Creative Engineering Projects: ic555

OPTO-THERMO CONTROL RELAY SWITCH

By Creative Engineering Projects on 09:23 in 3rd semester, engineering project, ic555, LDR, optoelectronics, relay switch

1. ABSTRACT:

Ø The circuit shows the working of opto-control switch, where LDR is used as a switch to open and close the circuit.

Ø 555 timer IC is used as a comparator.

Ø The product of RC is used to produce the delay in the IC and affects pulse propagation through it.

2. COMPONENTS:

Ø Resistors (1k,47k,10k)

Ø Capacitors (2*.01uF, 1*4.7uF)

Ø IC LM555

Ø LDR (500 ohms)

Ø Speaker (8 ohms)

Ø Battery 9V

3. CIRCUIT DIAGRAM:

Ø In P-Spice:

4. OUTPUT RESPONSE:

Ø When Light is not falling on LDR:

· Voltage:-

· Current:-

Ø When Light is falling on LDR:

· Voltage:-

· Current:-

5. APPLICATIONS:

Ø Used in parking system. When the car comes near the gate of garage, the parking lamp glows and the gate opens as the light falls on the LDR and the current passes through the circuit.

Ø Security alarm

TRAFFIC LIGHT SYSTEM USING IC555

By Creative Engineering Projects on 12:29 in 2nd semester, 4017 decade counter, analog, engineering project, ic555, traffic light

Abstract:

Ø This project operates red, amber and green LEDs in the correct sequence for a single traffic light.

Ø The time taken for the complete red - red & amber - green - amber sequence can be varied from about 7s to about 2½ minutes by adjusting the 1M preset.

Ø The 555 Astable circuit provides clock pulses for the 4017 counter which has ten outputs (Q0 to Q9).

Ø Each output becomes high in turn as the clock pulses are received. Appropriate outputs are combined with diodes to supply the amber and green LEDs.

Ø The red LED is connected to the ÷10 output which is high for the first 5 counts (Q0-Q4 high), this saves using 5 diodes for red and simplifies the circuit.

Components used:

Circuit diagram:

Working of components:

· IC555:

Ø It works in 3 modes:

v Astable - producing a square wave

v Monostable - producing a single pulse when triggered

v Bistable - a simple memory which can be set and reset

v Buffer - an inverting buffer (Schmitt trigger)

Here in this project it is operated in Astable mode.

Astable State:

An astable circuit produces a 'square wave', this is a digital waveform with sharp transitions between low (0V) and high (+Vs). Note that the durations of the low and high states may be different. The circuit is called an astable because it is not stable in any state: the output is continually changing between 'low' and 'high'

v With the output high (+Vs) the capacitor C1 is charged by current flowing through R1 and R2. The threshold and trigger inputs monitor the capacitor voltage

v When it reaches ²/₃Vs (threshold voltage) the output becomes low and the discharge pin is connected to 0V.The capacitor now discharges with current flowing through R2 into the discharge pin.

v When the voltage falls to ¹/₃Vs (trigger voltage) the output becomes high again and the discharge pin is disconnected, allowing the capacitor to start charging again.

· 4017 decade counter:

Ø The count advances as the clock input becomes high (on the rising-edge). Each output Q0-Q9 goes high in turn as counting advances.

Ø Appropriate outputs are combined with diodes to supply the amber and green LEDs.

Ø The ÷10 output is high for counts 0-4 and low for 5-9, so it provides an output at ¹/₁₀ of the clock frequency.

Ø The red LED is connected to the ÷10 output which is high for the first 5 counts (Q0-Q4 high), this saves using 5 diodes for red and simplifies the circuit.

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