Showing posts with label Hobby Electronics. Show all posts
Showing posts with label Hobby Electronics. Show all posts
Friday, November 2, 2012
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.
Continue Reading here[...]
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.
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.
Continue Reading here[...]
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.
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:
Continue Reading here[...]
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.
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).
Continue Reading here[...]
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.
Digital Object Counter using LDR and digital IC 7490
This is the simple circuit on Hobby Electronics. In this circuit three modules are used in object counter. 555 timer are used as a monostable mode and astable mode. The other is counter module.
In this circuit 555 timer configured as a monostable mode, is a simple automatic dark sensor circuit that gives output when light falling is blocked on LDR. Pin 3 of monostable circuit has been connected to pin 4 of astable timer. When monostable circuit generates output, astable mode timer starts giving pulses to the counter module. Frequency for counter module is set up using R4, R3 and C2. 
Continue Reading here[...]
7490acts as a decade counter and 7447 uses the output of 7490
to display numbers on seven segment display. This circuit counts from 0
to 9. You can count 0 to 100 modifying counter module circuit. Just
adding few components as well as two counter ic, two display driver and two display. For count 0 to 100, comments on the comments box. You will get complete circuit.
The output will be: If you block light falling on LDR, the number on seven segment display will increase.
Wednesday, January 18, 2012
Dual Voltage Power Supply 12 Volt
This is the simple circuit diagram of Dual Voltage Power Supply. It is used for Misc… application. This circuit is called regulated power supply. For this reason the main component of this circuit is Regulator IC. It also needs few components to built. The regulator 7812 is the positive voltage regulator and 7912 is the negative voltage regulator.
It regulates voltage from 24Volt to 12 Volt (DC). The transformer input is 110Volt to 220Volt (AC) and the output must be between 12Volt to 24Volt (AC) and current must be 500mA. In this circuit some capacitors are used as a filter for removing repole.
Sunday, October 30, 2011
Simple AM Transmitter Circuit
AM transmitter circuit that can transmit your audios to your backyard.This circuit is designed with limited the power output to match the FCC regulations and still produces enough amplitude modulation of voice in the medium wave band to satisfy your personal needs. You will love this.
These components can be easily obtained from your old medium wave radio. Q1 is provided with regenerative feedback by connecting the base and collector of Q1 to opposite ends of the tank circuit. C2 ,the 1nF capacitance , couples signals from the base to the top of L1, and C4 the 100pF capacitance ensures that the oscillation is transfered from collector, to the emitter, and through the internal base emitter resistance of the transistor Q2 (BC 109) , back to the base again.
The resistor R7 has a vital part in this circuit. It ensures that the oscillation will not be shunted to ground trough the very low value internal emitter resistance, re of Q1(BC 109), and also increases the input impedance such that the modulation signal will not be shunted to ground.
Q2 is wired as a common emitter RF amplifier, C5 decouples the emitter resistance and unleashes full gain of this stage. The microphone can be electret condenser microphone and the amount of AM modulation can be adjusted by the 4.7 K variable resistanceR5.
Saturday, October 8, 2011
AM Receiver Circuit Diagram Using ZN414 IC
A.M. Antenna coil and MW gang connected in parallel. One common point of this parallel circuit connected to the IC ZN414 pin number 2.
Another common point of that parallel circuit connected with two resistors (100kΩ, 1kΩ) in series. A capacitor is connected with the common point of resistors (100kΩ, 1kΩ). A capacitor is connected in series with base of the transistor and the pin number 1 of the ZN414.
One end of the 10kΩ resistor is connected with the collector point of the transistor BC549 and another end is connected with the power supply +Vcc.
And one end of the 100kΩ resistor is connected with the collector and another end connected with base. 105pF capacitor is connected between collector and ground. Pin 3 of IC ZN414 and emitter of the transistor is connected to the ground.
Required Instrument
- IC ZN 414.
- Capacitor(105pF×1,104pF×2,103pF×1)
- MW Gang
- Resistor(100kΩ×2,10kΩ×1,1kΩ×1,470Ω×1)
- AM antenna
- Transistor(BC549)
Friday, September 23, 2011
AM Transmitter Circuit Diagram Using 741 Op-amp
AM transmitter is a circuit which can transmit message signal to modulated signal. This circuit is designed with limited power and the required power supply of the transmitter circuit is 9 Volt.
The circuit has three parts that is an audio amplifier, radio frequency oscillator and modulator circuit. The frequency oscillator is built with 741 Op-amp and related components. The carrier signal frequency and its amplitude can be varied using variable resistor accordance with VR1 and VR2 respectively. C1 and C2 are the main components to generate the carrier frequency.
Another part of the circuit is an audio amplifier circuit. The audio amplifier is built with 741 Op-amp and related components. A microphone is used to convert the voice signal to the audio signal which is feed to the op-amp’s inverting terminal. This audio signal is amplified by the op-amp. The amplified audio signal is filtered using the capacitor C7. This output is feed to the modulator circuit.
The main part of the AM transmitter is modulator circuit which is built with the transistor BC109. The carrier signal is feed to the base of transistor and the message / audio signal is also feed to the emitter of the transistor.
Here the required modulated signal is taken from the collector of the transistor which is feed to the output antenna.
Tuesday, August 30, 2011
Luggage Protector Circuit Using 555 Timer IC
The circuit is called protector alarm circuit to protect from the theft of your luggage or bags. This circuit is built electronically using 555 timer IC. The alarm will rise highly when the thin wire is cut off by the thief. The circuit configuration using 555 timer IC acts as a astable multivibrator which produce signal tone of frequency of about 1 KHz and produce sound like a shrill noise away the output speaker.
If you need to know 555 Timer configuration click here and download
IC’s 5number pin is directly connected to the power supply. 10k, 68k resistor and 0.01uf capacitor are connected to generate specific range of frequency like as 1KHz. You can change output frequency by changing the value of resistor and capacitor. Pin 1 is directly connected to the ground. Output is taken from pin 3. A 8Ohms speaker is connected to the output for alarm sound. Thin wire is connected as shown in figure.
The wire would be very thin copper like 36 SWG or higher. You can use one gage of normal wire. The driving voltage of the circuit is 5 Volt to 12 Volt.
Monday, August 29, 2011
Transistor AM Modulator Circuit Diagram
Modulation is the process of changing some characteristics (e.g. amplitude, frequency or phase) of a carrier wave in accordance with the intensity of the signal is known as modulation.
The figure shows the electronics circuit of a simple am modulator. It is essentially a CE amplifier having a voltage gain of A. The carrier signal is the input to the amplifier. The modulating signal is applied in the emitter resistance circuit.
The carrier ec is applied at the input of the amplifier and the modulating signal es is applied in the emitter resistance circuit. The amplifier circuit amplifies the carrier by a factor A, so that the output is Aes. Since the modulating signal is a part of the biasing circuit, it products low frequency variations in the emitter circuit. This in turn causes variations in “A”.
The result is that amplitude of the carrier varies in accordance with the strength of the signal. Consequently, amplitude modulated output is obtained across RL. It may be noted that carrier should not influence the voltage gain A; only the modulating signal should do this. To achieve this objective, carries should have a small magnitude and signal should have a large magnitude.
Wednesday, August 17, 2011
A.M Modulator Circuit Diagram
In amplitude modulation the amplitude of a high-frequency carrier is varied in direct proportion to the low-frequency (base-band) message signal. The carrier is usually a sinusoidal waveform that is,
C(t) = Ac . cos(
Where, is the carrier amplitude and fc is the carrier frequency.
The base-band signal or message signal is,
m(t) = Am . cos(
Where, Am is the amplitude of message signal and fm is the frequency of message signal.
Where, Am is the amplitude of message signal and fm is the frequency of message signal.
An amplitude modulation wave may thus be described in its most general form as the function of the time as follows,
S(t) = m(t)×c(t)
Friday, August 12, 2011
Mini Auto Charger Fan Circuit
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. Fan - 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.
Wednesday, July 6, 2011
Battery Charger Control Circuit
Battery charger control circuit is very useful now-a-days. You need not follow on battery charging or disconnect from ac power for avoiding over charge. This circuit is used to charge battery when the battery voltage drops below the minimum voltage that you want to connect it to a charger. When the battery voltage reaches the maximum voltage you want the charger to be connected.
Suppose that the application requires an inverting voltage level detector with hysteresis. That is V0 must go low when Ei goes above Vut and V0 must go high when Ei drops below Vlt. For this application, do not change the circuit or design procedure for the non-inverting voltage level detectors, simply add an inverting amplifier, or inverting comparator, to the output Vo.
Tuesday, June 21, 2011
Heat Sensor Circuit
This is the simple heat sensor circuit. It can be used to control any device using heat sensor. In this circuit a thermistor and a resistance is connected in series. This arrangement makes a potential divider circuit.
Here the thermistor is Negative Temperature Coefficient type. So when the room temperature is increased its resistance decreases simultaneously and more current flows through the resistor and the thermistor. We find more voltage at the junction of the resistor and the thermistor.
Our thermistor resistance value is 110 ohms. Suppose the resistance value becomes 90 ohms after heating the 110 ohms thermistor. Then the voltage across one resistor of the voltage divider circuit equals the ratio of that resistor’s value and the sum of resistances of the voltage across the series combination. This is the concept of voltage divider.
The final output voltage of the voltage divider circuit is now applied to the npn transistor (BC548) through the base resistor (3.3K ohms). Here the emitter resistor is replaced with a zener diode. Emitter voltage is maintained at 4.7volt with the help of zener diode. This voltage is used to compare voltage. Transistor conducts when base voltage is greater than the emitter voltage. Transistor conducts if it gets more than 4.7volt of base voltage. Then the circuit is completed through buzzer and it gives sound.
Monday, June 20, 2011
Active FM Antenna Amplifier of FM Booster
FM booster is one kind of a preamplifier which can be used to listen FM radio programs from distance FM stations clearly. The circuit comprises a common-emitter tuned RF preamplifier which tuned RF preamplifier wired around VHF/UHF transistor 2SC2570.
Serial | Parts Lists | Value |
1 | R1 | 27kΩ |
2 | R2 | 270Ω |
3 | R3 | 1kΩ |
4 | C1 | 5.6pF |
5 | C2 | 5.6pF |
6 | C3 | 1n |
7 | C4 | |
8 | C5 | 10pF |
9 | C6 | 0.1µF |
10 | VC1 | 22pF Trimmer capacitor |
11 | L1 | 1T FROM BOTTOM END |
12 | L2 | 3T, 20SWG 5mm DIA, AIR CORE |
13 | T1 | 2SC2570 |
Adjust input/ output trimmers (VC1/VC2) for maximum gain.
Wednesday, June 15, 2011
3 digits Digital Ammeter using Microcontroller
Digital Ammeter is needed to do any kind of electronics circuit making. It is very much useful who is interested in electronics projects. Now-a-days there are many kind of digital or analog ammeter which are found in the market. But if you make such kind of digital meter then you have no no bounds happy.The bellow circuit is digital Ammeter based on PIC16F684 and ACS712 current sensor. Here the measured ac/dc current will display on three digit 7-segment with resolution 100mA. In this project current sensor is ACS712ELCTR-30A-T . This circuit can measure the ac or dc current up to 30mA with 66mV/A output sensitivity.
The micro-controller PIC16F684 is used to read analog value from the ACS712 current sensor output and micro-controller convert to current and displaying on 7-segments display. For this circuit all 7-segment displays will be common anode type and it driven by PNP transistor BC557. Originally, this circuit is suitable for measuring DC current.
Remote Control Using the NE 555 and LM 567
Remote control circuit consists of two parts, one is transmitter and the other is receiver. A simple diagram is schematic remote control. The transmitter circuit’s transmitter IC is controlled by NE555. Receiver circuit works by the signal emitted frequency which is emitted by that transmitter circuit. Transmitted signal frequency must be equal to the frequency decoder of the receiver circuit. The NE 555 generated frequency is same that receive frequency of IC LM 567.
The output frequency of the transmitter circuit is f,
f = 1.44/(Ra+2Rb)C
f = 1 / (1.1 xR1xC1)
This frequency depends on the value of R1 and C1.
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