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Bone conduction low frequency speaker

Alain Hubrecht

Dec 9, 2017
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Dec 9, 2017
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I want to output very low frequency onto the skull bone. I think about buzzer or piezzo. It is just to output always the same frequency. I look for about 10 Hz, that is not possible for a speaker, so I will use something higher, pulsating at 10 Hz.
I guess a small circuit can produce the waveform, but what to use for the speaker? It should be the smallest possible.
Tx
 

Externet

Aug 24, 2009
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Welcome.
Not simple, but... Try an assortment of miniature relays with the coil in series with their C and NC contacts. Perhaps one will be close to 10Hz, or tailoring a resistor in series, or RC components to bring it to desired frequency.
It will mechanically buzz nicely.
 

Audioguru

Sep 24, 2016
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A piezo is a squeaker and cannot produce low frequencies with any force.
A small speaker has a high resonant frequency and also cannot produce low frequencies.
I agree that a relay might work.
 

AnalogKid

Jun 10, 2015
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A cell phone vibrator is a small DC motor with an offset weight. Maybe you can vary the DC voltage to get the frequency you want.

ak
 

Audioguru

Sep 24, 2016
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Can you add weight to the speaker to reduce its resonant frequency?
Sure, but its loudness will be reduced a lot (because then it must work harder) and to make it loud enough it might burn out.
 

Audioguru

Sep 24, 2016
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A cell phone vibrator is a small DC motor with an offset weight. Maybe you can vary the DC voltage to get the frequency you want.
A properly damped speaker starts and stops immediately. A vibrator motor starts and stops slowly due to its inertia.
 
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