AMF Educational (Analog) Computer Model 775-A

There is nearly no information on this analog computer trainer. It is pretty basic with limited functions. The panel is wood and the front surface is a bit oxidized. The controls took a bit to figure out and there is literally no information on the web. 

I traced out the integrator and timer PCBs to understand their functions and calibrate them.

Integrator and Timer schematic

The Set button initializes the integrators to the Initial Condition value.

The Integrator functions only when the Integrate switch is activated (to the right).

When activated the integrator functions for the duration set by the Time Switch with Man being continuous.

I believe grounding the Remote jack simply activates the integrator in Man mode.

The Meter Output jack is a strange configuration. I made a pin plug to fit.


The circuitry is pretty basic. Everything is riveted together. What's interesting is the ground lugs of the open frame 1/4 phone jacks are not wired, but a separate 1/4" phone jack provides the 0V reference.


The cabinet frame has routing to accommodate the wiring.


Two of the pointers were broken off so I made new ones from 3/32" Plexiglas. The original is on the left and my reproduction is on the right.


Here is a simple patch generating a sine and cosine wave. The integrator time constant is fixed so the frequency is pretty slow.