I am new to arduino and other electronic things, I want to try to control two lights on my room using it, I made this a sketch oh how I think the circuit would go, can someone with more experience tell me if it's going to work? or if there is any component I need to add?

Here is the sketch: enter image description here

Apologies for not posting a schematic, as I said this is my first project ever on electronics. This was the schematic that was generated, I hope it's good.enter image description here About the microphone problem, the one I was intending on using would be one from my old headset, thought it would work, would it be hard to make an amplifier?

Also wanted to add just one more question if it's okay, if I want to add to the project a speaker and a sd card reader I would not have enough pins for it, is there a way to get more pins? maybe using and IC?


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    \$\begingroup\$ Please post a schematic. A Fritzing cartoon doesn't count as a schematic. Nobody should chase the wires around just to figure out what you are trying to do. \$\endgroup\$ Jun 13, 2017 at 23:03
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    \$\begingroup\$ Seems ok. Illustrations are frowned upon here, (clear) schematics are welcome. Maybe this is more suited on Arduino.SE. \$\endgroup\$
    – Wesley Lee
    Jun 13, 2017 at 23:03
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    \$\begingroup\$ Doesn't an electret microphone usually require some support circuitry to be suitable as input to an ADC? \$\endgroup\$
    – vicatcu
    Jun 13, 2017 at 23:40
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    \$\begingroup\$ -1 for the crappy Fritzing cartoon. \$\endgroup\$
    – DerStrom8
    Jun 14, 2017 at 0:49
  • \$\begingroup\$ Apologies for the Fritzing cartoon, I added the generated schematic I hope it's good one. \$\endgroup\$
    – Matthew
    Jun 14, 2017 at 10:20

2 Answers 2


Your drawing looks basically correct but your microphone circuit will likely require a bias (power supply) connection. You should pick a microphone with a built in amplifier so that it outputs sufficient voltage to be detectable with your ADC.


You've generally got the right idea, but as one commenter noted, your microphone may pose problems, depending on what type you're using.

Classic dynamic microphones (think of stage vocal mics — the Shure SM58, for example — generated plenty of electricity on their own, and don't require any built-in amplification. If you plan on using a dynamic microphone, your circuit should work (more or less — read on).

However, electret microphones — which are very popular due to their low cost and small size — have an internal FET amplifier that must be biased externally, like this:

enter image description here

Typically, a 2.2 kOhm resistor is used, and a very large capacitor (the larger, the better the bass response — 1 uF is a good starting value).

This will get you a valid signal into your Arduino, but unless you are working with very loud sounds, and don't need much ADC resolution, you'll almost certainly have to amplify the microphone first.

When you get a bit more comfortable with electronics, this is something you should try building yourself (and make sure to come back to Electronics.SE for advice!) but if you're just getting started, I would recommend using one of the many microphone break-out boards that have built-in amplifiers. This is not a shopping site, but if you search eBay/Amazon/Adafruit for "Arduino microphone" suitable products will pop right up.

  • \$\begingroup\$ I edited the post with the schematic. Would it be hard to make a normal microphone work? \$\endgroup\$
    – Matthew
    Jun 14, 2017 at 10:21
  • \$\begingroup\$ it's not too difficult. A LM386 audio amp, plus a resistor divider for DC bias should be good enough \$\endgroup\$
    – Makoto
    Aug 15, 2017 at 9:41
  • \$\begingroup\$ What is a "normal" microphone? The schematic symbol you're using for a microphone is an "electret condenser" type I mentioned in my answer (notice the "capacitor" inside your microphone schematic symbol). Is this what you're planning on using? If so, your circuit will not work. Read my answer for an explanation as to why. \$\endgroup\$ Sep 25, 2017 at 6:41

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