A simple radio receiver circuit is shown in Fig. 1. This receiver is designed for reception of signals of amateur radio stations operating in the SW band of 10, 15, 20, 40 and 80 meters. This direct-conversion receiver consists of a set of an input bandpass filters tuned to the middle frequency of the amateur bands, a broadband RF amplifier based
Click here to download the full size of the above Circuit.
on a transistor VT1, a diode mixer (VD1, VD2), a local oscillator (VT2) and a three-stage amplifier of audio frequency with high gain based on a transistors VT3-VT5. This amplifier is loaded with a headphones BF1. A switch SA1 is intended to switch between bands, it connects the filters to the input of the RF amplifier, and the mixer - to a corresponding resonant tank of the local oscillator. The local oscillator is tunable by a variable capacitor C27 and it generates an oscillations with a frequency twice lower than the frequency of received signals. A simple voltage regulator is based on the Zener diode VD3 and it is used to reduce a dependence of the local oscillator frequency of a supply voltage variation.
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.....
characters left: