simple current controlled led tube

Posted on Feb 6, 2014

The given circuit of a current controlled LED tube light uses a couple of high voltage transistors which works on a very basic principle for implementing the required current control operation. Resistor R2 is placed forconvertingthe rising current to voltage across itself. This voltage is sensed by R2 which immediately conducts and grounds T1s

simple current controlled led tube
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base rendering it inactive, the instantaneous processinitiatesa switching effect, producing the desired current control and safeguarding of the LEDs. Each channel consists of 50 white LEDs in series. R2 is calculated with the following formula: When input AC is applied to the circuit, C1 drops the input current down to a lower level which can be considered to be safe for operating the involved electronic circuit. As long as the current delivered by T1 or rather current drawn by the LEDs iswithinthe specified safe limit, T2 remains in a non-conducting state, however of the current drawn by the LEDsbeginsto cross the safe limit, the voltage across the limiting resistor R2 begins to develop a small voltage across it. This inhibits T1 from conducting fully and its collector current stops rising any further. Since the LEDs form the collector load of T1, the current through the LEDs also gets restricted and the devices are safeguarded from the rising current intake. Ths above rise in the current takes place when the input AC rises, producing an equivalent increase in the LED current consumption, but the inclusion of T1 and T2, ensures thatanythingthat`s dangerous to the LEDs iseffectivelycontrolled and curbed.

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