This project uses just one tube. However, the tube chosen (13EM7) actually contains two separate triode structures. One is physically quite small, and is capable of a large signal gain but little power. It therefore makes an ideal preamplifier stage. The other section is larger, and ha
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s a lower voltage gain, but is capable of a significant amount of current. It therefore can deliver up to about two watts of power into a speaker load under the appropriate conditions. This tube was originally designed to be used in television sets. The small, high-gain section was typically used as the vertical oscillator, and the larger section as the vertical output stage. However, it also makes a splendid audio tube. If you think about it, linearity is no less critical in television sets than it is in high-fidelity audio. At the same time, there isn`t the "mystique" around television tubes that there is around so-called "audio" devices, so the price is a lot more reasonable than otherwise quite similar tubes such as, say, the Type 45. There are a few different variants of this tube which can be used. The 13EM7/15EA7 is functionally identical to the plain 13EM7. If you`re buying a tube for this project, either variant will be fine. If you have a "junk box" of tubes, but don`t have a 13EM7, you might have a look to see if you can find a 10EM7. This is the same tube, but with a lower-voltage filament. It can be used in this design if a filament dropping resistor is added (details later). The 6EM7 or 6EM7/6EA7 could conceivably be used also, but will be a bit more involved; for this reason this option is suggested only for more experienced tube equipment builders. Similarly, there are other tubes such as 13FM7 which would...
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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