Wiring circuit

Showing posts with label 555. Show all posts

Tuesday, October 28, 2014

Transistor Checker with 555 Timer 4027IC

This regular circuit has helped me prohibited on many occasions. It is able to check transistors, inside the circuit, down to 40 ohms across the radio dish-foot otherwise base-emitter junctions. It can in addition check the output power transistors on amplifier circuits. Circuit company is because follows. The 555 timer ( IC1 ) is usual up as a 12hz multi vibrator. The output on pin 3 drives the 4027 flip-dud ( IC2). This flip-flop divides the input frequency by two and delivers complementary voltage outputs to pin 15 and 14. The outputs are connected to LED1 and LED2 through the current limiting resistor R3.

The LEDs are arranged so to facilitate what time the polarity across the circuit is lone way single one LED force light and what time the polarity reverses the other LED will light, therefore while rebuff transistor is connected to the tester the LEDs will alternately flicker. The IC2 outputs are too connected to resistors R4 and R5 with the junction of these two resistors connected to the immoral of the transistor being tested. With a proficient transistor connected to the tester, the transistor yearn for circle on and crop a passing across the LED duo. If a good NPN transistor is connected next LED1 will burst by itself and if a good PNP transistor is connected then LED2 will flash by itself. If the transistor is initiate both LEDs force flash and if the transistor is shorted at that moment neither LED will flash.

Thursday, October 23, 2014

LED Flasher Circuit Using 555 Timer IC

This is a simple LED flasher project that uses a common 555 timer IC for its operation. It is configured as an astable mode which means that its output is a square wave oscillator. Two LEDs are connected to its output in such a way that when one LED is ON, the other LED will turn OFF.

It uses only 10 simple parts that are easily available at any electronic shops. Capacitor C2 charges exponentially through resistors R1, R2 and the resistance of the trimpot. When C2 has charged to about 2/3 VCC it stops charging and it discharges to about 1/3 VCC through R2 and the trimpot resistance via pin 7. This is the standard operation of a 555 timer. When a Vcc of 5 V to 15 V DC is applied to the circuit, the LED will start to flash.

The frequency of the flashing can be changed by varying the resistance of the potentiometer or trimpot. Parts List The parts list of the simple LED project is as shown below.

Monday, October 20, 2014

On Demand WC Fan Using 555

In most WCs with an extractor the fan is connected to the lighting circuit and is switched on and off either in sympathy with the light or with a short delay. Since toilets are sometimes used for washing the hands or just for a quick look in the mirror, it is not always necessary to change the air in the smallest room in the house. The following circuit automatically determines whether there really is any need to run the fan and reacts appropriately. No odour sensor is needed: we just employ a small contact that detects when and for how long the toilet seat lid is lifted.

On-Demand WC Fan Using 555 circuit diagram

If the seat lid is left up for at least some presettable minimum time t1, the fan is set running for another presettable time t2. In the example shown the contact is made using a small magnet on the lid and a reed switch mounted on the cistern. The rest is straightforward: IC2, the familiar 555, forms a timer whose period can be adjusted up to approximately 10 to 12 minutes using P2. This determines the fan running time. There are three CMOS NAND gates (type 4093) between the reed switch and the timer input which generate the required trigger signal. When the lid is in the ‘up’ position the reed switch is closed.

Capacitor C1 charges through P1 until it reaches the point where the output of IC1a switches from logic 1 to logic 0. The output of IC1b then goes to logic 1. The edge of the 0-1 transition, passed through the RC network formed by C2 and R2, results in the output of IC1c going to logic 0 for a second. This is taken to the trigger input on pin 2 of timer IC2, which in turn switches on the relay which causes the fan to run for the period of time determined by P2. The circuit is powered from a small transformer with a secondary winding delivering between approximately 8 V and 10 V. Do not forget to include a suitable fuse on the primary side.

The circuit around IC1b and IC1c ensures that the fan does not run continuously if the toilet seat lid is left up for an extended period. The time constant of P1 and C1 is set so that the fan does not run as a result of lavatorial transactions of a more minor nature, where the lid is opened and then closed shortly afterwards, before C1 has a chance to charge sufficiently to trigger the circuit.

Circuit Source: DIY Electronics Projects

Saturday, October 18, 2014

555 timer Electronic roulette wheel Diagram Circuit

Using a simple voltage controlled oscillator a 555 timer IC and 4017 counter/divider IC can be designed a very wonderful electronic roulette wheel game.
This electronic circuit is a simple version of an electronic roulette game and is based on the 4017 IC which is a 10 stage decade counter/divider. It is driven by another versatile IC 555 configured as a voltage controlled oscillator (VCO).
The 555 timer is connected as an astable multivibrator . When the S1 switch is pressed, the capacitor C3 gets charged, also at this point of time a constant stable clock is fed to the 4017 IC and the LEDs at its outputs light up in a cyclic manner producing a revolving effect. Adjusting the VR1 (variable resistor ) the speed of revolving effect can be varied .
When the S1 switch is released, the main supply is cut-OFF, C3 discharges and forces the freely running astable to gradually stretch and slow down the time period of its output pulses so that eventually the oscillations stop within a stipulated time. In response to these dying pulses the “rotation” of the LEDs connected to the output of IC 4017 also slow down gradually and stops to select a random score marked on the board.

Depending on how long the S1 switch remains depressed score will always be selected in random order .
This electronic roulette wheel game must be powered from a simple 9 volt DC power supply

Friday, October 17, 2014

Extend Timer Range For The 555 Circuit Diagram

Anyone who has designed circuits using the 555 timer chip will, at some time have wished that it could be programmed for longer timing periods. Timing periods greater than a few minutes are difficult to achieve because component leakage currents in large timing capacitors become significant. There is however no reason to opt for a purely digital solution just yet. The circuit shown here uses a 555 timer in the design but nevertheless achieves a timing interval of up to an hour! The trick here is to feed the timing capacitor not with a constant voltage but with a pulsed dc voltage. The pulses are derived from the un smoothed low voltage output of the power supply bridge rectifier.

Extend Timer Range For The 555 Circuit Diagram

The power supply output is not referenced to earth potential and the pulsing full wave rectified signal is fed to the base of T1 via resistor R1. A 100-Hz square wave signal is produced on the collector of T1 as the transistor switches. The positive half of this waveform charges up the timing capacitor C1 via D2 and P1. Diode D2 prevents the charge on C1 from discharging through T1 when the square wave signal goes low. Push-button S1 is used to start the timing period. This method of charging uses relatively low component values for P1 (2.2 MΩ) and C1 (100 to 200 µF) but achieves timing periods of up to an hour which is much longer than a standard 555 circuit configuration.

Wednesday, October 1, 2014

Light Activated Switch Circuit Using IC 555

A very useful light activated switch circuit can be made by utilising a single 555 timer with its trigger and threshold inputs connected together.
The schmitt has a very low input current (1.5uA) and can directly drive a relay taking up to 200mA of current. The circuit shows a 555 schmitt being used to energise a relay when the light level on a photoconductive cell falls below a preset value; the relay energises when the voltage on pins 2 and 5 is greater than 2/3Vcc and de-energises when the voltage falls below I/3Vcc. This gives a hysteresis of 1/3Vcc, The circuit can be used in many other similar applications where a high input impedance and low out- put impedance are required with the minimum component count.

Sunday, August 31, 2014

LED Circuit with Timer 555

This circuit LED reproduces the first LED sequence at this time used by FISA on behalf of Formula single racing. It may perhaps be alive used with slot car sets (such for example HO shin up AFX/Life Like/Tyco sets) or else means of communication controlled cars. IC1, a 555 timer IC, is used as a watch pulse generator. Its output is fed via NAND gates IC2a and IC2c to IC3, a 4024 binary counter. IC2b inverts the O4 output of 4024 binary counter IC3. originally, IC3 is reset and all its outputs are low, together with O4, which causes IC2b to present-day a rational climax to the pin 8 input of IC2c which after that passes pulses from the 555 timer circuit to the clock input of the 4024. IC3 then begins together with.

Following the count has reached binary 1111, the subsequently pulse sends the O4 output of IC3 high, which disables IC2c and IC3 stops with. The four used outputs of IC3 are connected to a resistor ‘ladder’ which acts to the same degree a clear-cut digital to analog convert-er (DAC). As the count increases so does the voltage produced by the side of the top of the ladder and this is connected to the inverting inputs of four comparators inside IC4 (an LM339) and to IC5, which is a 741 op amp furthermore connected while a comparator.

The categorical inputs of the comparators are connected to the taps of a voltage dividing wall, with the drumming voltages settle on using VR1, a 100kO trimpot. As IC3 counts, the rising stepped voltage from the DAC ladder switches the comparators on clothed in sequence, preliminary with IC4d and working up to IC5. in the same way as both comparator is curved on, its pair off of LEDs is lit; former LEDs 1 & 2, next LEDs 3 & 4 and so on. as soon as all five pairs of LEDs are lit, the then pulse from IC1 moves the binary count of IC3 to 10000, so the DAC voltage drops back to zilch and all LEDs are extinguished. by the same spell, with too stops, for the reason that the area of high pressure on O4 causes IC2c to check extra gate pulses. The circuit in that case remains reserve until the counter is reset by urgent pushbutton switch S1. This allows a recent sequence to initiate.

Saturday, August 30, 2014

water triggered alarm system with 555 timer

You can use this schema for you water tank.then you can know before over flowing your tank.on the other hand you can use this schema as a rain detector then you can know before rain comes.so I suppose this would be a so useful schema for you

Thursday, August 28, 2014

LED Flasher Circuit Using 555 Timer IC

The frequency of the flashing can be changed by varying the resistance of the potentiometer or trimpot.Parts List The parts list of the simple LED project is as shown below.