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Regulated Transformerless Power Supply

IP.com Disclosure Number: IPCOM000081980D
Original Publication Date: 1974-Sep-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Atwood, LW: AUTHOR [+3]

Abstract

This power supply uses cascaded sections of capacitive series voltage dividers in series to reduce and store full-wave rectified DC input voltage, which is then discharged in parallel at the desired output level. The charging and discharging of the cascaded capacitive series is regulated by a switching network driven by a feedback voltage derived from the output, to regulate the charging of the capacitors in series and the discharge of them in parallel.

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Regulated Transformerless Power Supply

This power supply uses cascaded sections of capacitive series voltage dividers in series to reduce and store full-wave rectified DC input voltage, which is then discharged in parallel at the desired output level. The charging and discharging of the cascaded capacitive series is regulated by a switching network driven by a feedback voltage derived from the output, to regulate the charging of the capacitors in series and the discharge of them in parallel.

AC voltage 1 is rectified in a diode rectifier bridge 2 and applied across capacitor 3, to form an unregulated DC supply at a full-wave rectified voltage of approximately one-half the AC line voltage supply. The rectified direct current is applied to transistor switch 4, which may be alternately closed and opened using the output from an astable multivibrator 5.

When switch 4 is closed, pulsating direct current is fed into the divide-by-two network 6 where the voltage is cut in half, due to the fact that the diodes used force charging in series of the capacitor used. The power is then applied to another transistor switch 7, similarly under the control of multivibrator 5. The output from transistor switch 7 is applied to yet another divide-by-two network 8, where the final output voltage is produced which is fed to load 9.

The output voltage is sampled in a resistive or capacitive voltage pick-off 10, and the sample voltage sensed is then compared in a differential amplifier 1...