4017 LED Knight Rider Running Light Circuit Diagram

In this  4017 Knight Rider circuit, the 555 timer is wired as an oscillator. It can be adjusted to give the desired speed for the display. The output of the 555 is directly connected to the input of a Johnson Counter (CD 4017).

 The input of the counter is called the CLOCK line. The 10 outputs become active, one at a time, on the rising edge of the waveform from the 555. Each output can deliver about 20mA but a LED should not be connected to the output without a current-limiting resistor (220Ω in the circuit above).

The first 6 outputs of the chip are connected directly to the 6 LEDs and these “move” across the display. The next 4 outputs move the effect in the opposite direction and the cycle repeats. The animation above shows how the effect appears on the display. Using six LEDs, the display can be placed in the front of a model car to give a very realistic effect. The outputs can be taken to driver transistors to produce a larger version of the display.

Mobile Incoming Call Indicator Circuit Diagram

This circuit can be used to escape from the nuisance of mobile phone rings when you are at home. This circuit will give a visual indication if placed near a mobile phone even if the ringer is deactivated.

When a call is coming to the mobile phone, the transmitter inside it becomes activated. The  frequency of the transmitter is around 900MHz.The  coil L1 picks up these oscillations by induction and feds it to the base of Q1. This makes the transistor Q1 activated.Since the Collector of Q1 is connected to the pin 2 of IC1 (NE555) , the IC1 is triggered to make the LED connected at  its output pin (pin 3) to blink. The blinking of the LED is the indication of incoming call.

Notes:

•    The coil L1 can be made by making 150 turns of 36 SWG enameled copper wire on a 5mm dia   plastic former.Or you can purchase a 10 uH coil from shop if available.
•     The circuit can be powered from a 6V battery.
•     Assemble the circuit on a good quality PCB.
•     C1 & C3 are to be polyester  capacitors.
•     The electrolytic capacitor C2 must be rated 10V.

Automatic Street Light Controller Circuit Diagram

This circuit is an automatic street light controller. Sensors used to detect changes in light is LDR (Light dependent resistor), the working principle of Light dependent resistor is exposed to light when the resistance value of LDR great, but if not exposed to light or dark then the resistance value of LDR.

LDR is a special type of resistance whose value depends on the brightness of the light which is falling on it. It has resistance of about 1 mega ohm when in total darkness, but a resistance of only about 5k ohms when brightness illuminated. It responds to a large part of light spectrum.

When light falls on the LDR then its resistance decreases which results in increase of the voltage at pin 2 of the IC 555. IC 555 has got comparator inbuilt, which compares between the input voltage from pin2 and 1/3rd of the power supply voltage. When input falls below 1/3rd then output is set high otherwise it is set low. Since in brightness, input voltage rises so we obtain no positive voltage at output of pin 3 to drive relay.

Complete Room Securty System Circuit diagram

This simple circuit is called room security system circuit. The main purpose of this circuit is to secure your room in night. You need not any security guard. When any unwanted person wants to enter your room in night then this circuit raised alarm. On the other benefit, it is always activated on load shedding. 

There are five separates parts in this circuit – regulated power supply, relay driver, door switching, alarm system and audio amplifier. First section is regulated power supply. The output of IC 7809 is regulated +9Volt which is converted from 9Volt unregulated power supply. Capacitors are used for removing ripple. A full wave 9 volt transformer is connected in the input of this power section.

The second part is relay driver. Q1 transistor is used for driving relay. When the Q1 transistor is forward bias then the relay is ON and the total circuit gets positive voltage from ac source. In the time of load shedding relay is deactivated and the total circuit gets power from 6Volt Battery.

The third part is door switching. When C1 capacitor’s two terminals are short, transistor Q2 is reversed biased. So Q2 transistor is OFF. When C1 capacitor’s two terminals are open, transistor Q2 is forward biased. So Q2 transistor is ON. For this reason IC UM66 is ON and it generates music which is feed another two transistors Q3 and Q4. A speaker is connected with collector of the transistor Q4 as circuit diagram.

Freeze Protector Circuit

This is the simple freeze protector circuit diagram. It is also called timing circuit. It is just hobby project for beginners. When you need to operate automatically any device in the fixed time later after coming AC power supply, you can use this circuit. 

The voltage amplitude is high when AC power come. Suddenly high voltage destroys the electronics device. For this reason, in the time of load shedding we need to switched off electronics device (Audio/Video player, CD/DVD Player, TV, Freeze or any electronics device). This circuit solve this problem.

Hobby Electronics helps the beginners to know the timing circuit specially using 555 IC timer. NE555 IC is the very simple well known parts. Its configuration is very simple. You can use this timer any simple circuit. 

In this circuit use 12volt power supplies. 300k variable resistor is used for timing control. Timing resistor and capacitor are 300k and 1000uF. Only change the value of the variable resistor for your required timing. 

The circuit output pin 3 is connected with resistor (10k) and output 12 volt relay. Relay is connected as figured with the device. Making cost is too low. Anyone can make this circuit easily.