water level indicater with circuitdiagram

Dancing Light using 555 Timer:

                                                                 A dancing light can be easily constructed using a 555 timer wired in astable mode. Please read the article Astable Multivibrator using 555 Timer before continuing. This circuit blinks two LEDs alternatively with some delay and it can be easily modified to include more LEDs or for controlling incandescent lamps. Time period of oscillation is determined by RC time constant of the circuit.

Circuit Diagram:

 

1^st and 8^th pins of 555 timer are used to provide power, Vcc and GND respectively. 4^th is the Reset pin which is a active low input and is tide to Vcc to avoid accidental resets. 5^th is the Control Voltage pin which is not used in this application, hence it is grounded via 0.01μF capacitor to avoid high frequency noises. When the output is HIGH capacitor charges to Vcc via resistor R1 and Diode. When the output is LOW capacitor discharges via resistor R2 and Discharge pin (7^th) of 555 timer.

When the output is LOW (0V) upper LED glows and when the output is HIGH (5v)  lower LED glows. Instead of current limiting resistors R3, R4 you may use another LED, such that two LEDs will come in series. You can use higher supply voltages if you need to drive more LEDs. LM/NE555 can work upto 16V and SE555 can work upto 18V. 555 can source or sink up to 200mA current, if you need more current use a transistor driver. You can also connect this circuit to relay for controlling incandescent lamps as shown below.

 

Here transistor is wired as a switch, when the base input is HIGH transistor turns ON and the relay is energized. Since the output of the 555 timer is square wave, the relay energizes and de-energizes continuously. Incandescent lamps turns ON alternatively since they are connected to Normally Open (NO) and Normally Closed (NC) of the realy output.

LED ON – OFF period is determined by the resistors R1, R2 and the capacitor C1. You can change these resistors or capacitors to adjust the time period and can be determined by the equation, T = 1.1RC.

Since the capacitor charges through R1, charging time period,
T_charging = T_HIGH = 1.1R1C1
Since the capacitor discharges through R2, discharging time period,
T_discharging = T_LOW = 1.1R2C1

Our 555 Astable Design Tool at the bottom of the article Astable Multivibrator using 555 Timer will make your calculations simpler.

 

 

how can i make a laser security system for home

Home security alarm system circuit diagram

Have you ever thought about implementing your own home security alarm systems? It’s one of the simplest and interesting circuits for electronic beginners. Our new home security equipment uses a LDR (Light Depended Resistor) to detect security problems. Theft attempt and other security threats can be controlled by using this simple circuit to improve your security systems. This is also best suited for school students for their high school project.

To implement this alarm system for home, you have to provide an optical path (with LASER beams) around your home. The LASER path is made possible with one LASER torch and 3 mirror arrangements which encloses the whole area. Please refer the project arrangement sectionbelow to make this optical (light) path. We have explained about home security system in detail with animation/ simulation.

Circuit diagram of Home security alarm:

 

 WORKING:

• This circuit is based on LDR (Light Depended Resistor), a variable resistor in which the resistance varies according to the light intensity falling on it.

• The LDR and resistor R1 forms a potential divider network, which is the main part of our security alarm circuit.

• We have already discussed about how transistor act like a switch, the same principle is used here.

• The voltage drop across the LDR is used to drive the transistor switch. When the voltage drop is above cut in voltage (0.6V), the transistor is turned ON.

• LDR has low resistance (mΩ range) in the presence of light and high resistance (MΩ range) in the absence of light.

• In our security alarm, a LASER light is allowed to fall on the LDR continuously using 3 mirrors (see the project arrangement figure).

• Light from other sources should not be allowed to fall on the LDR, so place the LDR in a box with a single hole to pass LASER.

• In this situation, the resistance offered by LDR is too low, since the LASER light is continuously allowed to fall on the LDR  surface.

• Thus the voltage drop across the LDR is also low [V=IR (Ohm’s law)] which is insufficient to turn ON the transistor, so the transistor remains in OFF state.

• When a person (eg: thief) makes a block to the continuous flow of LASER beam, then the light falling on the LDR gets blocked. Thus its resistance increases to a high value in the order of MΩ range (According to Ohm’s law V=IR).

• While resistance increases the voltage drop also increases, when this voltage drop exceeds the cut in voltage of the silicon NPN transistor (0.6V; BC547), it will turn ON.

• Then current from Vcc starts flowing to ground via the buzzer and transistor, which makes the beep sound.

• The beep sound from the security alarm gives the indication of some security failures.

Simulation (animation) of the project

To realize the concept we are providing animation/ simulation of home security alarm circuit below. For animated demonstration, LED is used instead of buzzer.

how can i make a portable mobile charger by 9v battery

You can make your own portable mobile charger by 9v battery

BT1=battery connector
K1.1=switch
C1=100uf capacitor
U1=5v voltage regulator
D2= rectifying Diode
C2=220uf capacitor
R1=150ohm resistor
D1=led
R2=330ohm resistor
R3=10kohm resistor
Female usb port

Here is a list of things you need to build the Portable USB Power Supply
1-battery connector
1-switch
1-100uf capacitor
1-5v voltage regulator
1-rectifying Diode
1-220uf capacitor
1-150ohm resistor
1-led
1-330ohm resistor
1-10kohm resistor
1-female usb port
1-pcb board
1-9v battery
1-project box

 Female usb port points:

 

                                              

solder your compoent in this arrangement and enjoy your mobile batterylife if yoy want to make it at rechargable battery than you can change it by battery

its hap and casing becomes like that