8 Note Tune Player

This neat little circuit can play 8 note tunes at any speed you want. You select the notes with 8 trim pots. The speed in selected through a ninth pot. The circuit draws very little power and can be powered by a 9 volt battery, with the addition of a 7805 regulator to power the TTL logic used.

Schematic

Parts

Part Total Qty. Description Substitutions R1 1 10K Trim Pot   R2 1 1K 1/4 W Resistor   R3, R4, R5, R6, R7, R8, R9, R10 8 500 Ohm Trim Pot   C1, C3 2 10uF 12V Electrolytic Capacitor   C2 1 1uF 12V Electrolytic Capacitor   U1 1 555 Timer   U2 1 7490 Binary Counter 74LS90, 74HC90 U3 1 7445 BCD To Decimal Decoder 74LS45, 74HC45 U4, U6 2 7404 Hex Inverter 74LS04, 74HC04 U5, U7 2 4016 Quad Bilateral Switch   U8 1 3909 LED Flasher/Oscillator   SPKR1 1 8 Ohm 500mW Speaker   MISC 1 Board, Wire, IC Sockets

Notes

1. R1 controls the speed at which the notes are played. R3-R10 control the pitch of those notes.
2. The circuit will operate fine on a 9V battery, with the addition of a 7805 regulator to power the TTL logic used.
3. The missing pin on U2 is pin 14.