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AM Radio Circuits
AM Radio Circuits
VHF to AM Converter Circuit
There are many people who want to listen whats going on in VHF 108 - 132 MHz. This vhf am converter converts a band between 106 and 150 MHz, so you can lis..
The General Electric XT-1-A AM transmitter
Back in the day when AM was king, no expense was spared on transmitting equipment. I remember the GE BTA-25 transmitter from the same era, it was build like a tank. Once, while we were repairing the Harris MW-50A main transmitter, the old GE burped, sputtered and threw an IPA overload, then returned to air. I looked in the IPA cabinet and found...
This is a compact three transistor, regenerative receiver with fixed feedback. It is similar in principle to the ZN414 radio IC which is now replaced by the MK484. The design is simple and sensitivity and selectivity of the receiver are good. All general purpose transistors should work in this circuit, I used three BC549 transistors in my prototyp
Direct Conversion AM Radio
A 0th-level attack at designing a direct conversion AM radio receiver. "Direct conversion" means we use a mixer (which just multiplies two signals) to downshift the radio frequency signal to baseband (audio) frequencies. I still don`t really know how to couple the antenna into the circuit, how to use a crystal oscillator or a mixer chip, or lots o
AM Transmitter Circuit
Hi-fi AM detector
A modification to David Knight`s linear detector circuit. I wanted to build a "hi-fidelity" AM receiver and needed an ultra-linear AM detector for it. Here is the circuit I came up with: Note that I eliminated the meter circuit, and removed a lot of the bypass caps. I now have a circuit that has a finite quiescent current at the output te
the Poppet 500 milliwatt AM transmitter
The Poppet" is a half-watt AM transmitter designed by Mr. Doug Gibson of England. The original design was published in issue 84 of SPRAT, newsletter of the GQRP Club. The version shown here incorporates changes suggested by Steve Hartley and others. Although it was designed to work with a microphone and to be used in the 160 meter band (1800-2000
A simple AM modulator
An AM modulator for the MW band that will allow hearing the music of a CD or MP3 player during daytime on such radios. This is not a transmitter: the output power is very low (only 10mW) and is intended to be connected to the antenna input of the radio, or to be closely coupled with it. Amplifying the signal would be a bad idea, since...
AM FM Simultaneous Transmitter Using Digital IC
ZN414 Portable AM Receiver circuit
Designed around the popular ZN414 ic this receiver covers the AM band from 550 - 1600 KHz with the values shown. For Longwave the coil needs to be changed. Use one from an old MW radio to save time. The ZN414 is a tuned radio frequency designed and incorporates several RF stages and an AM detector. It is easily overloaded and the operating...
Micro Power AM Receiver circuit
This is basically a crystal radio with an audio amplifier which is fairly sensitive and receives several strong stations in the Los Angeles area with a minimal 15 foot antenna. Longer antennas will provide a stronger signal but the selectivity will be worse and strong stations may be heard in the background of weaker ones. Using a long wire antenn
Simple AM Transmitter circuit
There are not many AM transmitters that are easier to build than this one because the inductor is not tapped and has a single winding. There is no need to wind the inductor as it is a readily available RF choke (eg, Jaycar Cat LF-1536). To make the circuit as small as possible, the conventional tuning capacitor has been dispensed with and fixed...
555 Am TransmitterCircuits
I have two ICM7555 CMOS 555 timers, and I was wondering if anyone has any good am radio transmitter circuits that incorporate two (or one!) 555 timers..
Mitsubishi: I am putting a hydraulic thumb on my excavator heads
The excavator is Mitsubishi MS280. The problem is they are not sure how to excite the pump, I want to put an electronic proportional control valve in the old girl. If your familiar with this era of Mitsubishi`s could you let me know and I will give you as much detail as I can. I will try to explain what I have and what I believe is happening. The
Free-Power AM Radio
Here`s something that might intrigue you Crystal Radio builders out there: A one-transistor (Silicon, yet!) AM broadcast receiver that derives its power from ambient AC hum and `spherics [static crashes]! Gotta give credit when I can: The germ of the schematic was borrowed from Darryl Boyd`s "Stay Tuned" website which features over 170 articles an
Simple AM Transmitter
There are not many AM transmitters that are easier to build than this one because the inductor is not tapped and has a single winding. There is no need to wind the inductor as it is a readily available RF choke (eg, Jaycar Cat LF-1536). To make the circuit as small as possible, the conventional tuning capacitor has been dispensed with and fixed 22
Class E AM Transmitter for 1710 kHz
A 200-watt class-E AM transmitter used for non-sanctioned broadcasting on 1710 kHz. Negative peak limiter, over-modulation indicator, linear scale directional wattmeter, power supply and antenna circuits (schematic diagram) are also shown..
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 capacitor
National Radio Institute (NRI) AM radio kit
This National Radio Institute radio kit covers the AM broadcast band from 550 to 1700 KHz. The set was designed to be constructed as part of a radio course taught through NRI. In contrast with some other correspondence course kits such as a later NRI chassis, it uses a safe transformer power supply. Tubes are a 6BA6 RF amp, 6BE6 converter, 6BA6...
Notes on the Wenzel low power AM transmitter schematic
In many discussions of LPAM transmitter design you will hear or read references to "the Wenzel circuit" or "the Wenzel transmitter. " These refer to the clever transmitter design downloadable at During the mid 1990s and early 2000s, this was the best available AM transmitter circuit if you wanted to build something yourself for around-the-house...
C-Quam AM Stereo Transmitter Using Valves
Tube AM Modulators
AM Transmitter 10W
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AM Transmitter 25W
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Wideband AM Radio Receivers
1.8MHz AM transmitter and receiver
Before starting on the receiver side of the` Chatterbox`, we ought to take a final look at the transmitter itself. The Chatterbox transmitter is built separately, because many constructors will want to use it in conjunction with an existing receiver on 1. 8MHz. It`s been assumed that an existing antenna tuner and low-pass filter unit will be used w
FM Radio Circuits
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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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