Identify diagram: circuit

Showing posts with label circuit. Show all posts

Showing posts with label circuit. Show all posts

Friday, 19 September 2014

Burglar Alarm With Timed Shutoff Circuit Diagram

This is a Burglar Alarm With Timed Shutoff Circuit Diagram. When SI (sensor) is closed, power is applied to U2, a dual timer. After a time determined by C2, CI is energized after a predetermined time determined by the value of C5, pin 9 of U2 becomes low, switching off the transistor in the optoisolater, cutting anode current of SCR1 and DE-energizing Kl. The system is now reset. Notice that (i6x C2) is less than (R7xC$). The ON time is approximately given by:(R7xC5)-(R6xC2) = Ton

Burglar Alarm With Timed Shutoff Circuit Diagram

Burglar Alarm With Timed Shutoff Circuit Diagram

Simple Inverse Scalier Circuit Diagram

Simple Inverse Scalier Circuit Diagram. If a DAC is operated in the feedback loop of an operational amplifier, then the amplifier gain is inversely proportional to the input digital number or code to the DAC.The version giving scaling inversely proportional to positive voltage is shown.

Simple Inverse Scalier Circuit Diagram

Friday, 6 June 2014

Crystal Controlled Reflection Oscillator Circuit Diagram

How to build a Crystal-controlled-reflection-oscillator circuit diagram . This is a simple crystal controlled reflection oscillator circuit, this unit is easily tunable and stable, consumes little power, and costs less than other types of oscillators tlmt operate at the same frequencies. This unusual combination of features is made possible by a design concept that includes operation of the transistor well beyond the 3 dB frequency of its current-versus- frequency curve.

Crystal Controlled Reflection Oscillator Circuit Diagram

Crystal Controlled Reflection Oscillator Circuit Diagram

The concept takes advantage of newly available crystals that resonate at frequencies up to about 1 GHz.The emitter of transistor Q is connected with variable capacitor Cl and series-resonant crystal X. The emitter is also connected to ground through bias resistor Rl. The base is connected to the parallel combination of inductor L and capacitor C3 through DE-blocking capacitor and C4 and is forward biased with respect to the emitter by resistors R3 and R4.

Impedance Z could be the 220-0 resistor shown or any small impedance that enables the extraction of the output signal through coupling capacitor C2. If Z is a tuned circuit, it is tuned to the frequency of the crystal.

Digital Frequency Comparator Circuit Diagram

Here’s a digital frequency comparator for oscillators that indicates the result through a 7-segment display and a light-emitting diode (LED). When the frequency count of an oscillator is below ‘8,’ the corresponding LED remains turned off. As soon as the count reaches ‘8,’ the LED turns on and the 7-segment display shows ‘8.’

This demo circuit uses two NE555 timers configured as astable free-running oscillators, whose frequencies are to be compared.

The circuit of the digital frequency comparator portion comprises two 74LS90 decade counter ICs (IC2 and IC6), two 74LS47 7-segment display driver ICs (IC3 and IC7), 74LS74 set/reset flip-flop (IC4), 74LS00 NAND gate (IC8) and two 7-segment displays (DIS1 and DIS2). The astable free-running oscillators built around the timers are the frequency sources for the corresponding counters.

Digital Frequency Comparator Circuit Diagram

When power supply to the circuit is switched on, timing capacitor C1 starts charging through resistor R1 and potmeter VR1. When the capacitor voltage reaches 2/3Vcc, the internal comparator of IC1 triggers the flip-flop and the capacitor starts discharging towards ground though VR1. When the capacitor voltage reaches 1/3Vcc, the lower comparator of IC1 is triggered and the capacitor starts charging again. The charge-discharge cycle repeats. That means, the capacitor charges and discharges periodically between two-third and one-third of the power supply (Vcc). The output of NE555 is high during charging and low during discharging of capacitor C1.

The other oscillator (IC5) works similarly. The oscillator frequency can be varied by the potentiometer (VR1 or VR2). Output pins (pin 3) of the oscillators (IC1 and IC5) are connected to the respective decade counters (IC2 and IC6) through the DPDT switch.

IC2 and IC6 count the initial eight cycles. IC 74LS90 is a 4-bit ripple decade counter. It consists of a divide-by-two section and a divide-by-five section counter. Each section has a separate clock input. The input of the divide-by-five section (CP1) is externally connected to the P output (pin 12) of the divide-by-two section (CP0). When the divide-by-two section receives clock pulse, it becomes a divide-by-ten counter.

Decade counter 74LS90 is reset by a high pulse at its pins 2 and 3. Initially, pins 2 and 3 are pulled down by resistor R2. The P through S outputs of IC2 are connected to the A through D inputs of IC3. Pin 11 (S) of IC2 is also connected to pin 3 of IC4(A) for providing the clock pulse. The count is displayed on the 7-segment display.

The 7-segment decoder/driver (74LS47) accepts four binary-coded decimals (8421), generates their complements internally and decodes the data with seven AND/OR gates having the open-collector output to drive the display segments directly. Each segment-driver output is capable of sinking 40mA current in the ‘on’ state. Pins 3, 4 and 5 of the display driver are connected to Vcc to disable the ripple-blanking input (RBI), blanking input (BI)/ripple-blanking output (RBO) and lamp test (LT).

IC3 provides segment data to the 7-segment display through current-limiting resistors R3 through R9 (each 220 ohms).

IC 74LS74 (IC4) controls the reset pin (RST) of NE555. It is a dual D-type flip-flop with direct clear and set inputs and complementary outputs. The input data is transferred to the outputs on the positive edge of the clock pulse. Since the Q output is connected to the data input D, the flip-flops work in toggle mode.

Initially, reset pins 1 and 13 of the flip-flops are pulled high via resistor R10. When the reset pin of any flip-flop receives a low pulse from NAND gate N2 of IC8, the flip-flop is reset and its Q output goes high. On receiving a clock pulse, the Q and Q outputs of the flip-flop go high and low, respectively, and the LED turns on. The low output of IC4 resets the oscillators. The reset signal is derived with the help of NAND gates N3 and N4.

When switch S2 is pressed, both the oscillators and the respective counters start working. As soon as any of the counters counts ‘8,’ the corresponding display shows ‘8’ and LED glows. This means that oscillator has a higher frequency. Now both the counters stop counting because the flip-flop output goes low to reset both the astable oscillators.

In case the frequencies of both the stable oscillators are same, both the displays show ‘8’ and LED1 and LED2 glow at the same time.

Sourced By EFY Author V. Gopalakrishnan

Wideband Wien Oscillator Circuit with Single Gang Pot

This Wien bridge oscillator (after Max Wien, 1866–1938) produces a low-distortion sine wave of constant amplitude, from about 15 Hz to 150 kHz. It requires just four opamps and will work off a single 9-volt battery. Also, unlike most Wien bridge oscillators, it does not require a dual-gang potentiometer for tuning. Op amp IC2b provides an artificial ground so that the circuit will operate from a unipolar supply (9 V battery or power pack). IC2a is the main amplifier for the oscillator. The frequency range is divided into four decades by 2-pole, 4-way rotary switch SW1.

Wideband Wien Oscillator Circuit with Single-Gang Pot Circuit Diagram

Wideband Wien Oscillator Circuit with Single-Gang Pot Circuit Diagram

Only one arm of the Wien network is varied, but the change in positive feedback that would normally result is compensated for by IC1b, which works to bootstrap R2, thereby changing the negative feedback enough to maintain oscillation. A linear change in the resistance of the tuning pot results in a roughly logarithmic change in frequency. To get a more conventional linear change a log-taper pot is used wired so that rotating the knob anticlockwise causes frequency to increase.

You could use an anti-log pot the other way around if you prefer, but these things are notoriously hard to find. IC1A is an integrator that monitors the amplitude of the output signal and drives an LED (D2). This must be mounted facing the LDR (light dependent resistor) and shielded from ambient light (for example, with a piece of heat-shrink tubing). IC1a is then able to control the gain of IC2a so that oscillation is maintained with minimum distortion.

The maximum output amplitude of the generator is about 2 Vp-p when the LED and LDR are mounted as close as possible. Distortion is less than 0.5 % in the lowest range, and too low for the author to measure in the higher ranges. Any LDR should work, provided its dark resistance is greater than 100 kO. If you do not have an LDR with such high resistance, try increasing R5 until oscillation starts. Breadboarded prototypes of the circuit were built by the author using dual and quad opamp packages, and both work equally well.

Author: Merlin Blencowe (Elektor)

Resistors:
R1,R2,R3,R6,R10,R11 = 10kO
R7 = 100kO
R4,R9,R12 = 100O
R5 = 12kO
R8 = 1kO
P1,P2 = 10kO potentiometer, logarithmic law
R13 = LDR, R(dark) >100kO, e.g. Excelitas Tech type
VT90N1 (Newark/Farnell # 2568243)

Capacitors:
C1,C5 = 1µF solid
C2,C6 = 100nF
C3,C7 = 10nF
C4,C8 = 1nF
C9-C12 = 47µF 16V, electrolytic, radial

Semiconductors:
D1,D2,D3 = 1N4148
D4 = LED, red, 5mm
IC1,IC2 = TL072ACP

Miscellaneous:
SW1 = 2-pole 4-position rotary switch, C&K Compo-
nents type RTAP42S04WFLSS
K1,K2 = PCB terminal block, 5mm pitch

Wednesday, 12 June 2013

AC Motor Speed Controller Circuit With explanation

This AC motor speed controller can handle most universal type (brushed) AC motors and other loads up to about 250W. It works in much the same was a light dimmer circuit; by chopping part of the AC waveform off to effectively control voltage. Because of this functionality, the circuit will work for a wide variety of loads including incandescent light bulbs, heating elements, brushed AC motors and some transformers. The circuit tries to maintain a constant motor speed regardless of load so it is also ideal for power tools. Note that the circuit can only control brushed AC motors. Inductive motors require a variable frequency control. AC Motor Speed Controller Circuit

AC Motor Speed Controller Circuit

Parts

Part	Total Qty.	Description	Substitutions
R1	1	27K 1W Resistor
R2	1	10K 1/4W Resistor
R3	1	100K 1/4W Resistor
R4	1	33K 1/4W Resistor
R5	1	2.2K 1/4W Resistor
R6	1	1K 1/4W Resistor
R7	1	60K Ohm 1/4W Resistor
R8	1	3K Linear Taper Trim Pot
R9	1	5K Linear Taper Pot
R10	1	4.7K Linear Taper Trim Pot
R11	1	3.3K 1/4W Resistor
R12	1	100 Ohm 1/4W Resistor
R13	1	47 Ohm 1W Resistor (See Notes)
C1, C3	2	0.1uF Ceramic Disc Capacitor
C2	1	100uF 50V Electrolytic Capacitor
D1	1	6V Zener Diode
Q1	1	2N2222 NPN Transistor	2N3904
SCR1	1	ECG5400
TR1	1	TRIAC (See Notes)
U1	1	DIAC Opto-Isolator (See Notes)
BR1, BR2	2	5A 50V Bridge Rectifier
T1	1	Transformer (See Notes)
MISC	1	PC Board, Case, Line Cord, Socket For U1, Heatsinks

Notes

TR1 must be chosen to match the requirements of the load. Most generic TRIACs with ratings to support your load will work fine in this circuit. If you find a TRIAC that works well, feel free to leave a comment.
U1 must be chosen to match the ratings of TR1. Most generic DIAC based opto-isolators will work fine. If you have success with a specific part, feel free to leave a comment.
T1 is any small transformer with a 1:10 turns ratio. The circuit is designed to run on 120V so a 120V to 12V transformer will work. Alternately, you can wind T1 on a transformer core using a primary of 25 turns, a secondary of 200 turns, and 26 gauge magnet wire.
R9 is used to adjust motor speed. R10 is a trim pot used to fine tune the governing action of the circuit. R8 fine tunes the feedback circuit to adjust for proper voltage at the gate of SCR1. It should be adjusted to just past the minimum point at which the circuit begins to operate.
R13 must be chosen to match the load. Generally, larger loads will require a smaller value.
Since this circuit is not isolated from mains, it must be built in an insulated case.

Source: aaroncake.net

Wednesday, 29 May 2013

Simple delay circuit Diagram

This is simple delay circuit.When you change the value of cap the time delay will be changed.I suppose beginners can learn a lot from this circuit and this circuit gives you to build or fix new circuits.

Note

# This circuit can be operated with 4.5V power supply

Tuesday, 28 May 2013

1 5V LED Flasher Circuit Diagram

This is so simple circuit diagram.you can power this circuit with 1.5V power supply.To get maximum results please build this on a PCB

Monday, 27 May 2013

Inverted Relay Driver Stage Circuit

An inverted relay driver stage circuit design was requested to me by Mr Aparajit for some specific functioning of the relay, lets know the whole procedure of making the said circuit.

Request made by Mr. Aparajit:

Dear Sir,
 
I want to interface a Relay with 8051 microcontroller and its
operating voltage is 5v.
A single BC547 (in Common emitter) Transistor driving a 12v Relay.
 
At initial Power-on all output of microcontroller are logic high(+5v).
Even I initialize its output to logic Low(0v) it takes a fraction of
second to change state. Which resulting a fluctuation at Relay and its
output.
 
So, I want to design a inverted Circuit to drive that relay. i.e Input
logic 0v to ON, logic high(5v) to OFF the Relay.
I have used NOT-GATE like 74hc04, results are perfect, but i need a
small transistor based solution.
 
 
 
Thanks for responding.
 
Regards,
Aparajit.

My Reply to Mr. Aparajit

Hello Aparajit,

Either you can use a PNP transistor like a BC557 
in place of BC547 and connect the relay across its collector and 
ground, or,.... connect another BC547 with the existing one in the 
following way:

The relay driver BC547s base resistor end which 
was previously connected to the microcontroller o/p now gets connected 
to the collector of the new BC547. This junction also gets connected to 
the positive via a 2K2 or nearby value resistor.

The emitters of both the BC547 are commonly connected to ground.

The base of the new BC547 gets connected to the microcontroller o/p via a suitable resistor,

may be of the order of 10K or so.

Any of the above inverting options may be selected for the desired functions.

Do not forget to connect the flyback diode across the relay coil for the above cases.

I think the first option which uses a BC557 transistor is much straight forward.

 Regards.

Sunday, 26 May 2013

Simple Audio Amp Circuit

This is an audio amplifier circuit.Here we have used femous Ic 741 as the pre amplifier.Ic 386 acts here as the Power amp.R3 resistor controls the volume.R2 contralls the gain.

Note

# This circuit operates with 9V

# Use 8ohm speaker for this

Tuesday, 14 May 2013

Long duration timer circuit

This timer circuit can be used to switch OFF a particular device after around 35 minutes. The circuit can be used to switch OFF devices like radio, TV, fan, pump etc after a preset time of 35 minutes. Such a circuit can surely save a lot of power.

Friday, 12 April 2013

Simple Audio Power Meter Circuit

This simple circuit indicates the quantity of energy that goes to a loudspeaker. The dual-color LED presentations green at an applied energy degree of about 1 watt. At 1.5 watts it glows orange and above three watts it is vivid crimson. The circuit is attached in parallel with the loudspeaker connections and that is energyed from the audio signal. The further load that this characterizes is 470 Ohm (R1//R3) will no longer be a problem for any amplifier. During the positive 1 of 2 cycle of the output sign the inexperienced LED in the dual-color LED will probably be turned on, supplied the voltage is sufficiently excessive.

At better output voltages, T1 (depending on the voltage divider R2/R1) can begin to conduct and the fairway LED will go out. During the terrible half of cycle the red LED is driven by the use of R3 and can activate when the voltage is high enough. In the transition area (where T1 habitss extra and extra and ‘throttles’ the golf inexperienced LED as a result) the combination of red/green provides the orange colour of the dual-LED. By selecting appropriate prices for the resistors the facility stages will additionally be adjusted to suit.

Circuit diagram:

$\"simple-audio-power-meter-circuit-diagram1\"$ Audio Power Meter Circuit Diagram

The worths chosen here are for conventional lounge use. You will almost definitely be stunned at how loud you have to turn your amplifier up ahead of you get the LEDs to go! The resistors can be zero.25 W sorts, supplied the amplifier does now not ship greater than forty W constantly. Above this energy the transistor may not be that happy both, so watch out for that too. Because T1 is utilized in saturation, the gain (Hfe) is on no account important and any equivalent type can be used. The power degrees talked about are valid for 4-Ohm audio system. For 8-Ohm audio system the entire resistor values have to be divided by using two.

Thursday, 11 April 2013

Simple Fluorescent Light Wiring Diagram Tube Light Circuit

The wiring process of fluorescent tube lamp/light with Ballast,Starter is quite easy and simple. In most cases when we buy a fluorescent light it comes in a complete set with all wire connected. If you want do it yourself , you can buy all the parts individually. And you can complete all connection of the fluorescent light/lamp with the help of this wiring circuit diagram.

Main parts of Fluorescent Tube Light:

1.Fluorescent Tube

2.Ballast

3.Starter

4.Holder, wire etc.

How Fluorescent Lights works:

The starter is like a key of fluorescent light because it is used to light up the tube. When we connect the AC supply voltage to the circuit, then the starter act like short circuited and current flow through those filament (located at the first and second end of the tube light) and the filament generate heat and it ionized the gas (mercury vapor) in the fluorescent tube lamp. So the gas becomes electrically conductive medium. At the same time when the starter opened the circuit path of two filaments from series connected, then the ballast release its stored voltage. And it makes the fluorescent tube fully lighten. Now the starter has no job in the circuit, if you open it from the circuit the fluorescent tube light will be still lighten, until you release the main supply.

Wednesday, 10 April 2013

Non Contact Power Monitor circuit

Here is a simple non-contact AC power monitor for home appliances and laboratory equipment that should remain continuously switched-on. A fuse failure or power breakdown in the equipment going unnoticed may cause irreparable loss. The monitor sounds an alarm on detecting power failure to the equipment. The circuit is built around CMOS IC CD4011 utilising only a few components. NAND gates N1 and N2 of the IC are wired as an oscillator that drives a piezobuzzer directly. Resistors R2 and R3 and capacitor C2 are the oscillator components. The amplifier comprising transistors T1 and T2 disables the oscillator when mains power is available. In the standby mode, the base of T1 picks up 50Hz mains hum during the positive half cycles of AC and T1 conducts.

Circuit diagram:

Non-Contact Power Monitor circuit diagram

Non-Contact Power Monitor circuit diagram

This provides base current to T2 and it also conducts, pulling the collector to ground potential. As the collectors of T1 and T2 are connected to pin 2 of NAND gate N1 of the oscillator, the oscillator gets disabled when the transistors conduct. Capacitor C1 prevents rise of the collector voltage of T2 again during the negative half cycles. When the power fails, the electrical field around the equipment’s wiring ceases and T1 and T2 turn off. Capacitor C1 starts charging via R1 and preset VR and when it gets sufficiently charged, the oscillator is enabled and the piezobuzzer produces a shrill tone. Resistor R1 protects T2 from short circuit if VR is adjusted to zero resistance.

The circuit can be easily assembled on a perforated/breadboard. Use a small plastic case to enclose the circuit and a telescopic antenna as aerial. A 9V battery can be used to power the circuit. Since the circuit draws only a few microamperes current in the standby mode, the battery will last several months. After assembling the circuit, take the aerial near the mains cable and adjust VR until the alarm stops to indicate the standby mode. The circuit can be placed on the equipment to be monitored close to the mains cable.

Source by : Streampowers

Tuesday, 9 April 2013

Remote controlled switch circuit

Here is a versatile remote controlled switch that can ON or OFF any appliance connected to it using a TV remote.

IR
remote sensor IC TSOP 1738 is used for receiving the signal. Normally
when no signal is falling on IC3 the output of it will be high. This
makes Q1 OFF.When a signal of 38 KHz from the TV remote falls on the
IC3 its output goes low.This makes Q1 conduct and a negative pulse is
obtained at pin 2 of IC 1 NE 555. Due to this IC1 wired as a monostable
multivibrator produces a 4 Sec long high signal at its out put.This
high out put is the clock for IC 2 which is wired as a Flipflop and of ,
its two outputs pin 3
goes low and pin 2 goes high. The high output
at pin 2 is amplified to drive the relay. For the next signal the
outputs of IC2 toggles state. Result, we get a relay toggling on each
press on the remote. Any appliance connected to this circuit can be
switched ON or OFF.

Remote Controlled Switch Circuit Diagram with Parts List .

Remote Control Switch Circuit

Remote Controlled Switch Circuit Diagram

Notes:

*
Before wiring the circuit make sure that the carrier frequency of the
TV remote you have is 38 kHz.For that wire the sensor part only ,point
your remote to the TSOP1738 and press any switch.If out put of TSOP1738
goes low then OK, your remote is of 38Khz type.Nothing to worry almost
all TV remote are of this type.

*
You can use any switch of the remote because for any switch the code
only changes, the carrier frequency remains same.We need this carrier
frequency only.

* Assemble the circuit on a good quality PCB or common board.

* The appliance can be connected through NO or NC and C contacts of the relay .
* Use a regulated 6V power supply for the circuit.

Monday, 8 April 2013

Sound to Dancing Lights Converter Circuit

This is a design circuit for converting an audio signal (such as one that comes from the speaker terminals of a CD player). The circuit basically consists of a buffer/amplifier stage and three filter circuits: a high-pass filter, a mid-pass filter, and a low-pass filter. The output of each filter circuit drives a light-emitting diode of different color. This is the figure of the circuit;

The input signal is fed to the buffer stage through C1. The values of RF and RV1 should be chosen so that the buffer is able to drive the three filters attached to its output. The low-frequency, mid-frequency, and high-frequency components of the input signal are only allowed to pass through the low-pass filter (bottom filter), the mid-pass filter (middle filter), and the high-pass filter (topmost filter), respectively, thus separating them from each other. Changes in the output of a filter cause its corresponding output LED to turn on and off. In effect, feeding a continuous audio signal to the input of this circuit causes the LEDs to dance.

Thursday, 4 April 2013

Microcontroller to RS 485 circuit

Microcontroller to RS-485 circuit | RS-485 bus can carry up to 256 transceiver modules and over long distances . This is a circuit for connect microcontroller with Rs-485 bus.

Max485

Max485 are low-power transceivers for RS-485 and RS-422 communication. Each part contains one driver and one receiver. Line Length vs. Data Rate The RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000 feet, see Typical Applications The MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 transceivers are designed for bidirectional data communications on multipoint bus transmission lines.

Microcontroller to RS-485 circuit

Microcontroller to RS-485 circuit diagrams

Features

- In μMAX Package: Smallest 8-Pin SO

- Slew-Rate Limited for Error-Free Data Transmission

- 0.1μA Low-Current Shutdown Mode

- Low Quiescent Current

- -7V to +12V Common-Mode Input Voltage Range

- Three-State Outputs

- 30ns Propagation Delays, 5ns Skew

- Full-Duplex and Half-Duplex Versions Available

- Operate from a Single 5V Supply

- Allows up to 128 Transceivers on the Bus

- Current- Limiting and Thermal Shutdown for Driver Overload

5 to 30 Minute Timer Circuit

A switched timer for intervals of 5 to 30 minutes incremented in 5 minute steps.

Simple to build, simple to make, nothing too complicated here. However you must use the CMOS type 555 timer designated the 7555, a normal 555 timer will not work here due to the resistor values. Also a low leakage type capacitor must be used for C1, and I would strongly suggest a Tantalum Bead type. Switch 3 adds an extra resistor in series to the timing chain with each rotation, the timing period us defined as

Timing = 1.1 C₁ x R₁

Note that R₁ has a value of 8.2M with S3 at position "a" and 49.2M at position "f". This equates to just short of 300 seconds for each position of S3. C₁ and R₁ through R₆ may be changed for different timing periods. The output current from Pin 3 of the timer, is amplified by Q1 and used to drive a relay.

Parts List
Relay 9 volt coil with c/o contact (1)
S1: On/Off (1)
S2: Start (1)
S3: Range (1)
IC1: 7555 (1)
B1: 9V (1)
C1: 33uF CAP (1)
Q1: BC109C NPN (1)
D1: 1N4004 DIODE (1)
C2: 100n CAP (1)
R6,R5,R4,R3,R2,R1: 8.2M RESISTOR (6)
R8: 100k RESISTOR (1)

R7: 4.7k RESISTOR (1)

Wednesday, 3 April 2013

A Low Cost Hearing Aid Circuit

Small and portable unit, Useful for old men and old women

This low-cost, general-purpose electronic hearing aid works off 3V DC (2x1.5V battery). The circuit can be easily assembled on a veroboard. For easy assembling and maintenance, use an 8-pin DIP IC socket for TDA2822M.

Circuit Diagrams:

A Low Cost hearing Aid Circuit

Parts:

P1 = 10K
R1 = 2.2K
R2 = 330K
R3 = 680R
R4 = 33R
R5 = 100R
R6 = 4.7R
R7 = 4.7R
R8 = 220R
C1 = 0.01uF-10V
C2 = 100nF-63V
C3 = 47uF-10V
C4 = 10uF-10V
C5 = 0.01uF-10V
C6 = 100uF-10V
C7 = 100nF-63V
C8 = 100nF-63V
D1 = Red LED
Q1 = BC547
IC1 = TDA2822M
EP1 = Mono Earphone 32R
SW1 = On-Off Switch

Circuit Operation:

In this circuit, transistor Q1 and associated components form the audio signal preamplifier for the acoustic signals picked up by the condenser microphone and converted into corresponding electrical signals. Resistor R5 and capacitor C3 decouple the power supply of the preamplifier stage. Resistor R1 biases the internal circuit of the low-voltage condenser microphone for proper working. The audio output from the preamplifier stage is fed to the input of the medium-power amplifier circuit via capacitor C2 and volume control P1.

The medium-power amplifier section is wired around popular audio amplifier IC TDA2822M (not TDA2822). This IC, specially designed for portable low-power applications, is readily available in 8-pin mini DIP package. Here the IC is wired in bridge configuration to drive the 32-ohm general-purpose monophonic earphone. Red LED (D1) indicates the power status. Resistor R8 limits the operating current of D1. The audio output of this circuit is 10 to 15mW and the quiescent current drain is below 1 mA.

Source : www.electronsforu.com

RING BELL ELECTRONIC CIRCUIT USING NE555 DIAGRAM

RING BELL ELECTRONIC CIRCUIT USING NE555 DIAGRAM

This circuit produces oscillating frequency around 1kHz, and able to be converted by changing the value of resistor R1. The speaker will produce a long beep sound with 1kHz frequency. Here is the schematic :

Parts list :

Resistor R1 : 10k ohm
Resistor R2 : 56k ohm
Capacitor C1-C2 : 0.01 uF
Polar capacitor C3 : 1 uF/15V
IC timer : NE 555
Speaker : 8 ohm 0.5 W
ON/OFF switch
5-15V Power supply

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