18-09-2012, 04:19 PM
CLAP REMOTE
[attachment=33988]
An infra-red or wireless remote control has the disadvantage that the small, handy,
remote (transmitter) is often misplaced. The sound operated switch has the advantage
that the transmitter is always with you. This project offers a way to control up to four
latching switches with two claps of your hand. These switches may be used to control
lights or fans—or anything else that does not produce too loud a sound.
To prevent an occasional loud sound from causing malfunction, the circuit is normally
quiescent. The first clap takes it out of standby state and starts a scan of eight
panel-mounted LEDs. Each of the four switches are accompanied with two LEDs—one for
indicating the ‘on’ and the other for indicating the ‘off’ state. A second clap, while the
appropriate LED is lit,activates that function. For example, if you clap while LED10 used
in conjunction with Lamp 1 is lit then the lamp turns on. (If it is already on, nothing
happens and it remains on.
A condenser microphone, as used in tape recorders, is used here to pick up the sound of
the claps. The signal is then amplified and shaped into a pulse by three inverters (N1
through N3) contained in CMOS hex inverter IC CD4069. A clock generator built from two
of the inverter gates (N5 and N6) supplies clock pulses to a decade counter CD4017
(IC2). Eight outputs of this IC drive LEDs (1 through 8). These outputs also go to the J
and K inputs of four flip-flops inside two CD4027 ICs (IC3 and IC4). The clock inputs of
these flip-flops are connected to the pulse shaped sound signal (available at the output
of gate N3).
Additional circuitry around the CD4017 counter ensures that it is in the reset state, after
reaching count 9, and that the reset is removed when a sound signal is received. Outputs
of the four flip-flops are buffered by transistors and fed via LEDs to the gates of four
triacs. These triacs switch the mains supply to four loads, usually lamps. If small lamps
are to be controlled, these may be directly driven by the transistors.
[attachment=33988]
An infra-red or wireless remote control has the disadvantage that the small, handy,
remote (transmitter) is often misplaced. The sound operated switch has the advantage
that the transmitter is always with you. This project offers a way to control up to four
latching switches with two claps of your hand. These switches may be used to control
lights or fans—or anything else that does not produce too loud a sound.
To prevent an occasional loud sound from causing malfunction, the circuit is normally
quiescent. The first clap takes it out of standby state and starts a scan of eight
panel-mounted LEDs. Each of the four switches are accompanied with two LEDs—one for
indicating the ‘on’ and the other for indicating the ‘off’ state. A second clap, while the
appropriate LED is lit,activates that function. For example, if you clap while LED10 used
in conjunction with Lamp 1 is lit then the lamp turns on. (If it is already on, nothing
happens and it remains on.
A condenser microphone, as used in tape recorders, is used here to pick up the sound of
the claps. The signal is then amplified and shaped into a pulse by three inverters (N1
through N3) contained in CMOS hex inverter IC CD4069. A clock generator built from two
of the inverter gates (N5 and N6) supplies clock pulses to a decade counter CD4017
(IC2). Eight outputs of this IC drive LEDs (1 through 8). These outputs also go to the J
and K inputs of four flip-flops inside two CD4027 ICs (IC3 and IC4). The clock inputs of
these flip-flops are connected to the pulse shaped sound signal (available at the output
of gate N3).
Additional circuitry around the CD4017 counter ensures that it is in the reset state, after
reaching count 9, and that the reset is removed when a sound signal is received. Outputs
of the four flip-flops are buffered by transistors and fed via LEDs to the gates of four
triacs. These triacs switch the mains supply to four loads, usually lamps. If small lamps
are to be controlled, these may be directly driven by the transistors.