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This simple throttle circuit for low power motors has quite good low throttle performance.
It uses a type TIP 141 darlington output transistor but a BD681 can be substituted. A heat sink is necessary for the transistor as it drops considerable power at slow speed. The resistors and potentiometer should be 1 watt rated. Power input can be 9 to 12 volts A.C. Designed primarily as a quick build throttle for N scale but could work on other scales.
Keep to the resistor values shown and use a heat sink.
---- Running report
Works surprisingly well on N Scale locos for such a simple throttle. Very slow starts and smooth control with a good control range. Only a small dead band. Some feedback as load increases.
This simple throttle circuit for low power motors has quite good low throttle performance.
It uses a type TIP 141 darlington output transistor but a BD681 can be substituted. A heat sink is necessary for the transistor as it drops considerable power at slow speed. The resistors and potentiometer should be 1 watt rated. Power input can be 9 to 12 volts A.C. Designed primarily as a quick build throttle for N scale but could work on other scales.
Keep to the resistor values shown and use a heat sink.
---- Running report
Works surprisingly well on N Scale locos for such a simple throttle. Very slow starts and smooth control with a good control range. Only a small dead band. Some feedback as load increases.
LINK TO IMAGE - simple-cab1.giff
Circuit Schematic
