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An electronic stethoscope is an easy and fun listening device to make. It only requires some basic knowledge of electronics, and can be built with so...
You will need: - 1-1/2" flat round cabinet knob - LM386 Low Voltage Audio Power Amplifier (Model: LM386 | Catalog #: 276-1731) - MPF102 Transistors (...
Using a sharp pair of scissors, trim your circuit board lengthwise so that only the center pads are left. Note: You may want to use a dust mask while...
Build the circuit tightly and as close to one side of the board as possible. For now, don't worry about including the power switch, audio jack, poten...
Once the bulk of your circuit has been built. Trim the board as small as possible in such a way that it won't interfere with the circuit itself, and r...
Flip your case on its side. Make two _ _ _ marks _ _ _ Drill these marks using a 1/4" drill bit.
On the two smallest sides of the case make centered marks. Drill an 3/16" hole on the side closest to the other holes that you have just made. Drill...
With the potentiometer knob facing towards you, solder a black wire to the left potentiometer pin. Solder red wire to the other two pins.
Solder a red wire to the center toggle switch pin. Solder the red wire from the 9V battery clip to either of the other pins.
Attach a single red wire to the two pins on the bottom of the audio jack. Attach a black wire to the ground pin on the side.
Install the potentiometer and toggle switch right next to each other inside the case. Install the audio jack into the 1/4" hole on the opposite end o...
Drill and 1/8" hole near the edge of the cabinet handle.
For our purposes, the flat side of the cabinet handle will be considered the front. Pass the red and black wires of the piezo through the hole you ju...
Take your audio cable and cut a 3 foot section of cable out of it. Don't worry about preserving the ends. We just need the shielded cable.
Peel back the cable and twist together the shielding to form one single wire and expose the signal wire to form another.
Solder the red wire from the piezo to the signal wire of the cable. Solder the black wire to the cable's shielding. Epoxy it all to the back of the ...
Pass the other end of the audio cable through the remaining hole in the case. Tie a single knot to prevent it from passing back through. Strip back ...
Complete the circuit as specified in the schematic. Note that the audio cable's shielding goes to ground and that the center pin from the toggle swit...
Plug in your 9V battery and install it inside the case. If all has been done right, it should fit snugly.
Put the lid on the case and screw it shut.
Attach your knob to the potentiometer.
Plug in your ear buds or headphones. I used a pair of headphones and ear protection to make passive noise canceling headphones (jackhammer headphones...
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