CIRCUIT IDEAS
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 cross-
ing, the triac (BT136) triggers to drive a
200W bulb.
The 6.8V power supply is taken di-
rectly 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
Pin Assignments of IC TT6061A
Pin No.
1
2
3
4
5
6
7
8
Pin name
CK
FI
V
DD
TI
CI
NC
V
SS
AT
Function description
System clock input
50Hz line frequency
Power input pin for V
DD
Touch input
Sensor control input
Not connected
Power input pin for V
SS
Angle-trigger output
TOUCH DIMMER
K. KRISHNA MURTY
I
VED
DWI
S.C.
B
y simply touching this touch dim-
mer you can increase the light in-
tensity of incandescent lamps in
three steps. The touch dimmer is built
around 8-pin CMOS IC TT8486A/TT6061A
specifically manufactured for touch dim-
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 exter-
nal components. For touch plate, you can
use a simple copper plate of 1cm脳1cm or
mer applications.
Initially, when mains switch is 鈥榦n,鈥?/div>
the bulb is 鈥榦ff鈥? Now, if you touch the
touch plate, the bulb glows dimly. On
even the end of the lead wire. Touch plate
is coupled to the touch detector through
820pF, 2kV capacitors C1, C2, and C3 con-
nected in series. Internally IC TT6061A鈥檚
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 鈥榦n.鈥?/div>
Note.
The IC had been procured by
the author from SM Semiconductors,
Santacruz (W), Mumbai.
DECEMBER 2003
ELECTRONICS FOR YOU
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