Organize and Share your Electronics the way you want. Sign-Up for a free account now. It takes only 30 seconds!

AT89C2051 Night light saver

AT89C2051 Night light saver

The Saver V5.0 runs simple clock emulation program, turns a night light on and off with preset time, say 1900hrs to 2200hrs everyday. The design features low cost, easy installation, no battery backup and no EMI. The AT89C2051 uses external oscillator generated by schmitt trigger gate CD4093, 680kHz. Reference frequency was derived from 50Hz main line.
Explanation of the circuit operation for each parts is as follows;
1)Transformerless direct supply: R1 and C1 forms a simple current limitting AC source. D1 and D2 converts AC to DC with C2 performing a reservoir. D3 limits voltage across the circuit to ~5V.

2)External oscillator: A reliable schmitt gate oscillator with R8 and C5 produces clock approx. 680kHZ. One machine cycle is ~18us.

3)89C2051 circuits: C4, 33uF and R4, 10k forms a reset circuit that need time for riasing logic at least two machines cycle. S1 is a momentary button for setting time to 18:00 by pulling P3.0 to logic low. The functioning LED is connected to P3.7. Q2 is a small triac MAC97A6, and is drived by Q1, PNP transistor sinking through P1.7.

4)Reference frequency: R3 and C3 integrates a 50Hz main frequency and unwanted transients producing triangle-like waveform which is fed to U2 schmitt gate. The output pin4 is clean 50Hz square wave tied to int0.

Visit Here for more.







 

More Articles to Read

Peeqo is a desktop bot that communicates through GIFs
Peeqo is a desktop bot that communicates through GIFs
Using a Programmable Input Multiplier to Minimize Integer Boundary Spurs
Using a Programmable Input Multiplier to Minimize Integer Boundary Spurs
Serial seven segment LED display shield
Serial seven segment LED display shield
G-code controlled drawing plotter
G-code controlled drawing plotter
An Arduino round word clock
An Arduino round word clock
The Sandwich-o-Matic will make your lunch automatically
The Sandwich-o-Matic will make your lunch automatically
Scalar Network Analyser Jr
Scalar Network Analyser Jr
An Arduino-controlled automated whiskey distillery
An Arduino-controlled automated whiskey distillery
The Rex800 looks like a dinosaur Terminator
The Rex800 looks like a dinosaur Terminator
Home Environment Monitor
Home Environment Monitor
Understanding the Operation of the Frequency Synthesizer in Maxim’s RF Transceivers
Understanding the Operation of the Frequency Synthesizer in Maxim’s RF Transceivers
App note: EPIC: Electro-Pyrotechnic Initiator Chip Resistor
App note: EPIC: Electro-Pyrotechnic Initiator Chip Resistor
Noisy ESP8266
Noisy ESP8266
App note: Noise analysis for high-speed op amps
App note: Noise analysis for high-speed op amps
Skill Sunday: Arrays
Skill Sunday: Arrays
App note: Infrared remote control implementation with MSP430FR4xx
App note: Infrared remote control implementation with MSP430FR4xx
Gesture Controlled Smart Home
Gesture Controlled Smart Home
Design for a Wideband, Differential Transimpedance DAC Output
Design for a Wideband, Differential Transimpedance DAC Output
Wrist thrusters let you fly through the water effortlessly
Wrist thrusters let you fly through the water effortlessly
Bertan/Spellman 225-20R HV power supply teardown
Bertan/Spellman 225-20R HV power supply teardown

Top


Shares