Digital Volume Control Circiuit

This is great opportunity to you.Because you can convert your old radio set.into a radio set with digital volume control.Here When you push S1 it increases the volume and when you press S2 It decrease the volume




Note

# Use DS1669 Ic for this circuit

# Supply voltage is 4.5v to 8v

# give the output of this circuit for the amp circuit

Electronic bell

This is the basic theory of a electric bell.I think this so useful thing for you all.you can do changes when you make this circuit such as changing the turns of coil,Changing the power of this circuit etc.fix this on a wooden board. There should be a touch between A & B.enjoy this








Note

# give 6v power for this circuit
# Use thin coil for this
# Turn your coil around a nail but befor start to turn cover nail with a paper.

Laser Barrier Detector

This is some what different circuit.But this is so simple circuit.Some times some people have used some security systems by using lasers you can use this one for detect those beams.what you have to do is attaching more than 10 LDR for a stick when you walk send it before you.Then it will detect those barriers.








# supply 6v for this circuit.
# Don't use this one for unnecessary things.

Tracking Transmitter

This is a tracking transmitter.Normally we use these thing to track animals,Rc planes etc.The power of this one is about 3.7mA.This circuit can be operated by using 1.5V button cell.The operating frequency is FM 100Mhz .But if you want to use it between 108Mhz to 88Mhz you have to use Just spread the windings of the coil just a bit About 1/2 a millimeter .This is wonderful project. Have fun with this.













Note

#This is not long range one but you can get the maximum advantage
#supply 1.5 v
#Attach 12 inch antenna
#Search until mmmmh mmmmmh mmmmmh mmmmmh sound comes from your radio set

Nicad Battery Charger

This is so useful circuit for you .Because you can charge your Nicad Batteries by using this circuit.And the other advantage is this circuit is a low cost circuit.Try this.....





Note

#Use 2.4V,4.8V,9.6V Batteries to charge.

Knight Rider Light Circuit With 6 LEDs

Most of you ask about 6 LED bulbs Knight Rider circuit.So Here it is.You can attach this one for your car or van.Actually this is so attractive circuit.and This circuit operates with 6v.




Note

#IC 40017 data

Intercom Circuit for Factories

Here I have given a intercom circuit This circuit is most suitable for factories.Because These units have high quality.Only 2 wires are required to connect the units together.













Note

# Be careful when you work with 230v

Spy FM Transmitter circuit

This is so impotent circuit for us,Because we can use this circuit as a spy unit.This circuit can transmit signals about 30m.And the other important thing is the power of this circuit we can operate this circuit with 1.5v to 3v(1.8 mA at 1.5 Volts )





Note

# If you are unable to find the transistor here use these transistors Because here you can use equal transistors such as 2N2222A, BFxxx series, BC109B, C, and even well known BC238.

# Use 1.5v to 3v for this circuit.Don't supply more than 3v(3v can cover the max range 30m)

Christmas star with 40 LEDs

This is an ordinary LED circuit.Here you must be creative when you build this circuit.Really If you are creative you can make really really fantastic Christmas star.On the other hand you can use this for your Christmas tree even.





Note

# Use 6v for this circuit
# Use blue colour LEDs to get the maximum attraction.

Pulse Generator With NE 555

Most of time we have to use pulse generators.Here I have introduce a Pulse generator with NE555 IC.Normally we use this IC with lots of circuits.When you operate this circuit give 5v as the supply voltage because this IC works with that current But don't give more than 5v.




Note

If you want to know how you can attach this circuit with other circuits just see knight rider circuit

Stereo VU Meter Circuit (Sound level displayer)

We can use this sound level displayer circuit to improve the out look of your amplifier circuit or your Radio player.Actually this gives an unbelievable attraction for your amplifier set or radio set.There are ten LEDs, so It would be better....




Note

# Use 12v for this circuit
# The input of the circuit is connected to the speaker output of your audio amplifier
# The sound level can be adjusted by using 10k ohm VR

1.25V to 25V To DC power supply

This is a DC power supply circuit.This circuit is based on LM317 Variable Regulator.This Regulator needs at least 28v(DC).Then it will out put 1.25v to 25v DC.So I suppose this would be an important circuit for you all.



Note

# 5K ohm Change If you want to change the out put voltage
# This circuit supplies 1.3A.

AUTO fast battery charger for cars

This circuit is a fast and auto car charger circuit.By using this one you can charge your lead acid battery easily.After charging the battery this circuit will cut off the power to your battery. so this is very useful circuit for you.






Note

# use IC 7805 as power supply for this circuit
# LM311 control test volt battery.
# Use PCB To build your circuit.
# Be careful when you deal with 230v

Power supply failure alarm circuit

This is very useful circuit for you.Because through this circuit we will be able to know about a power failure.Here We have done some modification,it's nothing but this circuit doesn't want an extra power supply for the alarm circuit.Because after the power failure alarm circuit doesn't operate with out power,But here we have attached a capacitor so through that after the power failure this capacitor can operate the alarm circuit.After giving 5V to 15V power.Then tune VR1 till alarm goes on position to off position


Note

# Give 5v to 15v power supply for this circuit.
#Tune VR1 after giving power.

Relay Delay circuit

This is a relay delay circuit.By using this circuit we can delay the function though circuit gave the signal.That means there is some time to operate the relay after the signal which gave form the circuit.here you can get 6 second delay.But if you want more you can do it changing the value of capacitor.If you use 470uf it will delay 20 seconds.




Note

# Use 12v to operate this circuit.
#If you use this circuit for your vehicle Please cover this circuit properly.

9 second Visual Timer Circuit

This is very useful circuit for you,Because you all can use this timer for various purposes.And the impotent thing of this circuit is giving a visual signal through LEDs.This is 9 second timer.This operates with 12v power.So you can use this one as a timer for your vehicle.

Speaker as a mic circuit

This is wonderful circuit for you guys.because we can use a normal speaker instead of a mic.When the voice waves touch the speaker.Magnetic field is changed in it.As a result of that it releases small electric signal to the transistor and transistor increase it.you can make this one as a intercom too.Then you have to use two circuits for that.try this...

0 to 20 seconds timer

Most of people asked about a short time timer.So I decided to introduce you this one.Here The time is adjustable from 0 to about 20 seconds.you can chang the time of it by changing the C1 Capacitor.So try this..







Parts:

R1 1 Meg Pot

R2 10 K 1/4 Watt Resistor

D1,D2 1N914 Diodes

C1 10uf 16V Electrolytic Capacitor

C2 0.01uf Ceramic Disc Capacitor

U1 555 Timer IC

RELAY 9V Relay

S1 Normally Open Push Button Switch

Note

# Use R1 to chang the time of Timer
# By changing the C1 capacitor You can change the time of timer

230 V Christmas lights

Christmas is getting near so I thought to give you very useful circuit.The impotent thing of this circuit is it operates from 230v.Here Time to time two sets of 230v bulbs light up.Actually you can use this one for your Christmas tree or for your crib.you can attach 5w 12 bulbs for 1 side.This circuit needs three power supplies as 6v, 12v and 230v.To supply 12v and 6 v use 300mA power supply.You can change the speed of lights by using 1M preset.





Note

# Use High amp really
# Be careful when you work with 230v

Air Flow Detector

Here we have used an incandescent lamp as L1.When the bulb is getting heat the resistance will be increased.As air flows over the filament it cools down, thus lowering it's resistance.If you want to see the amount of air flow.You can use a meter for that..And I hope to give you HHO Technology so at that situation this circuit will be so usefull Still We do some test on it.






Parts:

C1 47uF Electrolytic Capacitor
R1 100 Ohm 1/4W Resistor
R2 470 Ohm 1/4W Resistor
R3 10k 1/4W Resistor
R4 100K 1/4W Resistor
R5 1K 1/4W Resistor
U1 78L05 Voltage Regulator
U2 LM339 Op Amp
L1 #47 Incandescent lamp with glass removed
D1 LED

Note

# You have to brake the lamp with out removing the filament.

Rain detector

People have to face to various problems because of not having proper way to know the rain before it comes.So through this circuit you can detect rain comes or not.When a small drop water falls on the sensor Circuit gives a sound.you can use this one for various purposes.As an example you can use this one to detect your over flowing water tank.And I myself have used this one for various things....





Parts

D1 1N4001 Silicon Diode
BZ1 12V Buzzer
R1 1K 1/4 W Resistor
R2 680 Ohm 1/4 W Resistor
S1 SPST Switch
SCR1 C106B1 SCR 106CY
SENSOR See Notes
MISC Board, Wire, Case, PC Board (For Sensor)

Low Voltage monitor

This is a circuit which can be used to monitor batteries or other electric equipments current problems.Here that current will be indicated through the sound and through the LED.So you all can check your low volt equipments easily.




Parts:

U1 LM339 Voltage comparator IC
D1 1N5233B Zener Diode
D2 LED
R1, R3 1K 1/4W Resistor
R2 5K Pot
BZ1 Piezo Buzzer
MISC Board, wire, socket for IC

Note

# This circuit can be operated with 9v to 12v

Christmas star

This is a circuit for your Christmas star.Here LEDS are fading gradually.And If you are creative you can make a wonderful creation through this circuit.And I hope to give you more Christmas circuits.So try this








Parts:

C1 1µF 63V Polyester Capacito

C2 100µF 25V Electrolytic Capacitor

D1-D4 etc 5 or 3mm. LEDs

IC1 LM358 Low Power Dual Op-amp

R1,R2 4K7 1/4W Resistors

R3 22K 1/4W Resistor

R4 1M 1/4W Resistor

R5 2M2 1/4W Carbon Trimmer

R6,R10,R11,R14,R15 10K 1/4W Resistors

R7,R8 47K 1/4W Carbon Trimmers

R9,R13 27K 1/4W Resistors

R12,R16 56R 1/4W Resistors

Q1,Q2,Q4 BC327 45V 800mA PNP Transistors

Q3,Q5,Q6 BC337 45V 800mA NPN Transistors

SW1 SPST miniature Slider Switch


Note

# If you dont like to use trimmers, suggested values for a 9V supply are:R4=3M9, R9 & R13=47K and trimmers replaced by a short.

# If you want to use 7 LEDs per strip R7 & R8 should be changed to 100K.and give 15v