To me the E1T counting tube is unmistakably one of the most intriguing tubes ever made. It was invented and developed into a product by Philips in the period 1946-1954. On one of my other pages I have posted an in-depth study of it`s origins. It has long been my whish to build a clock with this wonderful device. One of the problems of making a clock from this tube is it`s limited lifetime.
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The E1T was designed for high-speed counting in measurement equipment. This was achieved by using an electron beam as opposed to a glow discharge as used in the competing decatron. This implied the use of a filament heated cathode, and unfortunately even the best filaments have a limited life expectance of ca. 10. 000 hours (1. 2 year). One of the ways to improve the life expectancy is to reduce the filament temperature. Obviously this will reduce the emission, and hence the beam current. It appears that for this application, where only low speed counting is required, a lower beam current is no problem at all. The other obvious measure to improve the life time of the tube is to simply switch it off when it is not used. In general, the frequent on/off switching of filament heated tubes is not a good idea. A cold filament has a significantly lower resistance than a heated one. This will cause a high start-up current resulting in high mechanical stresses during the heat-up phase. This is the reason that many tubes (and light bulbs) die the moment they are switched on. In this clock the filament is not completely switched off, but kept heated at a very low level, resulting in strongly reduced thermally induced stresses. Two mechanisms determine when the tube is actually switched on and off. In the first place the user has to select one out of eight profiles upon initialization. Each of these profiles determines during which...
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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