utilizing ldr for alarm lamp
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simple automatic street light system
The left-hand side transistor T1 is configured as a voltage comparator utilizing a resistive network. The resistor in the upper arm is a light-dependent resistor (LDR), while the lower arm resistor is a preset resistor used to establish threshold values....
Light/Dark Detector relay
This handy little circuit can tell the difference between darkness and light, making it very useful for switching on and off signs, porch lights or other things when it gets dark or light. More: R1 Adjusts sensitivity
The circuit described is...
No Doze Alarm Circuit
This circuit emits a loud tone if the input switch (S2) is not retriggered at designated intervals. If the user falls asleep and fails to re-trigger the circuit, it will continue to sound until S2 is pressed.
The circuit operates on...
Visible and Infrared Light Detectors
The sensors used are silicon phototransistors and Cadmium Sulfide (CdS) photocells. Both of these sensors allow less current to flow when they are dark than when lighted. Phototransistors change their conductance while photocells change their resistance depending on the intensity...
Alarm Power Supply
This power supply is suitable for a modular burglar alarm but can also serve other applications. It is designed to provide a 12-volt output with a current capacity of up to 1 amp. In case of mains failure, the backup...
Light to Frequency Converter TSL220
A large area photodiode and current-to-frequency converter integrated into a clear plastic 8-pin DIL package. The output generates a pulse train whose frequency is directly proportional to the light intensity. It is CMOS compatible (a 3.3kΩ pulldown resistor is recommended...
automatic pet feeder
An automatic feeder dispenses food based on the activation of a series of buttons, which interface with a system controller and a food dispenser. The system is designed for intelligent processing of inputs and outputs, allowing dynamic configuration of button...
Light Sensor Circuits
Dark Activated Switch or Porch Light Switch. This circuit activates a relay when the light level drops below a preset threshold. The light sensitivity can be adjusted using variable resistor VR1, and the relay contacts can control an external light...
Security Monitor
This circuit can be utilized in a garden setting to detect unusual sounds or wildlife noises. It can also monitor sounds around a car parked in a remote location. The cable used for the setup can either be visible or...