zero crossing detector -having grounding problem

[rutvik1588]

guys i've made a very simple zero crossing detector which gives a pluse on exact zero cross. i've simulated the ckt using multisim and it's perfectly runs. but when m going to implement the hardware m facing a problem with grounding.here m attaching d circuit and please tell me how can i make dat ground for both AC and DC. here the 5 v dc source is derived from the same AC source. And the AC voltage is directly fed through the secondary windings of step down tramsformer.
the output from the op-amp is square wave which is given to the xor gate directly and delayed which gives the pulse on Zero corssing.

 

[IanP]

Feed voltage to R4 in similar way as it is shown on the attached picture ..
This configuration creates only one GND, as it is defined after the rectifying bridge, not before ..

IanP

 

[rutvik1588]

thank u Mr. IAnP but in this manner i'll get only positive half cycle insted of full swing.i need full swing as it will trigger the op-amp to positive saturation and groud as it is an open loop configuration.

 

[keith1200rs]

You need to show your power supply circuit so people can help.

Keith.

 

[rutvik1588]

ok here i am attaching entire circuit......

 

[karesz]

Hali,
In that case is your D4 shorted :-(...
K.

 

[IanP]

Take a look at the attached picture ..
The modifications are in-line with what I suggested before ..

In this application the opamp works as a comparator, and the LM741 is not the best choice for 5V operation ..
Try LM358 ..

IanP

 

[AStar]

**broken link removed**

 

[rutvik1588]

thanks a ton Mr. IAnP