AC current source up to 100KHz

[alino]

Hi to all,

I need a schematic for a Constant current source up to 100KHz to use it in medical application. Can someone please helps me?

Best regards,
alino

 

[antedeluvian]

You are not specific on the current that you need, nor the impedance that you are driving.

I wrote an article on generating AC currents aimed at a high current and low frequency application. The frequency is merely a function of the magnetics so you may be able to adapt it. The article is here
**broken link removed**

In principle it is based around a transformer and the equation power in=power out. You then use a transformer with a very high turns ratio so that you get a high current of low voltage at the output. Applying a controlled voltage (of some current capability) at the input results in a controlled current current at the output. Measuring and feeding back the current to the primary's voltage will close the loop.


If you only need a small current, I daresay you could generate an AC waveform and use it to drive a Voltage to Current Converter- I would search for that phrase on National Semi's website.

-Aubrey

 

[alino]

Hi Aubrey,

Thanks for your interesting article and your support at all. I thing the source current in your article is extremly powerfull an huge comparing to what I need.

In fact I'am looking for an AC source current with a amplitude of about 10 to 20mA under a frequency between 50KHz and 100KHz. This is to measure bioimpedance (with resistance up to 10MOhms und capacity up to 100nF). Therefor the source should be stable so that amplitude should remain constant, wenn the load drop down to some Ohms.

Hope the informations are sifisant.

Best,
Alain