To propose a circuit using 555 timer that will give us to see our thing in the cabinet.
The 555 timer IC is component like chip that used to variety timer, pulse generation, and oscillator applications. The 555 used for delays time,in a oscillator and in flip-flop. It derivative become one package. In the package consist of two 556 or 558 timing cicuit.
Internal Block Diagram
• Green: within the positive power supply and the ground ,there are connection of 3 resistor,the resistor must be same.Control voltage pin are connected to the latter.
• Yellow: Negative input of the comparator are connected to the 2/3 Vcc,while the positive are connected to the Threshold pin
• Red: positive input of the comparator are connected to 1/3 Vcc while the negative input are connected to the trigger pin.
• Purple: the state of timer is stores by the SR flip flop that are controlled by two comparator, so that the the timer can be rest at any time..
• Pink: the output pin can load until 200mA due to the output of flip flop followed with the output stages of the push-pull.
• Cyan: the flip flop output on the transistor and the connect to the discharge pin of the component.
1 GND Power Ground supply: the connection must be to the ground,zero voltage.
2 TRIG Input Trigger: negative input of 1/3 Vcc are connected to the trigger pin.
3 OUT Output Output: : the output pin can load until 200mA,output of flip flop followed with the output stages of the push-pull.
4 RESET Input Reset: timer that are stores in SR flip flop that are controlled by two comparator, so that the the timer can be rest at any time..
5 CONT Input Control (or Control Voltage): this pin provides access to the internal voltage divider (2?3 VCC by default).
6 THRES Input Threshold: the positive of 2/3 Vcc are connected to the Threshold pin
7 DICSH Output Discharge: . the flip flop output on the transistor connect
8 Vcc Power Supply the electrical current
Charging and Discharging process
The control voltage(Vcont) changes the threshold value of the 1/3 Vcc and 2/3 Vcc for the internal comparators. With the control voltage, the upper value is Vcont and the lower value ½ Vcont. When the control voltage is varied, the output frequency also varies. An increasing in Vcont increases the charging and discharging time of the external capacitor and causes the frequency to decreases. A decreases in Vcont decreases the charging and discharging time of the capacitor and causes the frequency to increases.
Duty cycle =(tH/T)100%=(tH/tH+tL)100%
Duty cycle=(R1+ R2/R1+2R2)100%
Operation of 555 timer
Features of 555 timer IC
• It operating within +5 V until +18 V of voltage supply
• The current is loaded in sinking and sourcing is 200mA
• Choose the correct external component of the circuit because it timing interval will be done in several minutes so that the frequency will be exceed hundred kilo Hz
• The high current of the output causes the output of the 555 timer derive a transistor- transistor logic.
• It has a temperature equivalently 0.005 %/ °C.
• The timer of the duty cycle can be adjust at any time.
• 600nW per package is the maximum power dissipation.