Opisometer Geology Relay-based NAND-gate module on a

Relay-based NAND-gate module on a demonstration base

sized to read one step up from the 0-1A meter when student circuits draw past the lower meter's full-scale deflection

sized for beginner circuit and physics labs

driving performance with motor-generator #2

this concave glass mirror at 100mm focal length runs at f/1 for vivid real-image demos and converging-reflection work

Opisometer Geology Relay-based NAND-gate module on aOpisometer with a knurled wheel on a threaded spindle, rolling along curved lines on maps, charts, and drawings to convert winding distance into straight line length for geography coursework.