High Power Voltage Controlled Current source

[ronakv]

Hi,

I would like to design high power precision current source.
I found an Op-Amp with power MOSFET transistor are good for this design,

I have to type signals:
1- 0 to 5Volts variable amplitude pulse
2- 0 to 5Volts variable amplitude full rectified sine wave.

When I apply pulse to current source, it works good. But on the full rectified sine wave I have problem and my signal has crashed and I can't find it.

Please let me know what is the problem?
Please let me know what do you think and do you have another current source configuration?


I'm waiting to your reply.

Thanks in Advance,
Ronak

 

[MikeMl]

Welcome,

Did you post a diagram that hasn't made it through the moderation que? If not post a schematic.

 

[KeepItSimpleStupid]

Power requires knowing V and I or compliance V and I.

 

[ronakv]

circuit diagram

Hi,

I use lm324 op-amp and feed signal to non-inverting input.
Inverting input gets feedback to source of IRF640 power mosfet and source connected to GND with 10 Ohm resistor.

Please keep in your mind gate connected to output of LM324 and drain connected to transformer and other input of transformer connected to VCC=12Volts.

Please help me.

Regards

 

[crutschow]

What transformer?

Need a schematic to help you.

 

[4pyros]

ronake; Thare is no better way of knowing what you are doing than with a circuit diagram. Can you post one?

 

[Shyamal]

Need a schematic diagram.

 

[ronakv]

Hi,

This is my schematic.
" "" I WANT TO CONVERT VOLTAGE TO CURRENT AND FEED IT TO TRANSFORMER TO CHANGE LEVEL"""
My circuit on PULSE INPUT works good but I can't use it for sine wave(Full Rectified with 100Hz )

Please let me know your opinion.
Help me, please.

Regards,
Ronak

 

[MikeMl]

The non-inverting input pin 3 of the U1A cannot be driven below ground without blowing it up! R1 is likely to0 high in value (the max current is limited to less than 1A). The slew-rate of the LM324 is too whimpy to generate a 10V 100KHz pulse at either pin 1 or pin 7.

Read this previous thread.

 

[ronakv]

Hi MikeMl

At first Thanks to your reply.

Is this voltage to current converter suitable for me?
Do you know about it?
If I change my resistor to1 Ohm and change LM324 with OP07, dose it work?

in pulse mode my maximum frequency it about 400Hz!!! Sorry, in schematic I take it wrong.
I'm waiting to your reply.

Best Regards,
Ronak

 

[ronv]

What are the voltage levels of you pulse and sine wave?

 

[ronakv]

Hi,
My sine and pulse waves varies from 0 to 5 Volts and I need 0 to 70 Volts on output of transformer with 1KOhm load resistor.

Regards,
Ronak

 

[crutschow]

Why are you driving the transformer with a constant current source?

 

[ronakv]

Hi,

My load is variable and if I drive it with constant voltage mode after a period my current goes up!!!

IN CONSTANT CURRENT MODE ===> R decrease , I Constant ===> V decrease.

This mode is used on TENS stimulator.
This is my final thesis.

Thanks in Advance,
Regards,
Ronak

 

[ronv]

Strange circuit but...... Try 1/2 wave rectifier instead of full wave, then it will be more like your pulse.