Maker Factory ELECTRONICS EXPERIMENTS BOX Manual page 291

Circuit 120: FET transistor T1 acts as a variable resistor and forms a voltage divider together with R2. The
ratio and thus the degree of damping is adjusted by means of the control voltage.
Circuit 121 and 122: Activating Tab on turns on T2 and T3. LED1 is lit. A holding current flows through R3 to
the base of T2. The state is preserved even though Tab on is no longer activated. Activating Tab off turns on
T1 and blocks T2 and T3one after the other, thus LED1 turns off. Also this state is stable und preserved, if Tab
off is no longer activated.
Fig. 3.120: Circuit 120: Electronic level control
Fig. 3.121: Cir-
cuit 121: Sensor
toggle switch
with LED
293