Automatic room light controller

This
circuit is called the auto circuit which can use any electronic device
to operate it automatically. To make this circuit the cost is very low.
Any interested student can make it very easily. The main component of
this circuit is transistor. Its operation is very easy. 

The
main purpose of this is to operate a charger fan where need 6volt
battery. This circuit is mainly needed when the main power is OFF. That
is called load shedding. Because at the time of  load shedding , 6volt
battery operate the fan automatically. You don’t have need to ON the
switch of the fan or OFF the fan switch. Only relay work this as a
switch. The charging system is also automatically. On the other big
matter is that no over charge is occurred of the battery. So the life
time of the battery is increased.

Component:

1.      Transistor ( npn ) – 2N2222, BC547

2.      Zener Diode - 6.8V

3.      Diode

4.       Relay - 6V

5.      Resistor – 1K, 100Ω

6.      Rechargeable Battery - 6V

7.      Bulb - 6V

8.      Power supply - 6V

Operation:

This
circuit is three section, input section and output section. 2N2222
transistor is used to control relay. BC547 transistor is used to control
output section using relay. Zener diode and a diode connect with BC547
transistor base as a series connection. Zener diode always controls
battery charge. It zener voltage is 6.8V which can’t overcome battery
voltage.

When
power supply voltage is applied to the 2N2222 transistor base the
transistor is on. So the relay is ON relatively the output circuit is
OFF. Inverse will occurs when power supply voltage is OFF. When 2N2222
transistor is ON then relay active only battery charging, relay
deactivate the fan. Zener diode always keeps battery voltage full
(6volt).

Advantages:

1.      Need not switch ON/OFF.

2.      It depends on AC power supply come or gone.

3.      This circuit is used when you are sleeping.

4.      Easy to make

5.      Cost is very low

6.      Components are few.

7.      Battery can’t over charge.

8.      Overall efficiency is 78%.

9.      Not you, only relay can do your work.

10.  The circuit is a small project for all students.

 

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Room Noise Detector Schematic Circuit

This circuit is intended to signal, through a flashing LED, the exceeding of a fixed threshold in room noise, chosen from three fixed levels, namely 50, 70 & 85 dB. Two Op-amps provide the necessary circuit gain for sounds picked-up by a miniature electret microphone to drive a LED. With SW1 in the first position the circuit is off. Second, third and fourth positions power the circuit and set the input sensitivity threshold to 85, 70 & 50 dB respectively. Current drawing is 1mA with LED off and 12-15mA when the LED is steady on.

Circuit diagram :

Room Noise Detector Circuit diagram

Parts List :

R1____________10K 1/4W Resistor
R2,R3_________22K 1/4W Resistors
R4___________100K 1/4W Resistor
R5,R9,R10_____56K 1/4W Resistors
R6_____________5K6 1/4W Resistor
R7___________560R 1/4W Resistor
R8_____________2K2 1/4W Resistor
R11____________1K 1/4W Resistor
R12___________33K 1/4W Resistor
R13__________330R 1/4W Resistor

C1___________100nF 63V Polyester Capacitor
C2____________10µF 25V Electrolytic Capacitor
C3___________470µF 25V Electrolytic Capacitor
C4____________47µF 25V Electrolytic Capacitor

D1_____________5mm. Red LED

IC1__________LM358 Low Power Dual Op-amp

Q1___________BC327 45V 800mA PNP Transistor

MIC1_________Miniature electret microphone

SW1__________2 poles 4 ways rotary switch

B1___________9V PP3 Battery

Clip for PP3 Battery

Use :

• Place the small box containing the circuit in the room where you intend to measure ambient noise.
• The 50 dB setting is provided to monitor the noise in the bedroom at night. If the LED is steady on, or flashes bright often, then your bedroom is inadequate and too noisy for sleep.
• The 70 dB setting is for living-rooms. If this level is often exceeded during the day, your apartment is rather uncomfortable.
• If noise level is constantly over 85 dB, 8 hours a day, then you are living in a dangerous environment.

Source by : Streampowers

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Amplifier circuit for small room

Amplifier circuit is very suitable to be used or applied in a narrow space such as in cars and so forth. Voltage amplifier is needed starting from 9 Volts to 17 Volts maximum. This amplifier circuit uses IC MPC575C, andsimilarities NEC575 . Power output is relatively very small, only 2 Watts.

Schematics Amplifier MPC575C

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