Data Sheet

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347. Shorter Siren Fade Out
Build the circuit shown and turn on the switch (62). Press the press
switch (61) for a while and you will hear the siren in soft volume. This
is because the 100W resistor (41) limits the current through the
speaker (93). Release the press switch (61) and wait for a while. You
will eventually hear the siren start breaking up and fading out. Since
there is a 5.1kW resistor (43) in this RC circuit, the siren should fade
out slightly sooner than in project #332 where a 10kW resistor (44) is
used because the RC time constant in this circuit is half the RC time
constant of that in project #332.
348. Lithium Batteries
Connect points C and D with the 1kW resistor (42) in project #347.
Press the press switch (61) for a while and you will hear gun shots in
soft volume. This is because the 100W resistor (41) limits the current
through the speaker (93). Release the press switch (61) and wait for
a while. You will eventually hear the gun shots start breaking up and
fading out.
While Alkaline batteries use manganese oxide to generate power,
lithium batteries use lithium metal or compounds as their anode, which
enable lithium batteries to last longer.
349. Pulse Code Modulation
Connect points A and B with the 4-wire (4) in project #347. Press
the press switch (61) for a while and you will hear the re siren in
soft volume. This is because the 100W resistor (41) limits the current
through the speaker (93). Release the press switch (61) and wait for
a while. You will eventually hear the re siren start breaking up and
fading out.
As discussed in project #229, your 3-in-1 (11) stores samples of the
analog sounds that it produces. These samples are converted to a
digital bit stream typically through pulse code modulation (PCM). PCM
takes samples of the original analog signal amplitude, quantizes them
and then converts the quantized amplitudes to a digital bit stream.
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