Download filezillafor windows
The audio signal is tapped off via R3 (100KW), which is again required in rder
to eliminate any loading on the capacitor that would cause premature discharg-
ing of its stored voltage. The output level from R3 is not at TTL levels as it was
in the previous circuit, but instead it is very small at around 300mV (mil-
liVolts), so we need some amplification. This is in the shape of the good old
LM386 amplifier IC, which is capable of giving a good output volume yet still
work at 5 Volts. The circuit for the LM386 amplifier is shown below: - The full circuit is shown below laid out on the PROTON Development Board
MK2. Try increasing or reducing the value of C1 and listen to the chimes produced.
Also try changing the value of R2. 0V + - 6 4 5 3 2 LM386 VR1
100kW C8
100nF C9
100uF 10V Volume +5 Volts Input 100kW LM386 100uF 4.7uF 100nF - - + +
