As tiny sound generator we use an Integrated Circuit (IC) called “Hex Schmitt Trigger Type 74HC14” which was never intended for making sound. It consists of six identical inverters and with two of them we will build one simple oscillator by using 1 resistor, 1 capacitor, 1 diode (optional), 1 solar cell and 1 piezo speaker.
It is a very cheap, loud and simple project that can be made in about 30 minutes.
Step 1: Tools and Parts
A 1 x CMOS IC SN 74 HC 14 N DIP
B 1 x Capacitor 10 uF
C 1 x Resistor 1k or 10k Ohm
D 1 x Diode BAT 43 (optional)
E 1 x Solar Cell 4,5 V / 35mA (or use an old garden light panel)
F 1x Piezo Speaker (PIEZO-SUMMER KPI-G2313L-6260) or similar
G 1 x Wires
H 2 x old mini Speaker Cases, for Piezo Speaker and Circuit
Step 2: Integrated Circuit (IC)
Start with soldering it to Pin 1 and Pin 4 of the IC.
Make sure that the mark of the IC is on the left side!
Step 4: Resistor and Diode
Next on our soldering list are the resistors and the diode.
Solder the resistor to Pin 3 and Pin 4 of the IC.
Even if it is not necessary you can also solder the diode (in parallel to the resistor) to Pin 3 and Pin 4 of the IC.
This will make a nice saw tooth wave sound.