Posted by World Finance
on Friday, October 23, 2009
·
Here is a simple and easy to build general purpose 120 W. Amplifer with IC number TDA7293 for process sound system.
This amplifer was have the input for a radio, TV, stereo or other line level device.
It also has a phono input for a record player, guitar, microphone or other un-amplified source.
With the addition of a low pass filter at the input, it makes a great amp for a small subwoofer.
Parts
R : 660 Ohm 1/4 W Resistor = 2 pcs.
R : 22K 1/4 W Resistor = 5 pcs.
R : 10K 1/4 W Resistor = 1 pcs.
R : 30K 1/4 W Resistor = 1 pcs.
C : 2200uF 35V Electrolytic Capacitor = 2 pcs.
C : 0.22uF Capacitor = 2 pcs.
C : 22uF Capacitor = 4 pcs.
C : 0.45uF Capacitor = 2 pcs.
U1,2 : TDA7294 100W DMOS AUDIO AMPLIFIER WITH MUTE/ST-BY
T1 : 50V Center Tapped 5 Amp Transformer
S1 : SPST 3 Amp Switch
S2 : DPDT Switch
F1 : 2 Amp Fuse
SPKR1 : 8 Ohm 120W Speaker
MISC : Case, Knobs, Line Cord, Binding Posts Or Phono Plugs (For Input And Output), Heatsinks For Q1 And Q2
Posted by World Finance
·
60-100 Watt Audio Amplifier
My cause of construction of this project was to develop a compact design for a stereo amplifier can be integrated by a wrong (but the sound quality conscious!) Living student at a university or a college dormitory.
The amplifier feeds a pair of speakers with two LM3876 amplifier integrated circuits (50 watts per channel), or a pair of headphones Meier Crossfeed through a filter and a dual OPA2134 Opamp. There are four selectable line inputs, and output buffers with line level for the registry. The design with readily available components of good quality, and is divided into four BPC, a power amplifier for each channel, for the nutrition board, and for the pre-amp / headphone driver.
Above the diagram of part of the preamp board .
The output selector is sent to pins J1 and J3. Looking at the left channel, C1 and R2 form a low pass filter with a-3dB point of 40 kHz, which rejects any RF interference picked up on the interconnections. R2 also includes the impedance of the device, in this case, 47k ohms. R1 ensures Opamp U1 is presented with an impedance equal to its two inputs, contribute to improving the performance of the distortions described in the datasheet OPA2134.
The value of R1 (9K1) is universally accessible, close to the value of the parallel combination of R3 and R4 (22k and 15k, respectively). R3 and R4 set the gain at that time, just below 2.5 in this case. This gives ample space for a wide range of signal sources, which could be as much as 3VRMS. In this case, the peak output voltage of 10.6V would be fine with the project to supply ± 15V. This initial gain brings the signal to a level that the output of the volume can lead the power amp circuits directly without any additional benefit, and allows the helmet of the driver circuit to operate with a low gain, gives lower noise level. C7 forms 100kHz a lowpass filter with R3, to fall on the gain of unity at very high frequency, and to help promote stability in the Opamp. It is not strictly necessary for the proposed OPA2134 allows the unit, but down substitute cheaper but more likely oscillation device, such as the NE5532, if budgets are tight. C19 couple the AC output of this phase for volume control, and with a 50k potentiometer, the-3dB point of the response of the headphone amps at 1.4Hz (power amp has more HIGH PASS FILTER). The capacitor is very important because all the other stages are DC coupled and DC C19 prevents any of the source components, amplification and presentation of headphones or speakers.
Resistance R9 binds the production of inputs to a recording device like a VCR or mini-disc. This helps to prevent the source being loaded in the diet of both the gain stage input and the recording device and protects the source, the output should be shorted to earth for a reason whatsoever. The output from J5 and J6 are introduced into the volume control pot, which should be good quality. Finally, C3 to C6 and provide decoupling of the power supply rails, C5 and C6 high frequency decoupling, C3 and C4 lower decoupling.
Posted by World Finance
·
Useful to listen in faint sounds
1.5V Battery operation
Circuit diagram:
Amplified Ear
Parts:
P1_____________22K Log. Potentiometer (see Notes)
R1,R9__________10K 1/4W Resistors
R2______________1M 1/4W Resistor
R3______________4K7 1/4W Resistor
R4,R7_________100K 1/4W Resistor
R5______________3K9 1/4W Resistor
R6______________1K5 1/4W Resistor
R8_____________100R 1/4W Resistor
C1,C2_________100nF 63V Polyester or Ceramic Capacitors
C3,C6___________1µF 63V Polyester or Ceramic Capacitors
C4_____________10µF 25V Electrolytic Capacitor
C5____________470µF 25V Electrolytic Capacitor
D1___________1N4148 75V 150mA Diode
Q1,Q2,Q3,_____BC547 45V 100mA NPN Transistors
Q4____________BC337 45V 800mA NPN Transistor
MIC1__________Miniature electret microphone
SW1____________SPST Switch (Ganged with P1)
J1_____________Stereo 3mm. Jack socket
B1_____________1.5V Battery (AA or AAA cell etc.)
Device purpose:
This circuit, connected to 32 Ohm impedance mini-earphones, can detect very remote sounds. Useful for theatre, cinema and lecture goers: every word will be clearly heard. You can also listen to your television set at a very low volume, avoiding to bother relatives and neighbors. Even if you have a faultless hearing, you may discover unexpected sounds using this device: a remote bird twittering will seem very close to you.
Circuit operation:
The heart of the circuit is a constant-volume control amplifier. All the signals picked-up by the microphone are amplified at a constant level of about 1 Volt peak to peak. In this manner very low amplitude audio signals are highly amplified and high amplitude ones are limited. This operation is accomplished by Q3, modifying the bias of Q1 (hence its AC gain) by means of R2.
A noteworthy feature of this circuit is 1.5V battery operation.
Typical current drawing: 7.5mA.
Notes:
* Due to the constant-volume control, some users may consider P1 volume control unnecessary. In most cases it can be omitted, connecting C6 to C3. In this case use a SPST slider or toggle switch as SW1.
* Please note the stereo output Jack socket (J1) connections: only the two inner connections are used, leaving open the external one. In this way the two earpieces are wired in series, allowing mono operation and optimum load impedance to Q4 (64 Ohm).
* Using suitable miniature components, this circuit can be enclosed in a very small box, provided by a clip and hanged on one's clothes or slipped into a pocket.
* Gary Pechon from Canada reported that the Amplified Ear is so sensitive that he can hear a whisper 7 meters across the room.
He hooked a small relay coil to the input and was able to locate power lines in his wall. He was also able to hear the neighbor's stereo perfectly: he could pick up the signals sent to the speaker voice coil through a plaster wall.
Gary suggests that this circuit could make also a good electronic stethoscope.
Posted by World Finance
on Friday, October 16, 2009
·
Active Bass & Tremble Controller
ACTIVE BASS TONE CONTROLLER circuit diagram
It is very useful (and has Best Quality) for 1 -100watt AUDIO AMPLIFIERS
Download
Download this circuit in PDF
author: YMYA electronics - IZHAR FAREED
Posted by World Finance
·
STK0060 60W
Features of STK0060:
General output stage of power
amplifier has a difficult and complex problem about heat sink designing and its settings. Sanyo's DP intends to decrease electronic parts and rationalize a manufacturing process by designing IC of only output stage pf power amplifier.
- IMST Systems
- Output stage for AF high power amplifier.
- Dual power supply
- Darlington type pure/ quasi-complementary circuit
- These same pin assignment and pin interval lead to standardize a printed board.
- Metal substrate use IMST makes good thermal stability
- Able to design freely previous section of power amplifier. This leads tone control designing.
Equivalent Circuit.
Application Circuit Found the Data Sheet (SANYO)
Application Notes:
Maximum Ratings at Ta=25 deg C
Maximum Supply Voltage VCCmax +- 55V
Tehrmal resistance 0j-c idealstage 1.3 deg C/W
Collector current Ic 8A
Juction Temperature Tj 150 Dec C
Storage Temperature Tstg -30 to +105 Deg C
Allowable Load Shorting Time ts VCC=+-41V, RL 1 Sec
=8 Ohm, Po=60W
f=50Hz
*Use an Appointed Transformer.
Recommented Operation Conditions at Ta=25 Deg C
Recommented Supply Voltage VCC +-41 V
Load Resitance RL 8 Ohm
Operation Characterestic at Ta=25 Deg C, VCC= +-39V, RL=8, Rg=600 Ohm
VG-36.7db at the appointed test circuit.
Min Typ Max unit
Quiescent Current Icco VCC = +-48 20 40 70 mA
Output power Po THD=0.01%, 60 W
f=20 to 20K Hz
Total Harmonic Distortion THD1 Po=60W, f=20 to 20KHz, 0.005 0.01 %
Total Harmonic Distortion THD2 Po=1W, f=20 to 20KHz, 0.01 %
Power Band Width PBW Po=30W f= 50K Hz 0.05 %
Posted by World Finance
on Thursday, October 15, 2009
·
Analog Audio Delay Line"3d Sound"
It is fun to make a variable space in your small room, but it’s hard to make the actuator to move your wall or room partition. Using analog audio line delay, you can adjust your room virtually. Just turn a knob in your audio set and you can adjust your room size. The circuit described here will make your dream come true, giving a feel that your speaker is located 15 meters behind you, even though your room is actually 3 meters wide. Here is the circuit’s schematic diagram.
The core of this circuit is SAD512D integrated circuit, an analog audio delay. The chip uses 512 capacitors memory to hold 512 sampled analog signal. The delay can be adjusted from about 5,1 ms to 51 ms by R12 pot. Feed the input of this analog delay circuit with a mixed right and left audio signals from your stereo system. The output of this circuit then fed to a small power amplifier and place the output speaker behind you. Now you can perceive like your speaker is 15 m away behind (with maximum delay setting). If you build two unit the cascading the circuit will result in 30 meter expansion of your virtual room.
The circuit consist three main block. The first block (U1A, U1B) is a fourth order low pass filter (-24dB roll-off per octave) with 2.5kHz cut off frequency. The second block is the adjustable analog delay integrated circuit (IC SAD512D). The delay is controlled by the oscillator around U2 which is adjustable from 5KHz to 50Khz. The last block is similar to the first block, a low-pass filter with 2.5KHz cut off frequency.
A variable resistor R9 is provided to adjust the input offset, avoiding signal clipping and maximizing the audio range. For easy adjustment, feed the input with high level audio signal until the output is distorted, then adjust R9 until the distortion is minimum, or if an oscilloscope is available, adjust the R9 until the clipping is equal for both positive and negative cycle. Finally, adjust R28 to give minimum sampling clock noise.
PARTS LIST
Reference Part
C1,C4,C10,C12 10n
C11,C2 1n5
C3 4.7uF/50V
C13,C5 1n9
C6 390p
C8,C7 1u/25V
C9 1uF/25V
C14,C15,C16 100n
J1 input connector
J2 out connector
R1,R2,R3,R5,R6,R7,R11,R20,R21,R22,R24,R25,R26 10k
R4,R23,R27 4k7
R8,R15 15k
R9 2k2 POT
R10 2k7
R12 220k POT
R13 10R
R18,R14 1k
R17,R16 330R
R19 100k
R28 250R trimpot
U1 TL084
U2 4011
Posted by World Finance
on Monday, October 12, 2009
·
LM386 circuit audio amplifier
The LM386 circuit is a audio amplifier designed for use in low voltage consumer applications. The gain is internally set to 20 to keep external part count low, but the addition of an external resistor and capacitor between pins 1 and 8 will increase the gain to any value from 20 to 200.
The inputs are ground referenced while the output automatically biases to one-half the supply voltage. The quiescent power drain is only 24 milliwatts when operating from a 6 volt supply, making the LM386 ideal for battery operation.
LM386 circuit features
- Battery operation
- Minimum external parts
- Wide supply voltage range: 4V–12V or 5V–18V
- Low quiescent current drain: 4mA
- Voltage gains from 20 to 200
- Ground referenced input
- Self-centering output quiescent voltage
- Low distortion: 0.2% (AV = 20, VS = 6V, RL = 8Ω, PO = 125mW, f = 1kHz)
- Available in 8 pin MSOP package
LM386 circuit applications
- AM-FM radio amplifiers
- Portable tape player amplifiers
- Intercoms
- TV sound systems
- Line drivers
- Ultrasonic drivers
- Small servo drivers
- Power converters
LM 386 series output power (Pout)
- LM386N-1, LM386M-1 at VS = 6V, RL = 8ohms, THD = 10% is 250-325 mW
- LM386N-3 at VS = 9V, RL = 8ohms, THD = 10% is 500-700 mW
- LM386N-4 at VS = 16V, RL = 32ohms, THD = 10% is 700-1000 mW.
LM 386 amp circuit 20dB gain
LM386 Audio Amplifier with Gain = 20 and minimum part count.
LM386 audio amp 50dB gain
LM386 amplifier 200dB gain
LM 386 bass boost circuit
To make the LM 386 a more versatile audio amplifier, 2 pins ( pin 1 and 8 ) are provided for gain control. With pins 1 and 8 open the internal 1.35k resistor sets the gain at 20 (26 dB). If a capacitor is placed between pin 1-8, bypassing the built-in 1.35k resistor, the gain will go up to 200.
If a resistor is placed in series with the capacitor, the gain can be set to any value from 20 to 200. Gain control can also be done by capacitively coupling a resistor or FET transistor from pin 1 to the ground.
Posted by World Finance
·
Introduction To Home Stereo Amplifer
This is a 1 watt home stereo amplifier module project using the KA2209 IC from Samsung, which is equivalent to the TDA2822. It operates from 3-12V DC and will work from a battery since the quiescent current drain is low. It requires no heat sink for normal use. The input and output are both ground referenced. Maximum output will be obtained with a 12V power supply and 8 ohm speaker, however it is particularly suitable for driving headphones from a supply as low as 3V.
The Specifications of the home stereo amplifier are:
D.C. input : 3 – 12 V at 200 – 500 mA max
Idle current : approx. 10 mA
Power output : > 1 Watt max. 4-8 ohms, 12V DC
Freq. Resp. : approx. 40 Hz to 200 kHz, 8 ohm, G=10
THD : <> 80 dB, G = 20 dB
Sensitivity : < g =" 20">
Home Stereo Amplifier Description
Home Stereo Amplifier Parts List
The gain is adjustable from 10 to 100, i.e. 20 to 40 dB. Start with feedback resistors R1 and R3 of 1k ohm, this will give a gain of 10 which should be adequate for most applications. If you require more gain, you can remove resistors R1 and R3. This will give a gain of approximately 100, or 40 dB.The input attenuation can be adjusted via the potentiometer which can be used as a volume control. The IC gain should be kept as low as necessary to achieve full output, with the input potentiometer and your signal source at maximum.
This will keep the signal to noise ratio as high as possible. Extra gain provided by the amplifier will reduce the S/N ratio by a similar amount, since the input noise figure is constant. Other values for R1 and R3 of between 1k and 10k ohm can be used if an intermediate gain level is required.
Voltage Gain = 1+ R1/R2 = 1+R3/R4, however the maximum gain with no external feedback is approximately 100, or 40dB. (GdB = 20log Gv)
If driving a pair of headphones, you may also require a 100 ohm resistor in series with each output to reduce the output level, depending on headphone impedance and sensitivity. Make sure you start with the volume right down to check. A number of headphones may be driven from the one amplifier if you wish, since most headphones have at least 16 ohm impedance, or more commonly 32 ohm.
There are only a few external components, the IC contains most of the necessary circuitry. R1,R2 and R3,R4 are the feedback resistors. C1 provides power supply decoupling. C2 and C3 are the input coupling capacitors, which block any DC that might be present on the inputs. C4,C5 block DC in the feed back circuit from the inverting inputs, and C6,C7 are the output coupling capacitors. C8, R5 and C9,R6 act as zobel networks providing a high frequency load to maintain stability at frequencies where loud speaker inductive reactance may become excessive. The pot provides adjustable input level attenuation.
Posted by World Finance
on Saturday, October 10, 2009
·
Zenit PCB is a freeware layout software
ZenitPCB Layout is an excellent tool to create professional printed circuit board ( PCB ).
It is a flexible easy to use CAD program, which allow you to realize your projects in a short time.
ZenitPCB Layout is completely freeware for personal or semi-professional use
System OS Tested Windows2000 - Windows XP - Vista
ZenitSuite142_Setup.exe New
website: zenitpcb
Posted by World Finance
on Thursday, October 1, 2009
·
Digital vs. Analog Volume Control
Digital vs. Analog Volume Control
| The volume control in digital processors (or CD players) can be implemented in the analog or the digital domain. That is, the analog signal can be put through a standard volume-control knob as is found on a preamplifier, or the volume can be adjusted by performing mathematical operations on the digital data representing the music. Before deciding a digital processor with volume control, you should know the tradeoffs inherent in each approach. An analog volume control can slightly degrade the signal - no volume control is perfectly transparent - and can introduce small channel balance errors at certain volume settings. For example, when the volume is turned very low, the left channel may be half a dB louder than the right. This situation could reverse as the volume is turned up. A digital volume control has its own problems. Each 6dB reduction in volume from the maximum setting throws away one bit of resolution. A low volume setting (say, 30dB of attenuation) is equivalent to discarding five bits. If you had true 20-bit resolution in your D/A converter, you'd be listening to 15-bit audio instead of 20-bit. The lower the volume setting, the greater the loss in resolution. Digital volume control such as DS1669 from Dallas Semiconductor is actually easier and cheaper to implement than analog volume control. Most digital filters have a volume control built-in; the designer need only send a control code to the filter chip to adjust the volume. An analog control requires a potentiometer (the volume control itself), another hole in the chassis, and wiring between the circuit board and potentiometer.Source: Digital vs. Analog Volume Control |
Posted by World Finance
on Thursday, September 3, 2009
·
Dual Voltage Power Supply
author: YMYA electronics - IZHAR FAREED
Description
The following circuit Diagram of (DUAL VOLTAGE POWER SUPPLY ) can be used for Misc.. application.
It requires a few components to built. The most important components of this circuit are REGULATORS.
1 : (AN) 7812 and 2 : (AN) 7912 AN7812 is the Positive Voltage Regulator. It regulates the voltage from (almost) 24vDC to 12vDC (accurate). AN7912 is the Negative Voltage Regulator. It regulates the voltage from (almost) -24vDC to -12vDC. A transformer output must be between 12vAC to 24vAC @ 500mA. Input of transformer (Primary)
should be about 110vAc-220vAC. It also include some capacitors to filter the current.
Download
Download this circuit in PDF
Source: Dual Voltage Power Supply
Posted by World Finance
·
5 Lamp / LED Flash Driver
author: Rajkumar Sharma
Description
General Description of the following circuit. This circuit is based around HT2050 manufactured by HOLTEK semiconductors. It is a low cost, low-power C-MOS LSI designed for lamp andLED flash driver. It requires minimum external components.You can operate it with just two AAA cell or 3v Battery.Circuit has five flash outputs with 10mA drive capability that can implement random or sequence flashing function controlled by one option pin.It only requires one external resistor for typical application. It is very suitable for the use of the flash products such as disco glasses, disco hat, gift card, Xmas decoration and so forth.
Download
Download this circuit in PDF
Source:
5 Lamp / LED Flash Driver
Posted by World Finance
·
20W Bridge Audio Amplifier
author: Rajkumar Sharma
| 20W Bridge Audio Amplifier kit, based on the TDA2005 IC, a class B dual audio amplifier, specifically designed for car radio applications etc.
-
Power supply - 18 VDC -
Output power - 20 W, 4 Ω -
IC built in Thermal Shut-down, Load dump voltage surge protected -
Terminal pins for connecting left and right audio signal inputs -
Relimate Connector for connecting Potentiometer (POT) for volume adjustment -
Power Battery Terminal (PBT) for easy power supply and speaker connection -
Power-On LED indicator -
Heatsink for IC -
Four mounting holes of 3.2 mm each with nut and stud -
PCB dimensions 63 mm x 65 mm
|
Schematic
Parts List
PCB
Download
Download this circuit in PDF
Source: 20W Bridge Audio Amplifier
Posted by World Finance
·
Notch Filter
Circuit : Andy Collinson
Email me
Description:
A variable notch filter with both high and low pass filters.
Notes
At first glance this circuit looks fairly complex, but when broken down,can be divided into high pass and low pass filter sections followed by a summing amplifier with a gain of around 20 times. Supply rail voltage is +/- 9V DC. The controls may also be adjusted for use as a band stop (notch) filter or band pass filter.Source: http://www.zen22142.zen.co.uk
Posted by World Finance
·
Circuit : Andy Collinson
Email me
Description:
A stereo line driver for feeding long cables or buffering an audio source.
Notes
This preamplifier has a low output impedance, and is designed to drive long cables, allowing you to listen to a remote music source without having to buy expensive screened cables. The very low output impedance of around 16 ohms at 1KHz, makes it possible to use ordinary bell wire,loudspeaker or alarm cable for connection. The preamplifier must be placed near the remote music source, for example a CD player. The cable is then run to a remote location where you want to listen. The output of this preamp has a gain of slightly less than one, so an external amplifier must be used to drive loudspeakers.Source: http://www.zen22142.zen.co.uk
Posted by World Finance
·
Two examples of the most common types of Voltage followers (buffers). You can find some theory behind them in our amplifier gain and buffer amplifier pages.
Transistor voltage follower:
This first circuit is a very simple one transistor voltage follower. Consist of two biasing resistors, and one other resistor at the emitter to acquire the output voltage from.
How it works:
The first to resistors connected to the transistor's base are forming a voltage divider, in order to set a biasing point for the transistor to work in our desired range. Then the transistor, our gain component for the circuit which in this case is only used as a gateway to isolate two circuit stages.
The resistor in the emitter is used to create a voltage from the current passing from the transistor; Without it we can't get any voltage as our output would be effectively shorted to ground (0 volts).
The capacitors that are displayed in the schematic are optional, but very useful to prevent a wrong operation of the circuit, specially in audio or high frequency uses. they stop any DC voltage to move or otherwise disrupt the bias point of the transistor, thus causing undesired operation. If you build this circuit only with dc remove the capacitors, as they will prevent the circuit from functioning under those conditions.
Transistor voltage follower
Op Amp Voltage Follower:
This circuit's operation is far more predictable and stable than the transistor version, and also requires less external components.
How it works:
Works as described above, no external elements to explain. This circuit uses feedback to maintain the voltage output the same as the input. Note that this schematic does not display power, ground and other connections for the op amp, these vary widely among manufacturers and op amps so refer to your op amp's datasheet for pinouts and power connections.
Opamp voltage follower
Source: Electronic Circuits For Beginners
Posted by World Finance
on Tuesday, September 1, 2009
·
5 Zone Alarm System
Circuit : Andy Collinson
Email: anc@mitedu.freeserve.co.uk DescriptionThis is a complete alarm system with 5 independent zones suitable for a small office or home environment. It uses just 3 CMOS IC's and features a timed entry / exit zone, 4 immediate zones and a panic button. There are indicators for each zone a "system armed" indicator. The schematic is as follows:
Circuit Notes:Each zone uses a normally closed contact. These can be micro switches or standard alarm contacts (usually reed switches). Suitable switches can be bought from alarm shops and concealed in door frames, or window ledges.Zone 1 is a timed zone which must be used as the entry and exit point of the building. Zones 2 - 5 are immediate zones, which will trigger the alarm with no delay. Some RF immunity is provided for long wiring runs by the input capacitors, C1-C5. C7 and R14 also form a transient suppresser. The key switch acts as the Set/Unset and Reset switch. For good security this should be the metal type with a key.Operation: At switch on, C6 will charge via R11, this acts as the exit delay and is set to around 30 seconds. This can be altered by varying either C6 or R11. Once the timing period has elapsed, LED6 will light, meaning the system is armed. LED6 may be mounted externally (at the bell box for example) and provides visual indication that the system has set. Once set any contact that opens will trigger the alarm, including Zone 1. To prevent triggering the alarm on entry to the building, the concealed re-entry switch must be operated. This will discharge C6 and start the entry timer. The re-entry switch could be a concealed reed switch, located anywhere in a door frame, but invisible to the eye. The panic switch, when pressed, will trigger the alarm when set. Relay contacts RLA1 provide the latch, RLA2 operate the siren or buzzer.Source:www.zen22142.zen.co.uk
Posted by World Finance
·
Emergency Light & Alarm
Powered by two AA NI-CD batteries
Four switchable options
Parts:
R1____________220K 1/4W Resistor
R2____________470R 1/2W Resistor
R3____________390R 1/4W Resistor
R4______________1K5 1/4W Resistor
R5______________1R 1/4W Resistor
R6_____________10K 1/4W Resistor
R7____________330K 1/4W Resistor
R8____________470R 1/4W Resistor
R9____________100R 1/4W Resistor
C1____________330nF 400V Polyester Capacitor
C2_____________10µF 63V Electrolytic Capacitor
C3____________100nF 63V Polyester Capacitor
C4_____________10nF 63V Polyester Capacitor
D1-D5________1N4007 1000V 1A Diodes
D6______________LED Green (any shape)
D7___________1N4148 75V 150mA Diode
Q1,Q3,Q4______BC547 45V 100mA NPN Transistors
Q2,Q5_________BC327 45V 800mA PNP Transistors
SW1,SW2________SPST Switches
SW3____________SPDT Switch
LP1____________2.2V or 2.5V 250-300mA Torch Lamp
SPKR___________8 Ohm Loudspeaker
B1_____________2.5V Battery (two AA NI-CD rechargeable cells wired in series)
PL1____________Male Mains plug
Device purpose:
This circuit is permanently plugged into a mains socket and NI-CD batteries are trickle-charged. When a power outage occurs, the lamp automatically illuminates. Instead of illuminating a lamp, an alarm sounder can be chosen.
When power supply is restored, the lamp or the alarm is switched-off. A switch provides a "latch-up" function, in order to extend lamp or alarm operation even when power is restored.
Circuit operation:
Mains voltage is reduced to about 12V DC at C2's terminals, by means of the reactance of C1 and the diode bridge (D1-D4). Thus avoids the use of a mains transformer.
Trickle-charging current for the battery B1 is provided by the series resistor R3, D5 and the green LED D6 that also monitors the presence of mains supply and correct battery charging.
Q2 & Q3 form a self-latching pair that start operating when a power outage occurs. In this case, Q1 biasing becomes positive, so this transistor turns on the self latching pair.
If SW3 is set as shown in the circuit diagram, the lamp illuminates via SW2, which is normally closed; if set the other way, a square wave audio frequency generator formed by Q4, Q5 and related components is activated, driving the loudspeaker.
If SW1 is left open, when mains supply is restored the lamp or the alarm continue to operate. They can be disabled by opening the main on-off switch SW2.
If SW1 is closed, restoration of the mains supply terminates lamp or alarm operation, by applying a positive bias to the Base of Q2.
Notes:
-
Close SW2 after the circuit is plugged.
-
Warning! The circuit is connected to 220Vac mains, then some parts in the circuit board are subjected to lethal potential!. Avoid touching the circuit when plugged and enclose it in a plastic box.
This circuit was awarded with publication in ELECTRONICS WORLD "Circuit Ideas", September 2001 issue, page 708.
Source : http://english.cxem.net/guard/guard17.php
Posted by World Finance
on Sunday, August 30, 2009
·
This simple counter can be used to count pulses, as the basis for a customer counter (like you see at the doors of some stores), or for anything else that may be counted. The circuit accepts any TTL compatible logic signal, and can be expanded easily (see Notes).
Schematic
7 Segment Display Reference
Parts
| Part | Total Qty. | Description | Substitutions |
| R1-R7 | 7 | 470 Ohm 1/4 Watt Resistor |
|
| U1 | 1 | 74LS90 TTL BCD Counter IC | 7490,74HC90 |
| U2 | 1 | 74LS47 TTL Seven Segment Display Driver IC | 7447,74HC47 |
| DISP1 | 1 | Common Anode 7 Segment LED Display |
|
| MISC | 1 | Board, Sockets For ICs, Wire |
Notes
- All pulses to be counted are to be TTL compatible. They should not exeed 5V and not fall below ground.
- You can add more digits by building a second (or third, or fourth, etc...) circuit and connecting the pin 11-6 junction of the 74LS90 and 74LS47 to pin 14 of the 74LS90 in the other circuit. You can keep expanding this way to as many digits as you want.
Source : http://www.aaroncake.net/circuits/counter.asp
Posts
