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rahdirs Posted - May 22 2013 : 06:11:17 AM
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Hi ppl,

At the output of my circuit i have an opamp that gives out 12V & 10mA,but the next stage of my circuit needs 12V & 5A,how do i provide this current amplification.
I tried using buffer circuit,but it showed no improvement,
The buffer was implemented using IC 741 as voltage follower.

Regards,
rahdirs
3   L A T E S T    R E P L I E S    (Newest First)
audioguru Posted - May 29 2013 : 5:06:29 PM
The datasheets for the weak little BD243 and BD244 show that they have an absolute maximum output current of 6A when their base current is very high at 1A.

Many high power amplifiers use output transistors in parallel to provide high currents.
Use power darlington transistors for high output current but low input current.
rahdirs Posted - May 29 2013 : 05:21:56 AM
@audioguru:I also noticed this problem by studying data-sheet of IC 741 and thought of using a Class AB / Class B power amplifier to provide the necessary power gain.
The 25mA is coming from IC 741.The problem i face is my power amp is only providing 1A at the o/p as in schematic.I need 10 A is there any other way ???

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audioguru Posted - May 28 2013 : 5:45:59 PM
The maximum output current of an old 741 opamp is only 25mA.
Why do you think it can supply 5A which is 200 times more?

Any opamp can drive the zero current input of a Mosfet at DC and low frequencies.

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