Most models produced in the 30s rely on very similar circuits; in particular the RF section of most sets relies on the same LW-MW-SW scheme while the differences between different sets are based on the presence or absence of the variable selectivity control, on more or less sophisticated tone controls and on the output stage. Some of these sets relied on European
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tubes (typically AK1, AF2, E444, E443H, 1561) or on American ones like 6A7, 6D6, 75, 42 and 80; some sets, like the SV13, used a mix of European and American tubes (AK2, 78, 75, 42 and 80). The SV3 was an high end model based on the European set and was endowed with a variable selectivity control mechanically coupled with the tone control. The unit described in this note was almost untouched; the only substitutions concerned one electrolytic capacitor and the power cord. All other components were the original ones and also the tubes were original and characterized by the lead seal that testified the payment of Italian taxes; they were also perfectly efficient, with the exception of the E443H whose filament was interrupted. Because of the high quality of all components it was expected that only a very limited number of substitutions would have been necessary; this was, in fact, the case but some other aspects called for a substantial amount of work. This note describes the points that, according to my experience, require more attention. To shorten as much as possible the length of the note, these points will be treated as separate items of a list. 1) Restoring the wiring. Differently from many other receivers produced in the same years, most of the SV3 wiring was based on rubber coated wires. Some wires were of the stranded type, others were solid and, to complete the picture, several colors were present for both types:...
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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