to find a good use 4-channel scope to recreate that functionality later on. For now, my simple 2-channel Tektronix scope should work just fine.