Top Circuits Page 57
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The Tab antenna is a folded monopole that you miniaturize by forming it into an inverted L with a downward bend at the end (Figure 1). You can solder it perpendicular to a pc board or build it as part of a pc board and place it at a corner. The folded....
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Here's something that has always bugged me: light waves are about 5000 Angstroms in wavelength, while atoms are more like 1 Angstrom across. Atoms are thousands of times smaller than light waves, yet atoms obviously interact very strongly with light. How can....
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Got no dough for a commercial WiFi antenna? Looking for an inexpensive way to increase the range of your wireless network? A tin can waveguide antenna, or Cantenna, may be just the ticket. This design can be built for under $5 U.S. and reuses a food, juice,....
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City dwellers and other flat dwellers know the practical difficulties they encounter when they try to put up an antenna for 40 meters. Finding space enough to accommodate 67 feet of wire is a real problem for them and most of them have to be satisfied by the....
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This Antenna is most widely used all over the world. For example, when you see a police car it has a transmitter with Ground Pole Antenna The body of car serves as ground). It accepts load from 50 ohm source and has larger power output than Half-Wave Dipole....
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Antenna is the means by which a wireless operator puts his signal into the space and also through which he picks up the signals of the stations with which he wants to communicate. Hence after having a good Receiver and a Transmitter (or Transceiver), the....
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This antenna is made from 1/2" copper tubing and it is soldered together with plumbing tees, elbows, and nipples....
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At VHF, both the 1/4-wavelength monopole and the 5/8-wavelength monopole antennas are widely used. The VHF 5/8-wavelength (144 Mhz) vertical monopole has long held the reputation of providing about a 3-dB gain advantage over the 1/4-wavelength vertical....
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SWR can be adjusted by adjusting the connection point L3 figher or lower...
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Use for this antenna tube of 10mm diameter. Or you can use a brass rod of about 7mm diameter. The top one is a strong copper (brass) wire of 5 to 7 mm diameter soldered directly to the coil and mounted to the PVC isolator to give a strong construction...
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To calculate the length of the elements of other bands use the above formula. Example 6 meter band (50Mhz): (75/50)*0.96=1.44 meters..
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This is a Full wave omni directional vertical ground plane antenna for 2-meters plan with 250 watts max power...
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You can make your own 2-meter "rubber duckies" that will likely perform much better than many commercial units. I compared my design with two other "rubber duckies" of the TH215 and ICT7 which outperformed them both. With the "duckie" of the ICT7e as much as....
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This design notes shows a UHF 3-element portable antenna with gamma-match...
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I wanted a robust, portable, compact antenna usable for horizontal and vertical polarisation to take along with my FT-817 when I go on vacation, camping etc. I also wanted the dipole to cover the VHF and UHF bands and if possible with some gain! As everybody....
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Most of us don`t have the luxury of building a 1/4, 1/2 or even a 5/8 wavelength vertical antenna for HF. We have to settle for something a little shorter. (A lot shorter, in the case of people following the FCC`s Part 15 rules, which limit them to 3 meters....
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This circuit is designed to be used in conjunction with the standard 4 foot square loop used in MW for long distance reception...
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The load described here is capable of handling up to 10 watts of RF power for a couple of minutes, and is designed for the widely used 50 ohms impedance. It consists of ten parallel connected 560 ohms 1 watt resistors, R1 through R10, a voltage divider,....
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Described here is a simple omnidirectional, vertically-polarised dipole for two metres. Made from coaxial cable, it can be rolled up and stored in a small container. It may be used as is indoors, or waterproofed for use outside. No extravagant gain claims....
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The circuit of Figure 1 provides the termination voltage for both 1.8 and 2.5V memory systems and delivers output current as high as 6A. IC1 includes a step-down controller and two linear-regulator controllers and operates with input voltages of 4.5 to 28V...
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The circuit in Figure 1 is an FPGA-based, synchronous FIFO that uses the same clock for read and write operations. The circuit can generate FIFO-occupancy flags with a minimum of logic. The boxed area in Figure 1 shows a more conventional occupancy meter.....
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You use the fully controlled circuit in Figure 1 to parallel-program two-wire serial EEPROMs via the I2C bus. Gang programmers must address all memory devices during a write operation. To verify the memory contents, however, the system must address only one....
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This programmer was designed in view of to be flexible, economical and easy to built, the programmer hardware utilizes the standard TTL series parts and no special components are used. The programmer is interfaced with the PC parallel port and there is no....
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Some RISC controllers, like the NEC V850 family, use an internal 32-bit architecture with an external 16-bit bus. The architecture also allows interfaces with 8-bit memories. However, with 8-bit memories, accesses to and from odd locations automatically....
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The VPP generator circuits shown here cover a range of
30mA to 240mA with 3.3V or 5V inputs as noted. Table 1
summarizes these circuits for quick reference...
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The four 1K resistors on the output of U6 are too high in value for some parallel ports. Change these to 100ohm. Some LSI based parallel ports use active pull-up resistors and these are lower than the nominal 4K7 which causes a voltage divider effect. A bad....
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Digital signal processing circuit when work needs to cooperate with it with a memory for temporarily storing image data. DPTVT-3D/MV digital processing chip need four KM416S102..
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Discharge After the memory circuit After the memory circuit is also an instantaneous action, the delay reset circuit. When the input signal to a movement that is open when the ..
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Discharge before memory circuit Before the memory circuit is considered instantaneous action, the delay reset circuit. When the input signal to one that is action, and start ti..
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Structure and working principle of this circuit is basically the same as the previous circuit, but with some of the components used in the functional minor Ran o First show different bands of the circuit is divided into seven bands, the center frequency of....
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Newman MP4 machine has three atj memory, a data memory is used to store data U7 # - one is used to store the MP4 machine work program program memory U} 8 = The last parameter is used to store user settings user memory U9. Data memory circuit arrangement in....
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The circuit in Figure 1 eliminates the need for adjustments. The circuit uses dc-coupled feedback to control the current in the output resistor. Hence, the output voltage is predictable and constant...
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This circuit will activate a relay when light falls to a preset level. Light level can be adjusted with VR1 and the relay contacts may be used to operate an external light or buzzer...
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This device allows one or more lamps to illuminate at sunset and turn off at dawn.
Q1 and Q2 form a trigger device for the SCR, providing short pulses at 100Hz frequency. Pulse duration is set by R2 and C1...
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This circuit adopts the rather unusual Bowes/White emitter coupled multivibrator circuit. The oscillation frequency is about 1Hz and is set by C1 value. The LED starts flashing when the photo resistor is scarcely illuminated. The onset of flashing can be set....
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The following is a method to allow day and night detection using Infrared/Visible light sensitive phototransistors and a simple LM339 voltage comparator circuit...
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Variable resistor R1 adjusts the light threshold at which the circuit triggers. R1`s value is chosen to match the photocells resistance at darkness. The circuit uses a CMOS 4001 IC. Gate U1a acts as the trigger, U1b and c form a latch. S1 resets the circuit.....
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This train detector makes use of hand held laser pointer devices that are widely available to detect trains over long distances...
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This page presents information on infrared - `Across The Track` train detection circuits. The circuits are designed around the LM339 comparator chip and can use a wide assortment of matched infrared - emitter / detector pairs...
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This page features basic, visible light photo-detector circuits that can be used to detect trains. These methods would normally be used with the photo sensor mounted between the rails...
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DC power supply can also be controlled via an optical fiber. The circuit is a small DC motor ( 1/12hp) providing an insulating speed control channel. The control logic is an in..
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The output of the amplifier is to be measured on a digital voltmeter. Besides being able to accept 20 na to 200 micro amps and output voltages that range form 100 mv to 2 or 3 volts, the amplifier needed to have a low input resistance so the diode could be....
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When the phototransistor is stroken by IR light it conducts and the voltage between the 1Mohm resistor(arbitrary) and the phototrans drops from VCC to lower values. When the voltage drops lower than VCC/3 the 555 is triggered and goes high (from 0 TO VCC).....
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Fans (Ceiling) Fifth gear speed control circuit shown in Figure 3-6. It uses capacitor step-down, three-terminal fixed 7806 integrated steady voltage regulator Ai regulator to ..
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FIG sensitive ((InW) .OPA111 optical receiver amplifier feedback resistor of FIG 200Mn, because the gain of the amplifier is high .OPAI11 receiving signals transmitted over an ..
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Ethernet is the most widely used networking technology with high reliability, media informative, easy to expand and update, etc., in businesses, schools and other fields are wi..
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Dimming control circuit as shown in FIG. Single-chip I/O port sinking method to achieve control thyristor switch and dimming control. MOC3041 optocoupler with internal zero-cro..
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Semiconductor color sensor having an identification of the object color capacity by three photodiodes PD1, PD2, PD3 and three color filters X-PHOTO, Y-PHOTO and Z-PHOTO constitution. Respectively mounted on each of the photo diode red (R), green (G), blue ..
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A reflex isolators (A) the light reflected by an object detecting its presence. When an object is very close to the sensor (B), this technique can be used to detect circuit. ..
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A, RS485 bus Introduction RS485 bus is a common serial bus standard, using balanced differential transmit and receive mode, and therefore has the ability to suppress common mod..
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As shown by the bistable circuit and optocoupler transistor of FIG. In the initial state the moment the supply voltage is turned on, the transistor VT off, the circuit outputs ..
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As shown is a very attractive Christmas lights circuit. When the power is turned on, lights HL will gradually become brighter; when it reaches the brightest, it will automatica..
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By the photocell photoelectric tracking circuit configuration, with two similar performance as a photoelectric cell the same light receiving device. When the incident light flu..
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Circuit is shown. Group 4 analog electronic circuit switch (S1 ~ S4): S1, S2, S3 for parallel delay circuit, when the power is turned on by their R4, VB6 drive Triac VT, VT dir..
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The easy way to clamp a signal to a given value is to use two zener diodes, connected back-to-back. This method has several disadvantages. The accuracy of the clamping depends on the tolerance of the zener diodes, and the clamping is not adjustable, except....
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Resonant power supplies are popular because of high efficiency, low noise, and compactness. You can implement a resonant buck or boost converter using a single switch. The regulation of the output in such a converter derives from using a constant on or off....
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The schematic for a monostable multivibrator is shown in figure 3-11. Like the astable multivibrator, one transistor conducts and the other cuts off when the circuit is energized...
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Figure 1 shows how to digitally program the on-time of a one-shot multivibrator circuit. More and more, the Internet is playing a role in control operations in industrial and R&D endeavors and in household appliances. One-shot circuits are popular....
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You use a frequency discriminator to compare one signal frequency with another one. A functional feature, retriggering, of a monostable, one-shot 74xx123 multivibrator can yield frequency discrimination. Figure 1 shows a frequency discriminator that....
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Here the popular 555 timing IC, is wired as a monostable. The timing period is precise and equivalent to:-
1.1 x R1 x C1
With component values shown this works out at approximately 1.1msec.The output duration is independant of the input trigger....
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The two circuits below illustrate using the 555 timer to close a relay for a predetermined amount of time by pressing a momentary N/O push button. The circuit on the left can be used for long time periods where the push button can be pressed and released....
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The logic diagram of the CD4538BC Dual Precision Monostable is shown in the following schematic diagram. This IC such a dual, precision monostable multivibrator with independent trigger and controls, according to the datasheet. This CD4538BC IC features wide....
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Introduction to circuit schematic of the circuit shown in Figure 3-3. Here the 555 connected as a one-shot form, usually in a normally open push button switch..
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This circuit is simple. The first 555 timer prevents the second timer from being triggered while the first is running...
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Exars XR-L555 circuit typical power consumption is 900 W, the power supply voltage of 5V, micro-power circuit, XR-L555 can be used directly in place of the 555 timer. Delay by ..
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Dual Timer Exar XR-2556 for the first time after the timing of the output can be triggered by capacitive coupling second timing pin. When the trigger input is used, in order to..
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555 Timer enables low-loss single-shot circuit and CMOS4011B NAND gate circuit interface. Standby power consumption of less than 50 A. When the one-shot circuit is turned on, t..
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A CMOS NAND gate or NOR gate can form a single-shot, this single-shot circuit extensively used to delay the pulse signal, stretching and shaping. Monostable door circuit, its m..
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A video amplifier output at its arrival was a differentiation before the Schottky comparator. Typical propagation delay is reduced to 10ns. The output pulse width is set by the..
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As shown by 555 and the timing resistor R1 ~ R3 and measured capacitance Cx can be composed pointer capacitance meter, one-shot circuit capacitance measurement principle is the..
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As shown in the timer 555 is triggered by the positive trigger pulse, then a negative output pulses. In the absence of beating duty cycle greater than 99%. Heavy loads can be s..
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As shown, the circuit including a four 2-input NAND gate and a CMOS CD4011 type 555, and thus the output of either a static or high-time period, the power consumption is minima..
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Child lock voltage comparator 555 monostable circuit, a counter, JK flip-flop, UPS power supply design digital logic circuit, electronic door control, and a variety of addition..
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Circuit diagram all three parts of the series resonant crystal and triple CD4049 inverter connection. Supply voltage range is 3-15V. Compact, low-power RF oscillator portable b..
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Combined monostable multivibrator 555 and a pair of light control and light control comparator monostable phase. Depending on the time of the circuit can be used to enable load..
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Common monostable circuit in two ways: manual start type and start pulse type. Single-shot pulse start ..
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This is a prototype of the WA4DSY 56KB RF modem. It is intended for use on amateur packet radio networks. The modem generates RF in the 28 to 30 mhz range and requires and linear transverter to convert the signal to a UHF or microwave ham band. The digital....
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The LT1886 is a high speed dual power amplifier with
excellent high frequency distortion performance. The
LT1886 features a 700MHz gain-bandwidth product,
200V/ms slew rate and over 200mA of output current
drive in a small SO-8 package. Using only a....
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No description available...
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The 2400-bps modem in Figure 1 makes it easy to connect a Basic Stamp (Parallax Inc, www.parallaxinc.com) to a telephone modem. Using this circuit, you can call home via your PC and find out if the house is still there. The Basic Stamp2, BS2-IC, has the....
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1. Because there is no DTR wire (modem pin 20) from Pilot. Pilot can simulate DTR line but this is not used at this moment (needs a pull-up)
2. This way we can not dial without a known dial tone if needed (like in some areas out of USA)
3. There no....
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The popularity and easy access of RS-232 ports lend them to many communication projects. You can use a port as is” or as a tiny parallel port when the exchange uses only control lines. Before the asynchronous serial-data transfer between two devices can take....
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First of all you have to build one cable adapter to connect the female 9pins connector of the modem, with female 9pins connector of the base of E-10G HPC. To build the null modem cable you will need: 2 male connectors with 9 pins. 15cm cable with 7 wires.....
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For wiring to the microphones I used a wiring harness from an old portable headphone set. Find one with a 90 degree miniplug if possible. Cut off the headphones, solder the condensor mics to the leads and voila. Anything larger than the pencil soldering....
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Here is one that uses a single IC (LM324 quad op amp)
and a handful of parts. This circuit is for detecting one of those 3.6khz..
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The 2 pushbuttons = S1: Start/Pause. S2: Stop/Reset. If you want to play your message, put S3 at Play. Then push S1 to start playing and again to pause. If you want to delete your message press S2 twice. If you want to record a message put S3 at Rec. Then....
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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....
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One of my prize pieces of equipment is a pair of Sony C-37A large capsule tube, condenser microphones. I bought these from the radio station at college because they were getting hard to use, and an intermittent connector problem resulted in a nasty....
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This circuit is mainly intended to provide common home stereo amplifiers with a microphone input.
This circuit is mainly intended to provide common home stereo amplifiers with a microphone input.
Using a stereo microphone the circuit must be doubled. In....
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This is a very simple design for a phantom supply. This design will work with microphones that have no problem with the phantom supply being only 15V. It also has to be noted that, at high SPL, distortion can become intolerable (totally depending on....
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The circuit is a microphone amplifier for use with low impedance (~200 ohm) microphones. It will work with stabilized voltages between 9-30VDC. If you don`t build the impedance adapter part with T1, you get a micamp for higher impedance microphones. In this....
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FM Wireless Mike can transmit voice signals to any FM Radio receiver 100 meters away. The circuit is basically a frequency modulated transmitter working at 100 MHz. The frequency of the transmitter can be varied slightly by changing the trimmer C5. You can....
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This relatively simple mixer was designed for three dynamic microphones, but can be re-designed for more or less. Level and tone controls are available to tailor the sound to your needs...
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This is a simple microphone preamplifier circuit which you can use between your dynamic microphone and any equipment designed to work with an electret microhone (2 wire connection to electret capsule). This amplifier amplifies the low level signal to the....
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The circuit is a microphone amplifier for use with low impedance (~200 ohm) microphones. It will work with stabilized voltages between 6-30VDC. If you don`t build the impedance adapter part with T1, you get a micamp for higher impedance microphones. In this....
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In its simplest form, a voice-over unit is just a microphone and change-over switch feeding an amplifier, the output from the microphone having priority over the amplifiers audio signal when the "push-to-talk" switch is pressed. In this circuit, a....
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This circuit uses a TBA820 audio 1C to amplify underwater sounds. The microphone must be waterproofed. This project was originally used in a home aquarium to monitor fish sounds...
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The 24 watt amp is easy to build, and very inexpensive. The circuit can be used as a booster in a car audio system, an amp for satellite speakers in a surround sound or home theater system, or as an amp for computer speakers. The circuit is quite compact and....
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What got me interested in building these diminutive devices is the S3FM connector assembly made by Switchcraft. The S3FM is simply a 3.5-inch tube fitted with a male XLR at one end and a female at the other, with enough room in the middle to build a mike....
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The design consists of differential compound pairs of transistors with a common mode (floating) gain control connecting the emitters of the pair. The compound pairs of 2N4403 and BC549s are far more linear than any single transistor. The circuit is....