Here the simple mic pre-amp circuit design based on single IC LM358. The circuit is very simple, inexpensive and easy to built. This mic pre-amplifier circuit operated with 9V DC voltage, you may use 9V battery for this circuit.
Component Parts List:
R1, R3, R4 = 10K
R2 = 1K
R5 = 100K-1M Potensiometer
C1 = 0.1uF
C2 = 4.7uF/16V
IC1 = LM358 dual op-amp single supply
Mic = Electret Microphone
Notes:
- Use R5 to adjust the gain of op-amp LM358.
- The LM358 has dual op-amp module, you may build stereo audio pre-amp using single LM358. These devices consist of two independent, high-gain frequency-compensated operational amplifiers designed to operate from a single supply over a wide range of voltages.
Download PDF document of LM358 datasheet from below link:
The simple mic pre-Amp based LM358 circuit designed by Tony van Roon
The out put will go to the next stage which is full powerful amplifier, as the circuit is PreAmplifier.
You can use power supply less than 9V I would expect it to work fine, no need to change any resistors or capacitors value, but capacitors should be bit higher than 9V
what will be better lm358 or lm386 as i want the input from the microphone to be given to micro-controller
I rebuilt my circuit this morning and got better results. The oscillations are now proper. I do still have a DC offset, but I guess something like a speaker will only catch the alternating signals any way (I ditched the resistor I had added to the output cap).
I tried building this for my guitar as a test. My output from C2 before I hooked the guitar up was floating around 3.7V, so I grounded it with a 100k resistor (high-pass filter). Is this normal, or did I hook something up wrong? Also, I only seem to be getting voltages above the output, isn’t the point of the voltage divider on pin 3 to allow signals to oscillate around 2.5V up AND down?
thanks for help
hello
i want amplify the weak audio signal. in your point of view which of this op-amp suitable:
lm358 vs 741?
Q1: Yes, this work with 5V supply. LM358 has a wide rang voltage supply of 3V to 32V. You may try to lower the R1 value.
Q2: The output will be to the mixer circuit, echo chamber, or directly to the tone control circuit.
Hi,
Q1. You have a power supply of 9V in the circuit. Will this circuit work if I have a 5 V supply? If it can, then obviously the values of the capacitors and the resistors would change. Are there any rules or equations that I may need to calculate the values of components if I have a 5 V supply?
Q2. Where does the output of the system go to?