Using a CMOS IC TT8486A TT6061A you can build a very simple dimmer circuit which can be used to control intensity of an incandescent lamb by simply touch a contact . This electronic touch dimmer circuit can increase the light intensity of incandescent lamps in three steps.
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 and another touch puts off the light.
This sensitive touch light dimmer circuit uses minimum external components and can be used for 110V or 220V AC by simply changing some external components . For touch plate, you can use a simple copper plate of 1cm×1cm (a small piece of PCB) or even the end of the lead wire. Touch plate is coupled to the touch detector through 1000pF, 2kV capacitors C4, C5 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.
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This light dimmer circuit require a 6.8 volts power supply, which is taken directly from mains through resistors R2, diode D1, capacitor C2, and zener diode and fed to power-input pin 3 of the IC. Capacitors C4, C5 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.
Te circuit diagram shown here is just for 110 volts ac , if you want to use this touch sensitivity light dimmer for 220 volts AC , you need to chance some components value .
For 220 volts usage you’ll need to change R1 510K TO 620K ( FOR 60HZ CHANGE TO 50HZ ) , R2 20K/1W TO 40K/2W ( FOR 110V CHANGE TO 220V ) and R6 1M TO 1.5M ( FOR 110V CHANGE TO 220V ) and also you can add an additional capacitor in series with the C4 and C5 ( capacitor used must be the same type an value ) .
S: electroniq.net/other-projects/tt8486a-tt6061a-sensitive-touch-light-dimmer.html
