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US 4,288,740 AGranted
Constant current switch
AssigneeLicentia Patent-Verwaltungs-G.m.b.H.
InventorsKarl-Diether Nutz, Helmut Moser
Life of this patent
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Abstract
A constant current switch for controlling a generally constant switchable load current with fluctuating voltage comprises a first transistor connected in to the current branch of the load circuit and having a voltage divider in parallel to its control path for measuring its control voltage and a second transistor connected to the control input of the switch and to the voltage divider.
Claims4
A constant current switch for controlling a largely constant switchable load current in the case of a fluctuating supply voltage subject to large decreases, comprising:
- a first bipolar transistor connected into the current branch of the load current;
- a voltage divider for measuring the control voltage at said first transistor connected in parallel with the base-emitter path of said first transistor;
- a second bipolar transistor in connection with a control input of the circuit and having its base electrode connected to said voltage divider;
- and a third bipolar transistor connected between the collector electrode of said second transistor and the base electrode of said first transistor, with the collector electrode of said second transistor connected to the base electrode of said third transistor and the emitter electrode of said third transistor connected to said voltage divider and to the base electrode of said first transistor.
1 more element
Dependencies are inferred from the claim text.