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Circuits to Adjust Current to Match Requirement of Loads

IP.com Disclosure Number: IPCOM000092496D
Original Publication Date: 1966-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Newsom, HM: AUTHOR

Abstract

The circuits adjust the effective value of current applied to match the current requirements of the load, such as a lamp of a projector. Thus the load can be operated on either 115 volts, 60 cycle AC or 12 volts DC.

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Circuits to Adjust Current to Match Requirement of Loads

The circuits adjust the effective value of current applied to match the current requirements of the load, such as a lamp of a projector. Thus the load can be operated on either 115 volts, 60 cycle AC or 12 volts DC.

The circuit of drawing 1 comprises a full-wave bridge rectifier CR1... CR4 connected in series with silicon controlled rectifier SCR and the load, a lamp of a projector. Resistor-capacitor circuit R1C1 is connected in parallel with the anode-cathode of SCR and triggers the gate of SCR which is connected in parallel with R1. When the voltage source is DC, C1 charges through R1 to a voltage such that the SCR gate triggers SCR. With this condition, the full-wave bridge rectifier provides current flow through the SCR anode, cathode and load. The load current I depends primarily on the load resistance since the voltage drops across the bridge rectifier and the SCR are slight. Conversely, when the voltage source is AC, C1 starts charging through R1 each half-cycle. Depending upon the time constant values of R1 and C1, SCR is triggered at some later point in the half-cycle.

R1 and C1 are chosen so that the effective load current I is equal to the I with a DC voltage source.

In drawing 2, two SCR's are utilized so that the full-wave bridge rectifier is not required. With a DC voltage source, current flow is either through SCR1 or SCR2 depending upon the polarity of the DC source. With an AC source, C1 s...