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
R1___________10K Trim Pot
R2___________1K 1/4 W Resistor
R3,R4,R5,R6__500 Ohm Trim Pot
R7,R8,R9,R10_500 Ohm Trim Pot
C1,C3________10uF 12V Electrolytic Capacitor
C2___________1uF 12V Electrolytic Capacitor
U1___________555 Timer
U2___________7490 Binary Counter
U3___________7445 BCD To Decimal Decoder
U4,U6________7404 Hex Inverter
U5,U7________4016 Quad Bilateral Switch
U8___________3909 LED Flasher/Oscillator
SPKR1________8 Ohm 500mW Speaker
MISC_________Board, Wire, IC Sockets
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.