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I want a circuit diagram to make a simple audio amplifier circuit from which I can hear my voice louder. Thanx in advanc Answered

.How can I make it? I want a circuit diagram that's easy to construct with less components.I'm a ninth grader and want answers likewise. Many many thanks in advance!


There are way too many to suggest. Might I recommend going to a search engine (for this one, try Yahoo!)  and plug in:

microphone amplifier schematic

After you press Enter, choose from, usually, Web or Images. There are literally thousands to choose from. One thing you must know before deciding on which one to use is what type of microphone you will be using, Dynamic or Electret. Examples are: dynamic - Shure SM-58, electret - Lavalier (the kind you see worn on the shirt on TV). They are different beasts and need slightly different circuits. The Dynamic Mic does NOT need a voltage supplied to the mic itself while the Electret Mic DOES need a voltage supplied to the mic itself to work.

Take a look at the links I have provided and you should be able to find a suitable build. Good luck, be safe and have fun.


I would like you to understand that the SpyGear most likely uses at least 1 IC and mostly SM (Surface Mount) parts to get its compact size. If you are not experienced with SM parts, you'll have a real hard time duplicating the size of it. Besides, SM parts really only work well on a real, designed, PCB board.

That said, you, as a freshman in high school, know the value of research. Go back to your search engine of choice and try this term (without quotes):
"electret microphone voice amplifier schematic, 1.5 volt to 3 volt"
"low voltage electret microphone voice amplifier schematic"
You might also want to add "discreet components" to help narrow it down.

Electret (condensor) microphones will be your choice because of their size, unless you can find a dynamic mic of extremely small size, which is highly doubtful. If you cannot source a mic that works at those voltages, you'll have to compromise and use more button batteries (for compactness) to meet the required level.

I will give you a bit of a hint: use Yahoo! search and put the first search term above into it. One of the first links should be to DiscoverCircuits.com and the first link there should be to RedCircuits.com. This will probably be what you are looking for.

Have fun exploring, and let us know what you've decided to do.


If suppose there is a 47 ohm SM resistor in the actual Spy GEAR Micro Agent Listener circuit then why can't I use a 47 ohm "non-SM" resistor in place of it because the values are all remaining the same! and MANy,MANy,manY thanx!!!!

"anubhavtalukdar007 (author) says:
If suppose there is a 47 ohm SM resistor in the actual Spy GEAR Micro Agent Listener circuit then why can't I use a 47 ohm "non-SM" resistor in place of it because the values are all remaining the same! and MANy,MANy,manY thanx!!!!"

There is no reason not to. If it fits, go ahead. Just try to make the lead length as short as possible to cut down on stray capacitance, which could cause squeals or other such sounds, electronically.

Good luck and welcome to the gratifying world of electronics construction!


The internet is awash with simple amplifier circuits - I can do no better than point you at the following;




thanx for ur quick reply rick but the searches either point out to very complex circuits or the simple ones that don't show where to place the mic!!!

The mic is connected to the input.

generally this will be on the left side of the circuit with the output being on the right. As in the attached LM386 Amp cctc don't get much simpler.

Or you could buy a powered speaker fro a PC or walkman. These already have a battery powered amp in them.


Funny the diagram looks Ok on my screen buy doesn't copy well. You can however see what I mean.

thanx @rickharris u have worked enough on this! But I want a schematic for a Spy Ear like toy a good example is the SPY Gear Micro Agent Listener! If any1 can give me the schematic I dont know how will i ever thank them!!!!!!!!!!!