Filter Capacitor Dischargers Save Energy
Increase your power supply efficiency by using a QBAR® switch to lower the parasitic current drain through the bleeder resistor during normal supply operations. Ordinarily, selecting a bleeder resistor is a trade-off between power waste and satisfactory discharge time. A QBAR® switch - OFF during normal operations- is turned ON at supply turn-off and stays ON when all voltages fall to zero.
QBAR® switch bleeder for transformer supplies:

 

QBAR® switched bleeder for off-line supplies:
a.c line voltage R1 R2 QBAR Switch
120 V (40 V to 132 V) 470 K 1 K QB312-A
220 V (80 V to 264 V) 1 M 4 K QB312-B


Application Hints:
Prevent over-voltage damage from inductive kick-back with a signal or rectifier diode. or a zener diode.

 

Limit incandescent lamp in-rush current. Snubber network reduces interference from load and switch transients.


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