Browse Prior Art Database

Multichannel Constant Current Supply

IP.com Disclosure Number: IPCOM000091918D
Original Publication Date: 1968-Jul-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Furois, PC: AUTHOR

Abstract

This circuit is a constant current source through a load connected at either E1 or E2 by using photon-coupled isolators 10 and 10' respectively. Complete isolation between channels is achieved. When a current flows through either light-emitting diode 12 or 12', a beam of light proportional to such current is detected by photodiodes 14 and 14' respectively. Each photodiode, in turn, conducts current in proportion to the intensity of the light beam. When a voltage is applied at terminal A of operational amplifier 20, a greater current flows through diode 12 or 12', causing a greater current to flow through photodiode 14 or 14', respectively, and resistor 30, thus raising and maintaining the potential at terminal B to the potential at terminal A.

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Multichannel Constant Current Supply

This circuit is a constant current source through a load connected at either E1 or E2 by using photon-coupled isolators 10 and 10' respectively. Complete isolation between channels is achieved. When a current flows through either light-emitting diode 12 or 12', a beam of light proportional to such current is detected by photodiodes 14 and 14' respectively. Each photodiode, in turn, conducts current in proportion to the intensity of the light beam. When a voltage is applied at terminal A of operational amplifier 20, a greater current flows through diode 12 or 12', causing a greater current to flow through photodiode 14 or 14', respectively, and resistor 30, thus raising and maintaining the potential at terminal B to the potential at terminal A. Channel 1 is completely isolated from channel 2 and the load potential at either of terminal E1 or E2 has no effect on the other. Additional channels can be attached to amplifier 20 and resistor 30. Current flow can be prevented at either output E1 or E2 by grounding terminal C or terminal D respectively, thus turning off transistor 40 and 40' respectively. A number of channels can be used with independent control over each channel by regulation at the terminals corresponding to C and D.

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