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RF Receiver Circuits
RF Receiver Circuits
VFO stabilization with 2N4416
The coil is about 25 turns #28 wire on a T-44-6 core, tapped at about 5 turns. I'm too lazy to open my VFO and count it for you -- besides, you'll probably have to tweak it yourself with your available components. Once the turns are squeezed to the right place to adjust the tuning range, a bit of Q dope holds them in place. This is built on a...
LW, MW and SW bands Receiver
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 expected with this "simple" design. The reception on the broadcast bands, LW(longwave)...
MW/sw Radio RECEIVER
No description available.
MW Enhanced Crystal Receiver using 741 IC
This is a Crystal Receiver using 741 IC chip. Frequency range is between 500-1600Khz.
Direct Crystal radio receiver examples
No description available.
50 MHz converter
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 project on a allmode Yaesu FRG-100 receiver. Within certain limits you can change the output...
RC 4-Channel FM receiver
This small receiver with reduced range (weight 9g, dimensions 32 x 25 mm) is suitable for slow-flyer, little boats, etc.
42 Mc Band to 88 Mc Band
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 included a one-tube converter that fits inside a console and draws power from the audio output...
Simple FM Converter
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 the 4.3 Mc IF frequency of the receiver. It is remarkably simple and apparently worked...
Tube FM Converter
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 article. It works!
Modern FM Converter
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 oscillator. Someone else might have done it with vacuum tubes, but this design suits me fine....
Tunable IF with TDA7000
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 some kind of frequency indicator to the receiver. The left RCA plug and associated...
crystal Op Amp Radio
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.
Simple Transistor Reflex Receivers
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 ancient Japanese "Boys Radios" except that the inter-stage transformer directly drives...
Regenerative AM Receivers
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 tapped coil or additional windings to connect into the tuning tank and the tuning...
HAM Modulation Monitor
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 impedance are used. If you want to use ordinary low impedance head phones, connect a suitable...
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 to the experts on the net, much success has been enjoyed by one and all, and there's a lot...
Selective Frequency Crystal Radio
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 bottle caps are the knobs of the two polyfilm rf tuner capacitors, which are stuck to the...
Foxhole crystal radio
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, but it will pay off once it begins to work. It will help to be versed in the construction...
AM reciever with MK484
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 application note and I have fount it to be useful on the bench. Even more convenient that using...
FM Receiver circuit
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 with four varicaps (BB104). There is an additional AFC diode which allows voltage...
FM radio circuit
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 stage. (NB SF215 transistors can be replaced by BF240, BF241, BF254, BF255, BF594 or BF595)....
CW Radio with Tubes
For this radio, which I repaired for someone, I made this DIY VL1. Later I found the real tube.
Old German radio with Tubes
The Nora K5W is a German radio from about 1929/1930. Is uses the tubes: 2x REN804, 2x REN1004, RE134 or RE604, RGN1054.
HF reciever with MC3362
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 0V, the varying profit of +10 dB with - 10 dB, is 20 dB on the whole. It is far from...
PLL 41MHz reciever with 68HC711D3
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 between channels is 5 kHz, giving us 101 frequencies in 72 MHz and 41 in 41 MHz. In practice,...
ALL band reciever using MC3362
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 receiver, it not only gives you the choice of frequency, but also the direction of the...
41-72MHz micro-receiver ( MC3362 )
This receiver weighs about 6 g, used in 41 and 72 MHz, met a great success with readers of the magazine. The RX22 is the subject of these lines is improved RX20. Adding a preamp-HF improving sensitivity. Establishment of an automatic gain control of this amp. Integrated voltage regulator. Power Connectors and embedded servos. Using a MC3362DW...
RF Recieving Amplifier for 40MHZ
The sensitivity of receiver it is possible to increase itself considerably, if is interfered, between this and his aerial, a amplifier RF. The amplifier of circuit, does not use in resonant circuits and for this is suitable, so much for mid waves, what for the low waves, up to the 40 MHZ. The gain his it is the order 20db and it consumes 7mA,...
AM To FM converter
This circuit can be used to recieve AM stations in an FM radio. Is a regenerative circuit that samples AM signals of all frequency and retransmits them in the FM band or in TV band.
PC FM radio
Stabilised tendency of catering: Vcc=9~12V. Frequency of reception: 88~108MHz. Consumption: 100mA. If you know some language of programming as C ++, PASCAL, VISUAL BASIC, DELPHI etc you can write a program which will send in the parallel door (378 I) of PC a number from 0 until 255 checking thus the tendency of expense of simple D/A of...
30m Band Receiver
The direct conversion receiver described consists of only a bandpass filter, mixer IC, VFO and audio filter. With only 22 parts, this simple circuit should take a few hours at the weekend to construct. For extra simplicity, eliminate L1 & C1 and connect C2 to the slider of P1. The oscillator section of the NE612 is configured as either a...
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Ultrasonic distance finder circuit
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 measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
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 find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
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 circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
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 circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
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, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
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 calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
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 supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
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. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
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