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Build Voltage controlled current source

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ze-trinchas

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Hi ppl

I need some help on a design.
I need to build a voltage controlled current source as well developed as possible.
With this i mean, my requisits are:

--- It should work with frequencies ranging from 100Hz to 20MHz
--- Presenting over that range a THD of about 60dB
--- And the output should be able to give a maximum current bettween [0.5A to 1A].

If you have ideas for this project, places where i can research, sites, components wich could easy the development, post it!!

I´m just starting the research for this, so every idea counts.

best regards
 

Hi

For staters sourcing would be enough.
I think it may simplify things right?

regards
 

Actually, it is easier to build a sinking current source ..

Here is one example based on the PICAXE-08 microcontroller and with slight modifications it can be converted to sink currents of several Amps ..

So, take a look at this example and if you have any comments please post them here ..

Regards,
IanP
 

Hi

In this case for my application i need sourcing.
The idea is to deliver current to an inductor to create specific magnetic field.

thank you

regards
 

In this case you can use LM317 voltage regulator and configure it as adjustable constant current source .. see picture below ..
More details you can find in the LM317's data sheet ..


This, of course will not be voltage-controlled-current-source, but it is a very simple alternative ..

If you need to control current by varying voltages then you will need to employ an opamp with an external PNP power transistor and the control voltage will be referenced to Vcc .. see picture below ..
The output current will be: Iout = Vz/R1 ..

Regards,
IanP
 

Hi ze-trinchas
Are you sure about the frequency and the current amplitude?
because 1A current @ 20MHz , it wont be eazy
Such power signal is used for short wave emitters !
 

Hi timo

That´s correct 20MHz.
Yes i know that, it will be very hard.
Specifically with those requisits.
I´m starting to studie how to do it, that´s why i said if someone has suggestions send them.

regards
 

I guess you should refine your requirement by a detailed description of your load.
It looks like a medical device for electrotherapy.
Classic aproach as those shows on schematic will not work too well at this frequency.

greetings,
 

Hi

The circuit load will be an inductor that will be used to generate varying magnetic field. The specific values for the inductor impedance are still in study so i don´t yet jnow them.

I know that those circuits wont work and wont perform within the requisits i presented.
If you have any directions to give, or considerations post them.~

regards
 

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