| Electronics > Beginners |
| Audio Amplifier |
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| staticshock:
It's been awhile and I may have forgotten some information, but any information provided should sort of point me in the right direction. I need some help on designing an audio amplifier for voice. I'm going to have a 7Vrms input that needs to output one 10Vrms and three 3Vrms. I'm assuming I'll need to amplify the 7V to 10V and perhaps a voltage divider to get the 3V. I've attached a diagram of what the circuit should look like roughly. I'm a bit confused or just may be thinking too hard on how to achieve my objective. |
| soldar:
When dealing with voice you are better off specifying peak to peak because RMS is not a fixed value like it is for a sine wave signal. |
| Zero999:
You haven't provided enough information: what are the input and output impedances? Does it need to be Hi-Fi or just telephone quality? |
| staticshock:
The input and output impedance aren't specified. There is really no restrictions to the design. I believe the voice audio is over a radio system so I guess telephone quality. |
| Zero999:
A potential divider can be used to reduce the voltage. If the output impedance is too high, simply connect a unity gain op-amp circuit to the output. The calculator, linked below, can be used to calculate the resistor values. Use the E24 resistor sequence if you just want cheap, commonly available resistor values. http://www.ti.com/download/kbase/volt/volt_div3.htm A non-inverting op-amp configuration can be used to amplify 7V to 10V. https://www.google.com/search?client=firefox-b-d&q=on-inverting+op-amp The calculator linked to previously can be also used to calculate the resistor values for the non-inverting op-amp, but where it says "output" enter the input voltage and where it says "input" enter the output voltage. This is because a non-inverting amplifier is just an op-amp connected to a potential divider, so it works in reverse. This is the magic of negative feedback: the op-amp does what it can to keep its inputs at the same voltage. |
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