10-08-2012, 01:15 PM
TOUCH DIMMER
[attachment=30940]
By simply touching this touch dimmer
you can increase the light intensity
of incandescent lamps in
three steps. The touch dimmer is built
around 8-pin CMOS IC TT8486A/TT6061A
specifically manufactured for touch dimmer
applications.
Initially, when mains switch is ‘on,’
the bulb is ‘off’. Now, if you touch the
touch plate, the bulb glows dimly. On
second touch, the bulb gives medium light.
At the third touch, the bulb is driven
fully. Another touch puts off the light.
Since the IC is highly sensitive, use a
long wire to connect the IC to the touch
sensor. The circuit uses minimum external
components. For touch plate, you can
use a simple copper plate of 1cm×1cm or
even the end of the lead wire. Touch plate
is coupled to the touch detector through
820pF, 2kV capacitors C1, C2, and C3 connected
in series. Internally IC TT6061A’s
touch signal is connected to the counter/
decoder via a resistor and clock input CK
is connected to the counter/decoder via a
frequency generator.
Line frequency signal is taken through
R4 at pin 2 of IC TT6061A. At zero crossing,
the triac (BT136) triggers to drive a
200W bulb.
The 6.8V power supply is taken directly
from mains through resistors R1 and
R3, diode D3, capacitor C4, and zener
diode and fed to power-input pin 3 of the
IC. Capacitors C1, C2, and C3 connected
between touch input pin 4 and touch plate
remove the shock potential from the touch
plate, so do not replace these capacitors
with a single capacitor or with a capacitor
of a lower voltage rating. Mains potential
exists in the circuit. Needless to say, it is
dangerous to touch the circuit when mains
is ‘on.’
[attachment=30940]
By simply touching this touch dimmer
you can increase the light intensity
of incandescent lamps in
three steps. The touch dimmer is built
around 8-pin CMOS IC TT8486A/TT6061A
specifically manufactured for touch dimmer
applications.
Initially, when mains switch is ‘on,’
the bulb is ‘off’. Now, if you touch the
touch plate, the bulb glows dimly. On
second touch, the bulb gives medium light.
At the third touch, the bulb is driven
fully. Another touch puts off the light.
Since the IC is highly sensitive, use a
long wire to connect the IC to the touch
sensor. The circuit uses minimum external
components. For touch plate, you can
use a simple copper plate of 1cm×1cm or
even the end of the lead wire. Touch plate
is coupled to the touch detector through
820pF, 2kV capacitors C1, C2, and C3 connected
in series. Internally IC TT6061A’s
touch signal is connected to the counter/
decoder via a resistor and clock input CK
is connected to the counter/decoder via a
frequency generator.
Line frequency signal is taken through
R4 at pin 2 of IC TT6061A. At zero crossing,
the triac (BT136) triggers to drive a
200W bulb.
The 6.8V power supply is taken directly
from mains through resistors R1 and
R3, diode D3, capacitor C4, and zener
diode and fed to power-input pin 3 of the
IC. Capacitors C1, C2, and C3 connected
between touch input pin 4 and touch plate
remove the shock potential from the touch
plate, so do not replace these capacitors
with a single capacitor or with a capacitor
of a lower voltage rating. Mains potential
exists in the circuit. Needless to say, it is
dangerous to touch the circuit when mains
is ‘on.’