Rongge

The operation of the dimmer is based on phase control; during a full cycle of an AC waveform, a thyristor will only allow a part of the waveform to be delivered to the load. Take a look at the following waveforms:   The only difference is that the waveform on the left will bright the lamp higher than the waveform on the right. That is because, on the left waveform, the triac will be conductive earlier than the triac shown in the right waveform.  The time that the triac becomes conductive is symbolized with the Greek letter α (ALPHA) , called firing angle, so controlling this angle you can control the phase voltage, and is measured in angles from the zero point of the waveform. This zero point is the point that the voltage is 0 volts, and this happens 2 times every one full period of the wave form. When the α becomes smaller, then the dimmer becomes conductive sooner and the lamp is brighter. When the α becomes bigger, then the triac delays more to become conductive and thus th...

This is a simple PIC Security System Dials Your Cell Phone Circuit Diagram . Do-it-yourself phone dialer security system calls your cell phone, office etc. whenever a door or window is opened, or panic button is pressed. Great Home Alarm. PIC Security System Dials Your Cell Phone Circuit Diagram The circuit consists of a small PIC microcontroller, assembly program, and a few other parts to detect a switch closure from an open door, window, or manual push button and then dial the cell phone number, and transmit a steady tone to indicate the source of the call. The circuit uses the pulse dialing system to interrupt the line connection a number of times to indicate each digit. Pulse dialing (the oldest form of dialing) works by actually disconnecting or "hanging up" the phone line a number of times to indicate each digit. For example, the digit "5" would be dialed by disconnecting and reconnecting the line 5 times in short intervals of about 100mS. There is about a 1 s...

This is a Password based Door locking system with GSM. The project mainly consisting of PIC microcontroller (16F877), 16x2 LCD Display, GSM Modem, Keypad and misc.(Relay, Crystal oscillator, power supply which is not shown in circuit diagram) The program is compiled using PICC Compiler and simulated on Proteus 8. All Header and simulation files are given at the bottom of this post. The default password is set as 123. This project can be implemented anywhere where, higher security is required. If the user enters correct password, that is “123”, the relay gets active and opens the door. If an un-authorised person trying to access the system and enters the password incorrectly three times, the system gets locked and alert the owner by sms using Gsm modem. Once the system gets locked a count down timer will appear on lcd and you have to wait that predetermined time period. Read More.....