A Full and Half-Wave DC Test Throttle

Published:2013/6/25 21:59:00 Author:muriel | Keyword: Full, Half-Wave, DC Test Throttle | From:SeekIC

The next throttle is one that was put together for testing purposes only. As can be seen it is a modification of the basic transistor throttle shown above. The SPDT switch allows the throttle to have a full or half wave DC output. The value of the 8 uF capacitors is calculated to allow the voltage across the 1000 ohm potentiometer to decay to 1/3 of the supply voltage before the next cycle starts. At 120 Hz; 8 uF is needed and at 60 Hz; 16 uF is required to achieve this result. This means that the peak output voltage of the throttle has value that is three times the lowest voltage of the output for a given throttle setting. Please refer to the wave forms diagram below the schematic for clarification.If the 8 uF capacitors are omitted, the circuit becomes an overly-complicated, fullwave DC throttle. The throttle as shown has an automatic current limiting of about 2 amps and a quasi-regulated output voltage. This throttle gave pretty good results with an Atlas locomotive and one from a starter set of the type that make their appearance at Christmas time.



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