By taking advantage of certain characteristics of superhet action not normally used, it is possible with one pair of coils to cover both the 80- and 40-meter ham bands as well as ranges where commercial point-to-point c. w. and shortwave broadcast signals may be found. ”Donald H. Mix, W1TS, `A Beginner`s Four-Tube Superhet Receiver, ` QST, March 19
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50 CE Minimizing reception at the image frequency is fundamental to useful practical application of the superheterodyne principle ”unless the image happens to lie in another amateur radio band, and you want to receive it. This page explores the band-imaging receiver topology popularized in the 1950s by Don Mix, W1TS, and Byron Goodman, W1DX ”a design approach that uses a single local-oscillator tuning span to receive either of two bands without oscillator-tank switching, each band the image of the other. We see its pre-echo in George Grammer, "A Two-Tube Superhet, " QST, February 1941 CE, pages 12 15 and 92: In a simple regenerative-detector-behind-a-mixer receiver with a 1. 6-MHz intermediate frequency (IF), the same plug-in oscillator coil is used to tune the ranges 5. 4 10. 0 and 9. 5 14. 5 MHz. Wrote Grammer: It will be noted that the same oscillator coil, D, is used for two frequency ranges. This is possible because the oscillator signal is placed on the low-frequency side of the signal on the higher range. This not only avoids winding a second coil, but also gives somewhat greater stability at the highest-frequency range. . . . A word about images. The receiver will, of course, respond to signals either 1600 kc. higher or 1600 kc. lower than the oscillator frequency. The unwanted response, or image, is discriminated against by the tuning of the r. f. circuit. On the three lower-frequency ranges, when it is possible to...
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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