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Digitally Controlled Current Source for signals - Need help

efelnavarro09

Jan 18, 2011
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Jan 18, 2011
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I started working on a function generator that gives ouput of different waveforms, such as: sine, sine half wave, sine full rectified, square, triangle, saw tooth, biphasic square, etc. with a constant output of 30Vpp. My question is about how dow I need to handle this signal in order to vary its ouput current in a range of 1mA up to 150mA with a variable Rload in a range of 500Ω up to 10KΩ so the output current must stay "constant" within this range. I need to be able of change the output current digitally, maybe using a DAC, Variable gain opamp...

I have been looking and some theory and circuits about Voltage to Current Converter with grounded and floated load, Current Mirror. But I still don't fully understand how do I need to "connect" the constructed signal into the current block prior to connect it to the RLoad. Since all the examples I found in books, google, connect the respective outputs to a fixed source such as V+ instead of a variable one (maybe AC).

So any idea, further information, example is highly appreciated. Thanks in advance.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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if the current through a load resistance remains constant, the voltage across it is likewise constant.

You can have a voltage source, or a current source. It can't be both.
 

efelnavarro09

Jan 18, 2011
2
Joined
Jan 18, 2011
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Hello, thanks for your reply. Finally if figure it out how to solve it, may be is no the best way but at the moment it works for my application. Y decided to make a "digital" selector using transistors with different resistance values, i take as an example an application of the L200 voltage regulator. I don't have a very smooth lineal control but for the momment its ok. Thanks.
 
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