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How Can I connect a Bi Color LED to a Relay interfacing circuit ?

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milan.rajik

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How Can I connect a Bi Color LED to a Relay interfacing circuit ?

The LED is 3 pin type. LED rating required is 10 mA, 2.1V. The relay is driven by a opto and BC337. Opto's output collector is connected to 5V and emitter is connected to a Voltage divider which divides the voltage to 4.2V and 0.8V. The 0.8 V biases the BC337 BE junction. The LED has to turn RED when opto is not ON and Green LED should turn when Opto is ON.
 

You can do in this way

Opto off ,Red LED ON
Off.png

Opto on ,Green LED ON
On.png
 

It depends on whether your LED shares a common anode or common cathode.

The simplest scenario is you connect the LEDs to spare contacts on the relay. If the LED is common anode, you could connect the common pin to the relay supply, one cathode through it's resistor to the collector of the transistor (so it is across the relay coil) and the other to the collector of another transistor with it's emitter grounded and base fed through a resistor from the collector of the existing transistor so it makes an inverter.

Brian.
 

The relay is 1 Form A type T9AS1D12-5 tyco 5V relay. I can't connect LED to Relay's output side. It is a 230V 30A relay (Output contacts). I need input side circuit of relay to toggle the RG LED.
 

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