Sorry for asking a non-keil related question. I have a microcontroller that generates some noise by a PWM signal / speaker. I use three NPN transistors as audio boosters. My power source is momentarily a power supply of 9V 750mA (will be batteries on the end). Can you recommend a way to boost the volume and to generate very high frequency sounds? Is there an advantage to use an audio amplifier rather than NPN transistors if I don't care about sound quality?
Consider using an audio transformer, it's what they are designed for. They simplify matching the speaker impedance, block any DC, isolate the circuit 0v from the speaker -ve.
Thanks for your reply. I am indeed using a square wave. The three NPNs are connected emitter to base - that arrangement seems to work fine. I am using a simple 8 ohm speaker. Can you recommend a specific bridge IC?
How are you using PWM? If you just want a noise, wouldn't just a square wave be adequate?
How are you using the 3 NPN transistors? What kind of audio output transducer are you using?
For maximum amplitude, use "bipolar" drive - like a bridged audio amp.
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