[PIC] how can i use zener diode in place of optocoupler?

[jigar@19021993]

i want to use zener diode in place of optocoupler for saving space... i m using transistor(NPN) and zener diode before transistor. i also pullup supply by 5 v. so is ground makes transistor on?

https://obrazki.elektroda.pl/7065010000_1391513942.png
this is image of conection i m making.

 

[barry]

The only thing a zener and an optocoupler have in common is that they both have "er" in them. Why do you have a zener in your circuit? Why do you have that other diode? Why do you have two 10Ks in series with that zener that you don't need? What is it you actually are trying to accomplish?

 

[FvM]

so is ground makes transistor on?

I understand that you are asking if pulling the input to ground turns the transistor on? No, it will turn it off.

On optocoupler would be used if isolation between different circuit grounds is required. So it's not clear why anyone had considered an optocoupler in this place. If you want signal inversion, use a second transistor, or no transistor at all.

 

[ADGAN]

Zener diodes can be used for protection. In other words it regulates the voltage. But as FVM has mentioned optocoupler's are used for isolation. Use of opto-coupler would not be necessary for your application. Also I think the way you have used the Zener diode is incorrect. Why have you used a diode and two 10K for pull ups ? only one would be sufficient.

 

[Analog Ground]

Zeners can also be used for level shifting but I don't see how that would apply to this circuit the way it is configured.