I would like to make a microphone preamplifier for my phone. I need to emphasis that I am a newbie and I have never finish an electronic project by myself. So Please give me some help! Thank you in advance.
I have find some information from internet and the preamplifier based on the IC–LM348 I think is more suitable for me. According to the datasheet of LM3480, it is an intetrated linear voltage regulator while it can use in tiny alternative.
However,I have never done such a project. I really don’t know how to do it at all ? Are there anyone do such a project? Could you give me some suggestion and show me the feasible circuit ?
Thanks a lot !
First of all, why do you need it ? the phone microphone input is made to be used with passive, non-preamplified microphone
If you still need to do it, i don’t really understand the need the the LM3480 Voltage regulator, to which i can’t find any use in a pre-amplifier.
You need to use a circuit based on an AOP, a non-inversing amplifier circuit, its a really simple and cheap circuit
R1 and R2 are defining your gain, so i suggest you to use a potentiometer so you can adjust your gain.
You have to plug your microphone on Ve, and the AOP needs to be supplied in +5/-5V at least.
You may also need to add a high pass filter (100Hz) on your input, just use a capacitor and a resistor :
for your AOP, check your local electronic store
And, most of all : DON’T test it on your fairphone, you could fry it…the mic input is designed to receive very small signal, 200mV peak !, check your circuit output with a DC input and and a voltmeter, to verify your gain.
I’m still quitly skeptical about the need of a preamp…are you sure of what you are doing ?
I would use a USB-OTG microphone.
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