Control for stepper motor operated call charge counter - employing two Darlington transistors to alternately charge and discharge motor circuit capacitor

摘要

The power supply (SV) voltage and current, derived from the telephone line (a,b) and also the complexity of the circuit, can be reduced by employing a Darlington transistor in the winding capacitor (C2) charge (T3,T4) and discharge (T5,T6) paths. An incoming 16kHz charge unit pulse is detected and smoothed (T1,C1), and triggers (T2) the charging circuit transistors (T3,T4). At the end of the pulse the charging circuit switches off and the discharge circuit (T5,T6) automatically conducts. Both operations in series move the stepper motor and counter (Z) forward one step. If germanium transistors are used (T4,T6) the power consumption in the steady state can be reduced further.