AC Voltage to AC current converter. Urgent reply needed! Please help!

[metallica_jay]

A voltage-to-current converter that will convert the filter output voltage:
• Current output 5 to 25 mA current loop
• 5 mA for zero input to the system and 25 mA for a 5 mVrms input to the system.

My output from the OPAMP 5th order filter generates a 14mA ac Vpk voltage. It would be nice if I can have a design with an explanation without using BJT. Also I do not understand where the zero input is coming and how it can give a 5mA output.

Thank you in advance.

 

[metallica_jay]

Can someone please explain how this circuit does giving the criteria above? I can see the bridge rectifier making the AC voltage to DC but I am unsure how its giving 5mA for zero volts and 25mA for 5mVrms that is used as the input to the bridge. Please ignore 14mA I mentioned previously as I can easily make it 5mVrms by using a current divider circuit. Also what happens to forward bias 0.7v voltage drop to the diodes when I am only sending 5mVrms?

My dealine is tomorrow and any help or suggestion will be highly appreciated!

 

[wakoko79]

That is a unity gain amp, AKA buffer.
You will get a filtered DC voltage with slight ripple at the output of the bridge rectifier. I don't see how that could be a current source.
Basically, you are just buffering. No voltage to current conversion as far as I am concerned.

The ckt is also unclear. If it is wired like the anode of D1 is connected to the ground, then you are probing (voltage probe) the ground.

 

[unclejed613]

since you said at first you wanted to convert AC voltage to AC current, i was going to provide a link to my AC current source article here: https://www.electro-tech-online.com/blogs/unclejed613/121-ac-ohmmeter-revisited.html

but now you're trying to convert to a DC current? so now i'm confused.... are you using this to measure a voltage, or convert audio voltage to a current to transmit audio over a current loop (usually a phone line)?