RF Circuits
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The AM Tuned Radio Frequency (TRF) receiver, has a sensitivity of about 1 m V at tbe input for an audio output of "iz W. Capacitor C22 couples audio signals from the power line to the PC board-it must be rated at 600 Vdc. R8 will cause F1 to blow, if C22.... -
In the 100-kHz application from left to right, the coupling network feeds into the receiver ~section on the bottom of the chip. (The external components are summarized later.) The receive data output is pulled up via RPuLL ~ 10 K!l. A minimum current of 10.... -
Among the signals below 550 kHz are maritime mobile, distress, radio beacons, aircraft weather, European Longwave-AM broadcast, and point-to-point communications. The low-frequency converter converts the 10 to 500kHz LW range to a 1010 to 1550kHz MW range,.... -
The unit consists of rlamplifier Q1, local oscillatorQ2, and mixer Q3. The two bands are covered without a bandswitch by using an i-f or 3.5 MHz. The oscillator range is 7.5 to 14.5 MHz. Incoming signals from 4 to 11 MHz are mixed with the oscillator to.... -
The NE602, U1, contains oscillator and mixer stages. The mixer combines the oscillator signal with the input rf signal to produce signals whose frequencies are the sum and difference of the input frequencies. For example, a 7.5-MHz signal is picked up by.... -
A typical circuit at 20 MHz is shown. The crystal, which has an internal series resistance Rs of 14ohm, oscillates at its third harmonic. The diode clamp Dl and D2 provides a constant amplitude control. .. -
This application involves demodulation of a frequency-modulated subcarrier of the main channel. This popular example uses the PLL to recover the SCA (Subsidiary Carrier Authorization or storecast music) signal from the combined signal of many commercial FM.... -
The amplifier operates across the 2 -30 MHz band with relatively flat gaio response and reaches gain saturation at approximately 210 W of output power. Both input and output transformers are 4:1 turns ratio (16:1 impedance ratio) to achieve low input.... -
This amplifier utilizes a 2N6367 and a pair of 2N6368 transistors. The 2N6367 transistor is employed as a driver and is specified for up to 9 W (PEP) output. In the amplifier design the driver must supply on 5 W (PEP) at 30 MHz with a resulting !MD.... -
The only adjustments that require close attention are input, output, and neutralization. The 150-pF capacitor in the input line compensates for impedance mismatch. You tune for maximum signal transfer from exiter to final with an in-line meter or external.... -
The circuit has a frequency response ranging from 100Hz to 3 MHz; gain is about 30 dB. Field-effect transistor Q1 is configured in the common-source self-biased mode. Optional resistor R1 allows you to set the input impedance to any desired value;.... -
This wideband amplifier uses only five components. External signals enter pin 3 of IC1 via ac coupling capacitor Cl. Following amplification, the boosted signals from IC1 pin 1 are coupled to the output by capacitor C2. Capacitor C3 decouples the de.... -
The amplifier"s input stage is a dual-gate GaAs FET, which provides low input capacitance and high transconductance. The dual-gate structure accepts the signal on input 1. Input 2 controls the gain of the amplifier. The amplifier has a third input for use.... -
The oscillator is a standard UHF design which delivers about 10 mW at 1.2 GHz. R1 and R2 bias the base of Q1 to 1.2 V via 12. Collector current is set by R3 to about 30 mA. C2 couples the base of Q1 to the stripline circuit. Tuning is provided by CVl, and.... -
This receiver is capable of better than 1.5 p, VIHF sensitivity and uses MOSFET front-end circuitry with varactors to eliminate conventional bulky tuning capacitors. It also features high dynamic range, ceramic i-f filters requiring no alignment, and a.... -
The local oscillator is crystal-controlled and the i-f swing is hardly compressed. The deviation of the transmitted carrier frequency, because of modulation, must therefore be limited to prevent severe distortion of the demodulated audio signal. The.... -
The various signal frequencies are obtained for an incoming carrier centered at 49.86 MHz. The receiver employs double conversion, with i-fs at 10.7 MHz and 455kHz. Ceramic filters are used in both i-fs for selectivity and reduced"coil count. A quadrature.... -
This circuit is configured for the 80m band. The 365-pF, broadcast-band variable capacitor should have a vernier drive with a six-to-one ratio, which makes tuning easier by separating the stations on the dial. A good antenna and ground are also.... -
When digital data is transmitted over long lines (longer than 1 meter), proper transfer is often disturbed by the parasitic effects of ground level shifts and ground loops, as well as by extraneous noise picked up along the way. An optocoupler, such as the.... -
The design incorporates 30-0, 1/4;.. microstrip lines on the input and output. C3, C4, C7, and C8, along with Ll, form a pi network that matches the low-input impedance of the device to 50 0. C5, C6, C9, ClO, and 30-0 transmission line L2 form an output pi.... -
This circuit design is a class A amplifier employing both ac and de feedback. Bias is stabilized at 15 mA of the collector current using de feedback from the collector. The ac feedback, from collector to base, and in each of the partially bypassed emitter.... -
This amplifier provides 140-W PEP nominal output power when supplied with input levels as low as 3 W. Both input and output transformers have a 4:1 turn ratio and a 16:1 impedance ratio to achieve low input VSWR .. -
This circuit functions as a wideband adjustable AGC amplifier. With an effective bandwidth of approximately 10 MHz, it is capable of handling rf input signal frequencies from 3.2 to 10 MHz at levels ranging from 40 mV up to 3 V pk-pk. AGC action is.... -
This circuit utilizes the MRF123 TMOS power FET. The MRF134 is a very high gain FET that is potentially unstable at both VHF and UHF frequencies. Note that a 68-0 input loading resistor has been utilized to enhance stability. .. -
This 60-W. 28-V broadband amplifier covers the 225-400 MHz military communications band. The amplifier may be used singly as a 60-W output stage in a 225-400 MHz transmitter. or by using two of these amplifiers combined with quadrature couplers, a 100-W.... -
This transmitter consists of a keyed crystal oscillator/driver and a high efficiency final, each with a TMOS Power FET as the active element. The total parts cost less than $20, and no special construction skills or circuit boards are required. The Pierce.... -
This transmitter is capable of two levels of rf power. For low-power wireless video, like in a house or office, where simultaneous monitoring of program material is desirable without cumbersome hookups, 1-30 mW is available. For longer ranges up to several.... -
This is a sensitive, mini-powered FM transmitter consisting of an rf oscillator section interfaced with a high-sensitivity wide passband audio amplifier and capacitance microphone with built-in FET that modulates the base of the rf oscillator transistor..... -
This is a little transmitter that could be put into a plastic Easter egg. It delivers approximately 1 W of measured rf output into a 50-0 dummy load, and creates no heating problems with the circuit. The crystal is a series fundamental type, and the power.... -
In a half-duplex system, information can flow in both directions, but only one direction at any given time. The conventional method of building a half-duplex link requires a separate emitter and detector, connected with directional couplers, at each end of.... -
The FM Snooper is an FM transmitter that radiates a continuous wave whose frequency is altered according to the sound waves striking the microphone. An ordinary FM broadcast receiver detects the transmitter"s output carrier. When 9-V battery, B1, is.... -
The range of this transmitter is about 50 feet with a short whip antenna. The tone generator, is made up of a unijunction transistor, Q1, and R1, R2, R3, and C2. Transistor Q1 pulses on and off at a rate determined by the time constant of R1 and R2,....
New Circuits
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This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of.... -
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is.... -
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to.... -
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This.... -
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the.... -
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,.... -
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the.... -
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power.... -
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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