Schematic Diagram: 555

Showing posts with label 555. Show all posts

Tuesday, November 18, 2014

Police Sirine Circuit with IC 555

The series of police sirens with 555 ic this is a series of sirens that utilizes two IC 555 as a pulse generator and producing shrill voice.

Both ic 555 respectively build the astable multivibrator circuit and generate output signals with different frequencies. It is intended to be used as one of the high frequency generator or a screeching sound and the other as a regulator of the swing from last shrill voice. If we observe the working principle of this circuit is very similar to a series of modulation fm. Where the shrill sound signal likened to a high frequency signal from the oscillator circuit and control signal swing is the wail of the information signal or input signals that will transmit. This is consistent with the shape of the output signal associated with the loudspeaker, which has an output signal frequency changes in the form of regular meetings wave tenuous.

Actually a series of sirens could be simpler than if you use a 556 IC which is a dual multivibrator or equal to two pieces of IC 555. IC 556 has two multivibrator circuit menfaatkan so you can meet the workflow of this siren sound-producing circuit. Or you can also make it by using a combination of multiple transistors. And it could be you do remember the oscillator circuit can be easily made with transistors.

Appropriate image above then:

R1, R2, and C1 is a determinant of the frequency of the signal generated by IC1

R3, R4 and C3 is a determinant of the signal frequency whine

Signals generated by IC1 IC2 pin 5 connected to the control signals intended for the resulting shrieks

Screeching sound signal will swing to follow the control of the output signal IC1

You can do experiments in order to gain more understanding of police sirens this circuit by changing the value of some critical components such as the frequency of R1, R2, R3, R4, C1 and C3.

Wednesday, November 12, 2014

using 555 timer ic White led driver circuit with explanation

A very simple white led driver electronic circuit project can be designed using this circuit diagram , that is based on a 555 timer circuit and some other electronic parts .
The 555 is capable of sinking and sourcing up to 200mA, but it gets very hot when doing this on a 12v supply.

This white led driver circuit shows the maximum number of white LEDs that can be realistically driven from a 555 timer . The total current was limited to about 130mA as each LED is designed to pass about 17mA to 22mA maximum. A white LED drops a characteristic 3.2v to 3.6v and this means only 3 LEDs can be placed in series.
As you can see in the circuit diagram , this electronic project circuit require few external electronic parts and is capable to drive up to 48 white LEDs from a 12 volts DC power source , utilizing few electronic components .

Thursday, October 16, 2014

555 IC Timed Beeper Circuit Diagram

This is a simple timed beeper circuit diagram of beeper using 555 timer. This circuit can be employed to energize lights, horn, or other signaling device at any desired interval when the mercury switch is triggered. Since the current handling capability of mercury switch is not so high, an SCR is used to handle current drawn by the 555 timer circuit. Chose the SCR current rating of 500mA at minimum to safely drive the 555 IC and the relay. The relay is not needed when the current drawn by alarm is less than 200mA, in this case the alarm can be installed to directly replace the relay coil. Here is the schematic diagram of the circuit.

555-IC Timed Beeper Circuit Diagram

Thursday, September 25, 2014

Simple Touch Operated Switch Circuit Diagram Using IC 555

The touch operated switch circuit basically comprises a touch activated mono- stable vibrator using an NE555 IC, which activates the TFL 7493 IC used as a bistable.

Transistor T2 is used to provide sufficient drive capability to drive the relay.
The power supply shown provides an appropriate DC voltage to drive a conventional relay. In the circuit, some special precautions have been taken to avoid interference pick-up, to which I`l`L ICs are especially prone. Capacitor C2 is rather large compared to the conventional value (0.01].tF) used in this position.
The extremal load is connected across the relay contacts.
This modification has proved quite effective. Another modification is the addition of Cl-RI parallel combination. The value of Rl is best chosen by trail and error, and is a compromise between sensitivity and immunity from stray pick·up, Its value lies in the range 1.8M to 1OM. R1 may be excluded altogether. An additional decoupling capacitor (0.01uF) may be added as close as possible to the supply terminals of IC 7493.
An LED with a suitable series resistance may be included in the circuit and placed in the center of the touch plate to indicate when the relay is activated. In cases of severe stray pick-up, the unit should be enclosed in a metal casing that should be grounded.
The prototype was constructed on a conventional bread board. To minimize stray pick-up, the interconnections should be as short as possible. If the unit is situated away from the touch sensor, a shielded wire should be used for the connection.
This causes a time delay before the load is actually activated. To avoid this, TI is introduced.
TI acts as an inverter and converts a rising edge into a falling edge.
The monostable is touch activated and it provides the triggering input to the bistable. However, the bistable triggers only on the falling edge of the monostable output pulse.

Tuesday, August 26, 2014

Relay Toggle Circuit Using a 555 Timer

This 555 timer schema below toggles a relay when a button is pressed. Pins 2 and 6, the threshold and trigger inputs, are held at 1/2 the supply voltage by the two 10K resistors. When the output is high, the capacitor charges through the 100K resistor, and discharges when the output is low. When the button is pressed, the capacitor voltage is applied to pins 2 and 6 which causes the output to change to the opposite state. When the button is released, the capacitor will charge or discharge to the new level at the output (pin 3). The parts are not critical, the resistors can be somewhat higher or lower, but the 2 resistors at pins 2 and 6 should be equal values, and the resistor connected to the cap should be 10 times greater or more.

Circuit diagram :

Relay Toggle Circuit Diagram

Advantages of this schema are the large hystersis range at the input which avoids false triggering, and only a few parts are needed for construction. One disadvantage is the relay may be engaged when power is first applied. To solve this problem, you could tie the reset line (pin 4) to another resistor/capacitor combination with the capacitor at ground and the resistor at the +V point. This will cause pin 4 to be held near ground for a short period which will reset the output when power is applied.

The 100 ohm resistor and 100uF capacitor serve to filter noise on the supply line if the schema is used in a automotive application. They may not be necessary. The schema may work well without those parts.

Saturday, August 16, 2014

DC to AC Inverter with 555 Wiring diagram Schematic

This schema is more of a DC to AC inverter, it uses a 555 IC as a low frequency oscillator, adjustable, adjustment can be done by the potentiometer R4 and frequency should be between 50-60 Hertz. The pulses from the IC 555 will go to Q1 and Q2 are amplified and sent to the transformer T1, which has its winding reversed. Capacitor C4 and coil L1 filter are the input to T1, it effectively ensures that a sine wave is formed.

DC to AC Inverter with 555 Circuit Diagram

List of components

R1 = 10K
R2 = 100K
R3 = 100 ohms
R4 = 50K potmeter
C1, C2 = 0.1μF
C3 = 0.01μF
C4 = 2700μF
Q1 = TIP41A, NTE196, ECG196
Q2 = TIP42A, NTE197, ECG197
L1 = 1μH
T1 = Transformer

Voltage Inverter using IC NE 555

In many diagram we need to generate an internal adjustable voltage. This schema shows how it is possible to use a trusty old NE555 timer IC and a bit of external schemary to create a voltage inverter and doubler. The input voltage to be doubled is fed in at connector K1. To generate the stepped-up output at connector K2 the timer IC drives a two-stage inverting charge pump schema.

The NE555 is configured as an astable multivibrator and produces a rectangular wave at its output, with variable mark-space ratio and variable frequency. This results in timing capacitor C3 (see schema diagram) being alternately charged and discharged; the voltage at pin 2 (THR) of the NE555 swings between one-third of the supply voltage and two-thirds of the supply voltage.

Voltage Inverter Circuit Using IC NE555

The output of the NE555 is connected to two voltage inverters. The first inverter comprises C1, C2, D1 and D2. These components convert the rectangular wave signal into a nega-tive DC level at the upper pin of K2. The second inverter, comprising C4, C5, D3 and D4, is also driven from the output of IC1, but uses the negative output voltage present on diode D3 as its reference potential. The consequence is that at the lower pin of output connector K2 we obtain a negative volt-age double that on the upper pin.

Now let us look at the voltage feedback arrangement, which lets us adjust this doubled negative output voltage down to the level we want. The NE555 has a control voltage input on pin 5 (CV). Normally the voltage level on this pin is maintained at two-thirds of the supply voltage by internal schemary. The voltage provides a reference for one of the comparators inside the device. If the reference voltage on the CV pin is raised towards the supply voltage by an external schema, the timing capacitor C3 in the astable multivibrator will take longer to charge and to discharge. As a result the frequency of the rectangle wave output from IC1 will fall, and its mark-space ratio will also fall.

The source for the CV reference voltage in this schema is the base-emitter junction of PNP transistor T1. If the base volt-age of T1 is approximately 500 mV lower than its emitter voltage, T1 will start to conduct and thus pull the voltage on the CV pin towards the positive supply.

In the feedback path NPN transistor T2 has the function of a voltage level shifter, being wired in common-base configuration. The threshold is set by the resistance of the feedback chain comprising resistor R3 and potentiometer P1. When the emitter voltage of transistor T2 is more than approximately 500 mV lower than its base voltage it will start to conduct. Its collector then acts as a current sink. Potentiometer P1 can be used to adjust the sensitivity of the negative feedback schema and hence the final output voltage level.Using T1 as a voltage reference means that the schema will adjust itself to compensate not only for changes in load at K2, but also for changes in the input supply voltage. If K2 is disconnected from the load the desired output voltage will be maintained, with the oscillation frequency falling to around 150 Hz.

A particular feature of this schema is the somewhat unconventional way that the NE555’s discharge pin (pin 7) is connected to its output (pin 3). To understand how this trick works we need to inspect the innards of the IC. Both pins are outputs, driven by internal transistors with bases both connected (via separate base resistors) to the emitter of a further transistor. The collectors of the output transistors are thus isolated from one another [1].

The external wiring connecting pins 3 and 7 together means that the two transistors are operating in parallel: this roughly doubles the current that can be switched to ground.The two oscilloscope traces show how the output voltage behaves under different circumstances. The left-hand figure shows the behaviour of the schema with an input voltage of 9 V and a resistive load of 470 Ω connected to the lower pin of output connector K2. The figure on the right shows the situation with an input voltage of 10 V and a load of 1 kΩ on the lower pin of output connector K2. The pulse width and frequency of the rectangle wave at the output of IC1 are automatically adjusted to compensate for the differing conditions by the feedback mechanism built around T1 and T2.

Because of the voltage drops across the Darlington out-put stage in the IC (2.5 V maximum) and the four diodes (700 mV each) the schema achieves an efficiency at full load (470 Ω between the output and ground) of approximately 50 %; at lower loads (1 kΩ) the efficiency is about 65 %.

Author : Peter Krueger - Copyright : Elektor