Fortunately, Dodd`s 1909 receiver has survived. It was found among the many parts that were in various boxes that I had purchased at the yard sale. The pieces were identified from the 1909 Station photo. Many of the 1909 Station parts were used in the construction of Dodd`s 1912 station. The most obvious component is the helix that changed very little in its incorporation in the 1912 station. I restored the 1909
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Tuning Inductance in 2009 and it, along one of the home made detector stands and the single Kellogg earphone that Dodd is using in the photo, is now on display in the Museum. Since the inductance (and receiver) is so primitive, I have also included a copy of this photograph in the display so viewers can recognize that the components they are looking at is actually a 1909 receiver. The Transmitter Basics - Dodd`s 1912 station uses what was called a Damped Wave Spark Transmitter. The actual radiated signal is in the form of a pulsating wave train made up successive damped wave oscillations at a radio frequency determined by the LC of the Sending Condenser and the Helix. Damped wave means that each successive wave peak in each damped wave oscillation pulse is of reduced amplitude compared to the proceeding wave peak. An ideal decay or decrement of the damped waves would produce strong RF signals that could be copied at a great distance. The damped waves were created in the following manner. The Spark Transformer provides a high potential AC that is allowed to charge a Sending Condenser on the increasing positive voltage of the AC. When the charge voltage reaches a high enough potential, the insulating properties of the Spark Gap break down and the gap arcs over which effectively removes the transformer secondary from the circuit by a temporary short. However, the Sending Condenser then is discharged into the Helix. At this...
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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