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TL071 MOSFET Audio Amplifier    g eneral description:       This simple mosfet power audio amplifier circuit, with TL071 and 2 mosfets (IRF9530, IRF530) power amplifiers can deliver up to 45W on 8 ohm. This schematic is based on Siliconix application and is based on variations of voltage on the 2 resistors serial inserted on the voltage supplier of the operational amplifier driver.  The mosfet transistors must be mounted on a heatsink at least 1K/W.   Amplifier efficiency is 70%, distortions at cut frequency were at most 0.2% at 20Hz on 8 ohm and 10W. With a power supply of +/- 30V the mosfet audio amplifier can deliver 45W on 8 ohm and 70w on 4 ohm. Remember that this audio amplifier is not protected on short circuits so every time you switch on check to see if the speaker is connected. MOSFET Audio Amplifier    Circuit diagram:

In many circuits, it is necessary to use MOSFETs for switching. In many cases, the MOSFET drive signals are generated by microcontrollers. In other cases, they are generated by ICs – PWM controllers, timers or any IC in fact. However, MOSFETs cannot always just be connected to the drive signal and be expected to work properly. Due to the construction of the MOSFET, driving it is not the simplest of tasks, especially for beginners. There are many users who regularly ask for help on MOSFET drive related issues or problems on different blogs, websites and forums. So, here I will show some MOSFET drive techniques/methods for MOSFETs configured as low-side switches. Before I head on to MOSFET drive, let me just tell you what a low-side switch is, in case you don't know. When the MOSFET (that you're using as a switch) sinks current, it is a low-side switch. The load will be between the drain and +V supply. The source will be connected to ground. Gate will be driven with respect to gr...