[PIC] Optocoupler as an input to mcu to test line current ?

[burrow]

Hai,
iam doing a project using pic18f4520.
And mcu requires an input to test if an AC 240V line is alive. Iam planning to use optocoupler for that purpose. I have MCT2E optocoupler. Please help me with the connection. how am i supposed to connect ac lines to opto and how opto should be connected to mcu ?

 

[Easyrider83]

Emitter to ground, collector to pull-up resistor and directly to pin. If week pull up (wpu) option available, you may use it without external resistor.
To light the optocouple use ~200v zenner diode and resistor.

 

[burrow]

Emitter to ground, collector to pull-up resistor and directly to pin. If week pull up (wpu) option available, you may use it without external resistor.
To light the optocouple use ~200v zenner diode and resistor.

Okay.. thanks for the reply buddy. i have attatched an image. is the circuit right ?. But it doesnt seem to

 

[Easyrider83]

Absolutly not. AC line should be isolated. 200V will drop on diode, last 20V should provide 5mA current to light the optocouple. So, the resistor should be 20/0.005 = ~4k or 3k7 from standart table.

 

[burrow]

Absolutly not. AC line should be isolated. 200V will drop on diode, last 20V should provide 5mA current to light the optocouple. So, the resistor should be 20/0.005 = ~4k or 3k7 from standart table.

it would be glad if you can show me a demo circuit.

 

[Easyrider83]

You can take this schematic:
**broken link removed**
But use only left part till R3. Capacitor will limit the current.

 

[burrow]

You can take this schematic:
**broken link removed**
But use only left part till R3. Capacitor will limit the current.

Thanks .

 

[Easyrider83]

Should I tell you that all values must be calculated for your optocouple?