My Light Diagram

This is same circuit as above with the addition of a photo resistor to trigger the flip flop instead of a push button. The bias resistor in series with photo resistor was chosen so that sufficient voltage is present at the base of the 2N3904 to supply current to the circuit in ambient lighting conditions. The circuit should toggle when the photo resistor is hit by a flashlight beam or other fast changing light source. Slow changes in light intensity will have no effect unless the light gets too bright to maintain sufficient bias for the 2N3904. Light Activated Relay Circuit diagram :

Sound Activated Switch Circuit diagram : Control by sound may be very useful,  not just on a robot but also for a bit  of home automation, for example a  sound activated light responding to a  knock on the door or a hand clap. The  light will be automatically switched  off after a few seconds. An alternative  use is burglar protection — if someone  wants to open the door or break some-thing the light will come on, suggesting  that someone’s at home. The circuit can work from any 5– 12 VDC regulated power supply pro-vided a relay with the suitable coil voltage is used.   Sound Activated Switch Circuit diagram :   Sound Activated Switch Circuit Diagram When you first connect the supply  voltage to the circuit, the relay will  be energised because of the effect of capacitor C2. Allow a few seconds for  the relay to be switched off. You can  increase or decrease the ‘on’ period  by changing the value of C2. A h...

This circuit uses an MC2830 to form a voice activated switch ( VOX ). A traditional VOX circuit is unable to distinguish between voice and noise in the incoming signal. In a noisy environment, the switch is often triggered by noise, or the activation sensitivity must be turned down. Voice Activated Switch Circuit Diagram:   This circuit overcomes this weakness. The switch is activated by voice level above the noise and not activated by background noise. This is done by utilizing the differences in voice and noise waveforms. Voice waveforms generally have a wide range of variation in amplitude, whereas noise waveforms are more stable. The sensitivity of the voice activation depends on the value of R6. The voice activation sensitivity is reduced from 3.0dB to 8.0dB above the noise if R6 changes from 14k to 7.0k .

The following post illustrates a simple light toggled/operated remote control circuit, which can be activated by an ordinary flashlight or more effectively through a laser beam unit (key chain type). The circuit idea may be understood with the below mentioned points: Transistor T1 alnog with R3, C6 and the LDR itself forms a simple light sensor stage.  The LDR is connected across the base of the transistor and the positive supply such that when light falls over the LDR, T1 receives the required base bias and conducts.  When T1 conducts, the high potential at pin 14 of IC1 is pulled to logic low. However since a logic low wouldn't effect pin#14, IC1 does not respond as yet. The moment light on the LDR is switched OFF, T1 is switched OFF and pin#14 now instantly receives a subsequent logic high via R5.....now IC1 responds, and shifts it's output from pin#3 to pin#2. This makes pin#3 logic low, activating T2, and the preceding relay driver stage. The above condition pers...

With this sound activated switch, control by sound may be very useful, not just on a robot but also for a bit of home automation, for example a sound-activated light responding to a knock on the door or a hand clap. The light will be automatically switched off after a few seconds. An alternative use is burglar protection — if someone wants to open the door or break something the light will come on, suggesting that someone’s at home. The circuit can work from any 5–12 VDC regulated power supply provided a relay with the suitable coil voltage is used. Sound activated switch circuit diagram When you first connect the supply voltage to the sound activated switch circuit, the relay will be energised because of the effect of capacitor C2. Allow a few seconds for the relay to be switched off. You can increase or decrease the ‘on’ period by changing the value of C2. A higher value results in a longer ‘on’ period, and vice versa. Do not use a value greater than 47μF. Biasing resistor R1 det...