Silicon Controlled Rectifier. See https://en.wikipedia.org/wiki/Silicon_controlled_rectifier 3 nodes, 1 internal node 0 = anode, 1 = cathode, 2 = gate 0, 3 = variable resistor 3, 1 = diode 2, 1 = 50 ohm resistor

Silicon Controlled Rectifier. See https://en.wikipedia.org/wiki/Silicon_controlled_rectifier 3 nodes, 1 internal node 0 = anode, 1 = cathode, 2 = gate 0, 3 = variable resistor 3, 1 = diode 2, 1 = 50 ohm resistor