[SOLVED] audio amplifiers to amplify voice signals

[asifanwarbaig]

I need to have a high gain amplifier i have been using LM324 but couldn't get satisfactory results from a distance of atleast 50 cm, i need an amplifier that gives me high gain to read signals upto 1m clearly atleast using it for a propeller detector of a RC brushless motor.

 

[zoulzubazz]

you could switch to a two stage architechture. the first being a pre-amp active filter stage (possibly a bandpass filter for audio signals) and a second stage which brings the signal to your required gain. HTH.

 

[arouse1973]

Hello
Can you tell us a bit more on what your trying to do? What signals are you reading in? Are you using a microphone or something else? To be sensitive enough to pick up audio 1 m away this would need a large gain amplifier unless the external noise source was very loud. This means it may pickup other sources of noise in the environment, is this going to be an issue? Can you post a circuit diagram and maybe some pictures of what you have done already?

Thanks
Adam

 

[jiripolivka]

For picking up audio signals over a distance >50 cm, you need first a directional microphone. Best use a standard low-cost electret microphone and put it on one end of a long paper or plastic pipe to get directionality.
Use e.g. LM386 audio amplifier set to high gain. If you want to use the LM 324, set one or two stages with a lower gain (x10), then cascade thye stages for a good result.

 

[asifanwarbaig]

hie there,

what i am trying to do is to pick up a full throttle RC motor sound from distance then i need to amplify those signal to acquire it's position , this is done using mic's but i am not able to amplify the signal properly

 

[asifanwarbaig]

yes i have been using filters to reduce noise but it's not helping much with that amplifier ,, though it is picking up vibrations clearly but i don't need that and require to capture noise from air

 

[arouse1973]

Please supply, as already asked, circuit diagram and pictures.
Thanks
Adam

 

[Audioguru]

An LM324 is a noisy antique opamp. You should use an opamp designed and used for audio equipment like an TL071 single, TL072 dual or TL074 quad audio opamp, but there are many others.
Don't put the mic in a tube that was suggested because then the tube will cause a huge resonant peak. Directional electret mics have a vent on their rear and sides to make them directional.

I use my ears to hear the propeller sound from my RC airplanes and use my brain to compare its frequency with a tone from Audacity program on my pc.
A problem is that the number of blades sets the octave of the sound, a two blade prop makes a sound one octave higher than the RPM and a 3 blade prop makes the sound 3 octaves higher.
Sometimes the fuselage or wings resonate at the true RPM frequency if the prop is a little unbalanced then the sound is the true RPM.

 

[asifanwarbaig]

thanks a lot for your support guys i have been using LM358 Op-Amp for high sound gain and got the expected results. sound detection is upto 4m.