This Hartley oscillator was built on the remains of a single tube Hartley using a single 45. The original circuit I constructed was one that was published in a 1932 QST article by George Grammer. As it turned out, both of the 45s I had were weak, so the oscillator only would run when it was loaded very, very lightly. I did, however, have a good 10
Click here to download the full size of the above Circuit.
triode, so I decided to change the value of the grid leak and the element voltages accordingly, and stick a 10 in the circuit. The 10 was a very popular tube in the late 20`s and early 30s for use in simple amateur radio transmitters. Sterlings "Radio Manual", second edition, 1929, has a section devoted to a shunt-fed hartley oscillator using a 10 triode. This same book, incidentally, has a section devoted to a simple three tube regenerative receiver, using tube base coils. You can build a complete 1929 station with the info in this book! Anyway, this tube oscillated easily and I was able to get 5 watts, output, when loaded, using 300 VDC on the plate. But, on key-up, the tube drew a slight amount of current, which turned out to be a parasitic oscillation. I was, however, quite happy with the output power and efficiency of the 10 in this circuit. My success with the shunt-fed design using 27s, shown elsewhere on this site, convinced me to re-build the Grammer Hartley using a 10 in the shunt-fed configuration. I wanted to change my original wire tank coil with more period-looking copper tubing anyway. So, here is the schematic of the single 10 Hartley oscillator: I built the circuit breadboard style on a piece of poplar. The front panel is a kind of acrylic product that I bought at the local electronics surplus store. It sort of looks like bakelite, which was the appearance I was after. The vintage National Dial I picked up...
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.....
characters left: