RF Receiver Circuits
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This is a compact three transistor regenerative general coverage receiver with fixed feedback. It`s based on the principle of the ZN414 only much higher coverage. The sensitivity and selectivity is relative good (especially on the LF and MW bands) as can be.... -
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This is a Crystal Receiver using 741 IC chip. Frequency range is between 500-1600Khz... -
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This is a very sensitive 50Mc converter allowing you to receive the entire "Magic Band" (50Mc...52Mc) on your general coverage receiver (28Mc...30Mc). It receives all types of modulated transmissions. It all depends on the receiver used. I`ve tested this.... -
This small receiver with reduced range (weight 9g, dimensions 32 x 25 mm) is suitable for slow-flyer, little boats, etc... -
IR detector diode D1 intercepts the IR signal at around 40 kHz and feeds it from U1, a high-gain preamp, to PLL, U2, a 4046 configured to serve as an FM detector. U3 is an audio amplifier that feeds a pair of headphones or a speaker... -
With this simple project, you can have balanced lines too, simply adapting the unbalanced inputs and outputs of your hi-fi gear to become balanced, and then back to unbalanced at the other end. You can even be extra cunning, and power the remote converter.... -
The FM broadcast band was moved immediately after World War II from its original spot just below 50 Mc to the present 88-108 Mc band. Hallicrafters was one company to offer receiving converters for those who had the old FM radio sets. The offerings....
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This is the simplest possible design. The local oscillator of the receiver is adjusted slightly so that its second harmonic can be used for mixing. RF leakage from the local oscillator is sufficient to drive this crystal diode mixer, which has an output at....
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This is a one tube (6J5) plus diode (1N34) circuit that converts any 8 Mc of the new FM band to the old FM band. It is assembled on a U-shaped piece of aluminum and mounted inside the radio set. I built one using old parts and carefully followed the....
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Here is my design for a modern receiving converter for pre-war FM sets. Accordingly, this article presents a design for listening to present day FM stations on a prewar FM set based on a MOSFET transistor and a TTL (transistor-transistor logic) packaged.... -
This circuit has `suffered` a lot of modifications over its long life... Even the lettering on the integrated circuit was partially erased of the years. The main motive of the mods was not that the circuit didn`t work right, but were several tries to add.... -
Here is a simple radio that is easy to build and inexpensive. In fact, you probobly have all the parts you need in your junk box. You`ll be suprised at the great reception with this little set... -
The circuit is a divider by 64 used in many RF applications like as satellite receiver, digital tuners, frequency counters, PLL, etc. The heart of circuit is an IC named SAB6456, but you can use SDA2101 or other equivalent chips. Each output is NOT of the.... -
The circuit is an VXO with buffered output. It operates on 20-meter amateur radio band with the output voltage about 0.2 Vp-p. The crystal frequency is pulled by tuning the variable capacitor CV1 about 36Khz with only one crystal (Y1), and 250Khz by using.... -
This reflex radio project was inspired by Robert Bazian 's design. His reflex radio is the "darndest" thing I have seen and his spectacular results inspired me to come up with my own version! These designs are similar to two-transistor circuits used in some.... -
The regen is basically an oscillator circuit with a gain control that allows the user to adjust the feedback to a point just below oscillation or, quite often, just above the critical level such that a small oscillation is present. The typical regen uses a.... -
Modulation Monitor is a simple and useful circuit for hams. You can listen to on air transmission from your rig and be sure about the quality of the transmission. It requires no direct connection with the transmitter. In the prototype, headphones of 1K.... -
The source connection is tapped into the tuning coil low down, as a means of impedance matching with the headphones and acts as the anode, while the drain connects with your headphones as the cathode, to complete the detector part of the circuit. According.... -
The coil on the left is coil#1, and has 17 taps. The other coil is coil #3. The vertical strips are the lath material, screwed to the 1 foot long base. Holes drilled in the ends of the lath hold the dowel rod; it can be removed to change coils. The.... -
Building a foxhole radio is rewarding and the basic setup is very simple. It is, however, difficult to adjust, and it may take several attempts to find a proper razor blade for the detector. This is a project that requires patience and much trial and error,.... -
The basic MK484 (Replacement for the ZN414) connected in its minimum configuration as a radio receiver for the A.M. Broadcast band and the upper half of the United States' FCC Part 15 Lowfer (1600-1750 meter) band. Its a circuit straight out of the.... -
his coil is home-made. It is actually a single layer 'tapped' air core coil. Please refer to my special section on how to make the DRAIN Coil. Once it is made, the tapped leg goes into the middle hole (Refer to CHART I), but make sure you have the coil.... -
Based on Valvo FD-1A module, TBA120, and MC1310. Operation of the receiver is based on the phase locked loop principle. The FD-1A contains an RF amplifier, oscillator and mixer (made with BF324, BF451 and BF324 transistors, respectively). Tuning is performed.... -
Two conventional amplifier stages built with SF215 transistors are linked by ceramic 10.7MHz IF filters, and followed by an FM demodulator built with a TBA120T i.c. Straight from the databook. Output goes via a 100k log potmeter (not shown) to the audio.... -
For this radio, which I repaired for someone, I made this DIY VL1. Later I found the real tube... -
The Nora K5W is a German radio from about 1929/1930. Is uses the tubes: 2x REN804, 2x REN1004, RE134 or RE604, RGN1054... -
A MW AM radio like those you buy, or used to buy. Use just BC549 trannies, with the BC559 complement being allowed in the audio output stage. Buying RF antenna coils, oscillator coils and intermediate frequency transformers would be cheating - wind your own..... -
The diagram of detail of Fig.2 gives additional precise details: The signal HF collected by the antenna is amplified by T1, framed reel S of agreement L1 and L2. To vary the profit of T1, it is enough to vary its supply voltage. Here it passes from 4v to.... -
The quartz QZ1 of the preceding receivers which set the work frequency is not on the market any more. It is replaced by a locking phase loop allowing the free choice of an unspecified frequency on the band used, either the 41, or the 72 MHz. The step.... -
This receptor is born of our annoyance against the irritating problem of Quartz: With the RX21, completed research of cut crystal for your personal rating, you have with him, access to ALL band frequencies, in steps of 5 kHz ! Desiring to make this universal....
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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