This project was inspired by a sense of wanting to build something a little unusual rather than with the expectation that it would become a useful transmitter. At the time of writing I`m at the breadboarding stage and have yet to decide if I will keep the unit in its current form or dismantle it to re-use some of the parts in other projects. One of my friends egged me on to build this device and although the rather large size of the valve
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is more his enthusiasm, I did get to wondering if I could actually use this on air. The valve is a Russian made "GM100" directly heated triode. This valve will withstand anode voltages of up to 5 kV, pass currents of up to 1. 6 amps (!) and has an anode dissipation of 1 kW. The filament takes a massive 18 amps at 17 volts although the only slightly suitable transformer I have drives the heater to about 15. 5 volts which is still pretty bright. To give some idea of the scale, the tiny tube on the left (by the multimeters) is a 12AT7 double triode, the larger tube on the right hand is a 3-500Z, a modern 500 watt triode. The variable capacitor and inductor shown in the photograph are moderately big components, at least by UK ham standards, but are dwarfed by the huge tube. Having "short" wiring is obviously quite difficult on something so large but ferrite beads on the grid and anode leads seem to have prevented parasitic oscillations. To run this tube at full power much larger components would be required and the wooden frame would probably be a fire risk! The whole rationale behind this transmitter is to under-run the tube in the interests of frequency stability and longevity although the heater power consumption is a little excessive. The circuit I`ve used for this is identical to that of the 812 Hartley shown further down the page. At the time of writing, 20 watts of RF has been obtained at 1. 9 MHz with a 730 volt supply...
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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