trying to make voltage to current converter

[sudiipta]

View attachment Volt to current.docHi, I am attaching a image for volt to current converter. I found it on some old thread here only.It looks like howland circuit with push-pull amplifier. My question: opamp o/p going to base of transistors. Emitter are shorted and we take output from there. Whether 390 ohm resistor which is actually connecting both base and emitters are correct in the diagram?

Here is my image URL or see the attached doc file

https://obrazki.elektroda.pl/64_1342748551.png
https://obrazki.elektroda.pl/64_1342748551_thumb.png

Thanks in advanced..I desperately need to build a bidirectional current source independent of load resistance.

 

[godfreyl]

The circuit looks correct. The 390 Ohm resistor is a good idea - it's to help with zero crossing.

R4 is not needed - it won't make any difference if you take it out.

 

[sudiipta]

If I add diode for crossover distortion as in class AB amplifiers, then that 390 ohm cab be removed as shown in the image ?

https://obrazki.elektroda.pl/43_1342758980.png

 

[godfreyl]

You can do that if you're careful to match the diodes and transistors. You may have to use emitter resistor as well.

I prefer the circuit in post 1. It's simpler and allows higher output current.

 

[sudiipta]

Thank you..I will try it out and update

- - - Updated - - -

Thank you..I will try it out and update