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
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ith the transmitter. However, if you intend to use the complete transmitter and receiver combination as a `stand alone` unit, it will be necessary to use a suitable low-pass filter to reduce potential harmonics. A filter of this sort can be built into the transmitter, or it can be an outboard type used in conjunction with a small antenna tuner. What the individual constructor does of course, will depend on the size of casing and whether or not the project is built as separates or as one small unit. With the change-over switching described in the previous article, the transmitter can be used with any 1. 8MHz receiver. If you don`t have a suitable set, you can add a simple single board receiver of the sort described here. However, bear in mind that the receiver is not a DX model and it`s designed for using the Chatterbox combination in local a. m. nets. The receiver section is based on the TDA1072A a. m. receiver i. e. This is an inexpensive chip which performs all the functions of an a. m. receiver between the antenna and the audio stages. The TDA1072A`s sensitivity and signal handling capabilities are such that it`s suitable for this application. The i. e. also supports several features not used in this design. Some of the features are made available on the p. c. b. , should you wish to incorporate them in the receiver. For example, the chip provides an S-meter output, a muting facility and a buffered oscillator output for...
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....
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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....
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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....
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