09-04-2012, 12:45 PM
VARIABLE TIMER WITH MUSIC
[attachment=19750]
This simple timer can be set to
run for different time settings
(30 seconds to 4.5 minutes).
Also, a musical note is played at the
end of the set timing.
Timer IC
NE555 ( IC1)
is wired as an
astable multivibrator
(AVM).
The AVM is set
to 0.033Hz frequency
using
preset VR1. It
means that the time period is around
30 seconds. The output of IC1 goes
high for around 20 seconds and low for
around 10 seconds. As it changes from
low to high, decade counter IC CD4017
(IC2) is advanced by one count. IC2
has ten outputs Q0 through Q9.
When rotary switch S3 is connected
to Q1 output of IC2 and reset
switch S2 is pressed, a musical note
is heard after a few seconds for 30
seconds. For positions 2 to 9, the silent
period increases by 30 seconds at each
step. At position 10 of rotary switch
S3, the delay will be of four and a half
minutes, followed by 30 seconds of
music.
The best way to think about this
is that positions 1 to 9 add 30-second
delay each. If you let the timer continue
to run, it repeats the tune every
5 minutes, irrespective of the setting
of S3.
Check that IC2 outputs run
through the correct sequence (each
high for 30 seconds). Wire the loudspeaker
to its terminal pins using
external wires. Fix rotary switch S3 in
the front panel for selecting the time.
The positions of rotary switch S3 can
be labeled with stick-on tape labels.
A simpler technique is to punch small
discs from insulating tapes of various
colours and stick these around the
knob
[attachment=19750]
This simple timer can be set to
run for different time settings
(30 seconds to 4.5 minutes).
Also, a musical note is played at the
end of the set timing.
Timer IC
NE555 ( IC1)
is wired as an
astable multivibrator
(AVM).
The AVM is set
to 0.033Hz frequency
using
preset VR1. It
means that the time period is around
30 seconds. The output of IC1 goes
high for around 20 seconds and low for
around 10 seconds. As it changes from
low to high, decade counter IC CD4017
(IC2) is advanced by one count. IC2
has ten outputs Q0 through Q9.
When rotary switch S3 is connected
to Q1 output of IC2 and reset
switch S2 is pressed, a musical note
is heard after a few seconds for 30
seconds. For positions 2 to 9, the silent
period increases by 30 seconds at each
step. At position 10 of rotary switch
S3, the delay will be of four and a half
minutes, followed by 30 seconds of
music.
The best way to think about this
is that positions 1 to 9 add 30-second
delay each. If you let the timer continue
to run, it repeats the tune every
5 minutes, irrespective of the setting
of S3.
Check that IC2 outputs run
through the correct sequence (each
high for 30 seconds). Wire the loudspeaker
to its terminal pins using
external wires. Fix rotary switch S3 in
the front panel for selecting the time.
The positions of rotary switch S3 can
be labeled with stick-on tape labels.
A simpler technique is to punch small
discs from insulating tapes of various
colours and stick these around the
knob
what is uses? and what is applications?