This low-cost, general-purpose electronic hearing aids works off 3V DC (2×1.5V battery). Transistor T1 and associated components form the audio signal preamplifier for the acoustic signals picked up by the condenser microphone and converted into corresponding electrical signals.
The medium-power amplifier section is wired around popular audio amplifier IC TDA2822M (not TDA2822). This IC, specially designed for portable low-power applications, is readily available in 8-pin mini DIP package. Here the IC is wired in bridge configuration to drive the 32-ohm general-purpose monophonic earphone.
The audio output of this hearing aid circuit is 10 to 15 mW and the quiescent current drain is below 1 mA. The circuit can be easily assembled on a veroboard. For easy assembling and maintenance, use an 8-pin DIP IC socket for TDA2822M.
Hearing aids circuit wiring diagram
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Mahaya
Interesting project..
Seems futurustic and portable
It’s an analog device not digital and takes 6mA minimum!!! Not a lot of use.
where’s the digital?
sucks
can anybody tell me what is the idea of that dotted line from on/off switch to VR1 varialble resistor??
friend:oftenly u would have been using a old radio model,when u do its volume lower and more lower after this there is a stage when volume sounds click and device gets off same this function is applied here
The dotted line indicates that the on off switch is part of VR1 variable resistor which is also the volume control.
the on/off switch is joined to the vr1 to indicate that it is a switch pot. The volume control and and on/off switch are the same device
This circuit gives excellent sound clarity.It is truly compact and portable.Omitting the LED indicator will decrease the current consumption.The design is analog.However it can cope with digital aids when it comes to sound reception and reproduction.
How we can modify the circuit to make it work like digital. If anyone tested the sound and working of this project, any feedback or humming noise out of it?
Please comment
Thanks
Hey Is there any way in which we can use a two ear headphones rather than a monophonic earphones
power slim for mp3
Isthere any hearing aid to listen speech,words spoken in rooms or gathering muffling various frequncy noise?
how to connect earphones …………cuz my earphones are not working
can we use two ear head phones instead of mono ear head phones in the same circuit
What are the major advancements on this hearing aid circuit
whether this circuit is functioning or not
Capacitors C1 and C2 seem to be large enough for a good low frequency response. However, I would connect VR1 to IC1 pin 7, to C2, and the VR1 runner to IC1 pin 7 (Just swap them). The reason for this, is when the runner of VR1 is turned down to minimum volume (nearest to the GND), the resistance that C2 will see, will be very low, and thus low frequencies will suffer. Our ears are less sensitive to low frequencies, and yet by turning the volume down, these frequencies are the first to diminish in the unmodified version of this design. C2 is large enough, when seeing a constant 10K of VR1, but NOT when it goes down when approaching GND. Oh, and get rid of LED1, it sucks! …. current! The TDA2822M is available as the DIL8 version, but also the SMD version of the same chip. WHY SHOULD THIS DESIGN BE DIGITAL, WHEN AN ANALOG DESIGN WORKS JUST FINE? On the whole, a very nice sweet and cheap design.
Dr. Spunk,
I have few questions about how to reduce the size of this circuit.
Thanks!
hi al.i did this circuit.and theres no problems in soldering and circuit connections.after completion i could hear sound in my headset only wen i switch the pot on nd off.its jst coz of the mic present in the headset…i did change a new condenser mic bt it doesn’t work at all.plz tell me wat to do now..can i replace condenser mic with something else????
Where can one buy this ic in the US?
Pls if I add a sound detection circuit b/w the preamp stage n the IC input such that the amplifier will be ON only when an accoustic pressure is detected, will it work? Coz i want 2 use it for a project. For the detection circuit I want 2 use LM324 Op-amp and NE555, so i need your assistance : even a followup comment, thanks.
hey! pls reply..
i m working on this project and i m not getting the output… the capacitor before the mic shows 0.7V but deres no dc voltage on mic…pls temme the reason.
also i cant get how to connect the potentiometer…
plz help…its urgent…
Are you sure you are using an electret capacitor microphone? like this one:
digikey.com/product-detail/en/CMA-4544PF-W/102-1721-ND/1869981
Link to specs are on this page.
A dynamic mic will measure low DC voltage and have much lower output signal –especially if “paralyzed” by DC bias current.
On the potentiometer, the center pin is the arm –if you get the other two swapped, it simply reversed the direction of rotation.
I want a better explanation.