Electron-Coupled Oscillators

Posted on Feb 7, 2014

One of the outstanding problems in the design of vacuum-tube oscillators is that of keeping the frequency constant despite mechanical vibrations, temperature changes, voltage variations in the supply lines, and changes in the amount of power taken out of the circuit by the load. The effects of variable loading are greatly reduced by the use of electron coupling. Let us imagine that in the Hartley

Click here to download the full size of the above Circuit.

circuit of Fig. 14 B the actual metal plate is replaced by a grid of wires. The stream of electrons reaching this electrode increases and decreases in number at the frequency of the oscillating circuit in the usual manner. But, with a grid of wires rather than a solid metal plate, a part of this stream of fluctuating electrons passes through the " plate " and can be used in a later portion of the tube. It is as though we had a " virtual" cathode, emitting electrons, whose number varied from maximum to minimum periodically at a high rate. Of course it is impossible to heat and cool an actual cathode at high frequencies. Yet the combination of the Hartley circuit with a grid which acts as the " plate " serves the same purpose. In the circuit on the left of Fig. 29 A, the fluctuating electron current, which has passed through the grids, reaches the solid plate and passes on to the tuned circuit LC. When the periodic fluctuations of the electron stream correspond to the natural frequency of the tuned circuit, they serve to supplant the losses in this resonant or tank circuit and keep it in oscillation. An important feature of this arrangement is that the upper grid is operated at ground r. f. potential, and hence acts as a shield between the output or load circuit coupled to LC and the oscillating circuit itself. In this way, variations in the load current are prevented from reacting upon the oscillator circuit and changing...

Visit page

Leave Comment

characters left:

Related Circuits

Linear Resistance Meter

Most analogue multimeters are capable of measuring resistance over quite a wide range of values, but are rather inconvenient in use due to the reverse reading scale which is also non-linear

Linear Video Amplifier SECAM PAL and NTSC

Buffered video amplifier is used wherever the use of video player to the receiver / monitor TV with a long cable may cause a drop in signal amplitude and as a consequence, the deterioration in...

Liquid detector water sensor circuit

This is a very simple liquid detector that use a relay to open an evacuation van. You can use it for water or any liquid that conduct electricity. Use any.

Lithium Ion charger circuit using LM3632

Lithium Ion charger circuit design electronic project using LM3632 controller.

Logic Probe for Tri-state Logics

This is a simple circuit of Logic Probe for Tri-state Logics. This circuit can be built only in a few hours. Besides that, this circuit has some other.

Long-Range IR Transmitter

Most of the IR remotes work reliably within a range of 5 metres. The circuit complexity increases if you design the IR transmitter for reliable operation over a longer range, say, 10 metres. To...

Low-cost-frequency-counter

This counter uses a four-digit display, but with a flip of the range switch, it can display frequencies from 1 to 40 MHz, with a resolution of 100Hz. The MM74C926 CMOS IC contains a four-digit...

Low-frequency-tachometer

This tachometer lets you measure heartbeats, respiratory rates, and other low-frequency events that recur at intervals of 0.33 to 40.96 seconds. The circuit senses the period offm, computes the...

New Circuits

Zero consumption Anti-theft High power Code Switch for E-Bike Batteries

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....
Ultrasonic distance finder circuit

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....
Simple Metal detector circuit with CD4030

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....
Fully automatic watering circuit for flower pots

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....
Simple deep searching metal detector circuit

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....
Sub-Harmonic Bass Converter for Electric Guitars

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,....
Echo Depth Sounding Sonar for Boats

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....
100W HiFi Audio Amplifier Circuit

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....
Plant-Pot Water Level Indicator Circuit

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.....

Create NOW your QR MENU for your Restaurant / Hotel / Bar / Caffe,

Comprehensive ordering/paying features. fully personalized to suit your Business.

Update Anytime! Easy and Simple!

Popular Circuits

Simple Metal Detector DIY

LED 1 will light and the buzzer turns on when the coil is changing inductance. The setup is easy,...

40Mhz-universal-counter

This circuit can be used to measure frequencies up to 40 MHz. To obtain the correct measured...

From Crystal Sets To 405 Line television

A valve radio receiver in its crudest form is a frequency determining tuned circuit, (consisting...

serial ir transmitter

This is essentially the simplest circuit with additional indicator LED`s and appropriate resistor...

inverter circuit diagram

Double-ended working core square wave inverter transformer area product formulaBm is the maximum...

Automatic 12 Volt Lamp Fader

This circuit is similar to the "Fading Red Eyes" circuit (in the LED section) used to fade a pair...

160 METER VFO

Standard Colpitts oscillator Q1 with emitter-follower Q2 gives dependability and adequate...