Operational Amplifier Tutorial & super microphone circuit

Afroman goes over the basics of how to use an operational amplifier to amplify tiny voltages, and builds a circuit to listen to very faint sounds with a microphone. Don't forget to vote 5!

The final microphone amplifier circuit diagram is here:
http://www.afrotechmods.com/groovy/amplifier_tutorial/amplifier_tutorial.htm

For more information about amplifiers, Google "inverting amplifier" "non-inverting amplifier" "instrumentation amplifier" "class A amplifier" "class B amplifier" "class AB amplifier" and that should give you a lot to chew on.

Category:

Science & Technology

Tags:

• amplifier
• circuit
• electronics
• op
• amp
• operational
• spy
• ear
• listening
• electrical
• engineering

[DarthInsidiom]

Awesome video. I'm trying to increase the sensitivity of a piezo transducer to use as a vibration sensor. Could I use the above circuit to increase the sensitivity or gain of said transducer to drive an LM3915N display driver??? Basically I'm using the transducer as a vibration sesnor and I want it to be really sensitive so I just about have to just think about vibration and the LED driver will display on the LED's. ;)

[Afrotechmods]

Piezos put out really high voltages with just the slightest amount of pressure. It might not be sensitivity that is your problem, maybe you just need a buffer. In any case yeah try the circuit it might do the trick. Also you can look up analog accelerometers +/- 1.5g or +/-2g.

[Ray55467]

will this work for 8 ohms 0.3 watt speaker ??

[Afrotechmods]

This circuit isn't suitable for low impedance speakers like that.

[haz939]

Could a use a NE5532 op-amp instead?

[Afrotechmods]

Why not? NE5532s are great.

[kinsi55]

here´s some more cat noises :D

[exxodas]

Sir, not to sound gay but... I fucking love you!!!!

[monkeyssj5]

thank you i loved the circuit but i want to know about -9v and could i use the circuit diagram for 3v/6v is their need for changing the resistance

[PhuckHue2]

Are two 220uF caps really needed if I use 2 batteries? Wouldn't 1 cap be enough? opamps draw very little current

[ebird97]

filtering 

[kennyfication88]

Thanks mate!

[100Xprafa]

Ajudou muito thank you !!!^^

[NTG56]

Dunno if he's gonna respond, haven't seen him on here in a while, so I'll take a shot at this:

You could use a charge pump circuit with a 555, but that's not the best way to do things. Look up Afromans tutorials on adjustable voltage regulators and the one on transformers. Get a centertap 12V transformer and use an LM337T & LM317T to regulate the negative & positive voltages. You'll be able to adjust over a wide range and get well regulated +/- V from one power supply that way.

[kennyfication88]

You need two to create a negative 9V output.