Help with >2W sine wave using LM1875T or other


I am attempting to take a sine wave signal between 1Vpp - 5Vpp (using a digipot/pot for variable gain) and amplify the current to a wattage of 2W or greater. It will be used to drive a resonance LC circuit.

I previously tried to build a non-inverting TL082IP circuit attached to a Class AB amplifier but I couldn’t get the current above 140mA.

I then tried a TDA2030a but I think the component I had was not authentic. I am now using a LM1875T but having trouble making negative voltages lower than -15V (using a ICL7660s and NE555P) and need lower than -20V.

Does anybody recommend how to make -20V rails or another component than the LM1875T to achieve a variable sine wave amplification of 2W or greater between voltages of 1Vpp - 5Vpp?

Thank you for your time.

Welcome to the Tech Forum! I am looking to see what I can find out for you.

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Thank you for taking the time!

Simple amplification at these levels should be a relatively straightforward matter; I suspect that there are some component limitations involved that have not been fully appreciated.

A more thorough description of the circuit(s) in use and the objectives would be helpful; schematics are worth a thousand words. Among other things, I’m finding no mention of the intended power source for the apparatus.

7660 charge pumps are neat little devices, but process a minor fraction of a watt at best. To get two watts out, at least two must go in.

The vast majority of power supplies fed by AC utility power have isolated outputs; those that do can be used to create either “positive” or “negative” output voltages simply by deciding which output lead to label as the zero-volt reference point. If one’s trying to operate from a few AA batteries though, that’s probably not going to do the trick.

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