Browse Prior Art Database

Power Supply Turn-On Circuit for Remote Stations

IP.com Disclosure Number: IPCOM000036623D
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Kantner, RF: AUTHOR [+3]

Abstract

A technique is described whereby a power supply turn-on circuit allows an internal power supply of remote stations to be turned on or off, only when a master unit is turned on or off. The circuit is applicable to remote units, such as workstations, printers, etc., which use the same AC power lines as the master unit. It functions by utilizing the small current flow which occurs in the neutral line of the AC power line, sensing when a master unit is energized.

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Power Supply Turn-On Circuit for Remote Stations

A technique is described whereby a power supply turn-on circuit allows an internal power supply of remote stations to be turned on or off, only when a master unit is turned on or off. The circuit is applicable to remote units, such as workstations, printers, etc., which use the same AC power lines as the master unit. It functions by utilizing the small current flow which occurs in the neutral line of the AC power line, sensing when a master unit is energized.

The circuit is unique in that it requires no external voltage to activate its circuits. It derives its power by sensing the current flow in the neutral side of an AC line of interconnecting units. The circuit, as shown in the figure, is installed in a remote unit, utilizing the return current of the neutral AC line. The return current flows across back to back zener diodes 10 generating approximately 3 volts across the diodes when the master unit is turned on. This current is rectified by diode bridge 11, so as to supply DC power to the rest of the circuit.

Resistor 12 is positioned across diodes 10 to shunt any small leakage current and to prevent the circuit from being falsely triggered by the low current. This is done by keeping the voltage to a level lower than the 2.5 volt threshold required to energize relay 13.

When the master unit is turned on, approximately 300 to 500 MA will flow through diodes 10 to produce 3 volts. The actual amount depends on the ...