Sonic Output Indicator
Tom Grey's "sonic LED"
In a 2003 Yahoo BEAM list post,
Tom Grey presented his sonic output indicator (intended as a
replacement for an LED as a process state indicator):
I have been having fun linking a hexcore to
Wilf's BEAM sound effects circuit--the two influence each
other and make a most interesting mix of sounds. That got
me interested in having sounds as output indicators,
where we customarily use LEDs.
I'm not entirely happy with it, as it runs at 80 mA
even when it's quiet (the 6-Nv ladder [some people
call this a 'spinal cord'?] uses 34 mA by itself) and
it makes some pretty raspy square-wave type beeps, but it
DOES work. I am always happy when I design even
more-or-less works! 8^D Don't ask me *how* it works, I'm
not there yet. I did discover that the diodes (1N418
type) are needed to keep the sound oscillator from
resetting the process in the spinal cord. I also found
that I couldn't use the last Nv in the ladder to hook to
a sound or it sent the ladder into a frenzy, don't know
You can tell where I'm headed--a noisy bot that chirps
and chortles and whistles and snorts as it goes about its
life. What I need is something of the cheerful whistles
and warbles of Wilf's sound effects that will turn on in
response to a Nv output, and remain quiet otherwise,
without eating current. (I don't ask for much!)
In a subsequent
post, Wilf Rigter simplified the circuit slightly:
Well here is a quicky mod of your original
circuit that should have much lower current.
The audio oscillator modification fixes the high
frequencies that were the main problem. The resistor cap
values may be changed to suit. I suggest much larger
resistors and smaller caps to reduce power.
The pushbutton input now gives one clean pulse to
start the sequencer. A logic start signal can be coupled
via the diode.
The 3 diode OR gate is changed to give a good logic
signal for the tristate pin.
It should be much better behaved so that there is no
disturbance of the sequencer operation allowing for more
As you have probably found ourt by now, there are
plenty of designs that make noise but only a few are
pleasing to the ear and even fewer are worth listening to
for any length of time. Those are the keepers.
I have no idea what your circuit sounds like so a
small (?) audio file to the file section might be