Is it possible to increase or amplify a DC current???

Question

say i have a input of 3V with a DC current of 1mA-2mA and i want to increase it to, let say 60mA or higher...if possible, can you give me a schematic diagram of the circuit...thanks..

Answer 1

You have around 6 milliwatts of power and wish to obtain 180 milliwatts. This means you must have a source with more power and regulate it down to what you wish. This is a pretty common application today with the lithium ion batteries. The following are two example circuits for your reference, using popular linear regulators:

1) 431 shunt regulator circuit:
http://www.zetex.com/3.0/appnotes/apps/an27.pdf

2) LM317 adjustable regulator circuit:
http://www.edn.com/article/CA505071.html
http://www.edn.com/contents/images/505071f1.pdf
In this case, you adjust the ratio of the R5 & R6 resistors to obtain the desired output voltage. The LM317 application note discussing this ratio is:
http://www.national.com/an/AN/AN-181.pdf
(they refer to R1 & R2).

If you have a serious application, the National LM317 is the classic device to use.

Good luck.

Answer 2

If you only need 60mA within no more than about 2 Mhz bandwidth while keeping the voltage the same at 3V, use an analog buffer. It is a unity gain opamp. Its circuit is trivial: just connect the output terminal of the opamp directly back to the negative input terminal. Depending on the opamp, typically you can only do up to 2 Mhz of bandwidth because the opamp gain drops with higher frequencies and the limited gain times bandwidth product makes this a low pass circuit.

If you need much higher current, or low current but wider bandwidth, you may want to use power FET transistors. Basically for voltage gain, use common source (common emitter in BJT). And for current gain use common gate (common base in BJT). You probably need a common source driving a common gate so that you have the high enough input impedance.

Answer 3

From just that 3 volt source, no, it is not possible. That said, if that 3 volt source is feeding the control side of a FET or transistor that is connected to a larger voltage source, then yes, it is not only possible, but is done in any of a number of electronic devices everyday.

Answer 4

The power into the circuit is volts*amps = 3 v * 0.002 a = 0.006 watts. Without adding additional power, the only way to increase amps is to decrease volts. Is this acceptable to you?