This page covers several different regenerative receiver circuits that were used in the past, mostly from 1920s to 1940s. Connections are shown with electron tubes (vacuum tubes/valves), but FET transistors can be substituted with little or no changes. To those infected with radio bug, this page might be a useful resource. It shows different conne
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ction setups for tube based regenerative receivers. As such they might prove useful for new tube builds or FET/bipolar transistor implementations. Throughout, L1 is antenna coil, L2 main coil and L3 feedback "tickler" coil. Headphones H can be replaced with audio transformer or suitable RC combination for connection to next amplifier stage, in all circuits. R1 is around 1 megaOhm, C2 around 100 picoFarads. 1. Classic connection - plain inductive reaction. High frequency radio signal is coupled from antenna coil L1 to main tank circuit L2 - C1 used to select radio station. Triode is connected as grid demodulator (audion). Demodulated audio signal at anode is sent to headphones H. Positive feedback is achieved with tickler coil L3, feeding back part of high frequency energy from anode to grid circuit (coil L2). Regulation of positive feedback is done by change of L2 <-> L3 distance, or by L3 rotation. Coils L2 and L3 must have proper "polarity". If they are wound in the same direction (say clockwise on coil form) they should be connected as indicated on schematic. If positive feedback cannot be achieved, try swapping L3 ends. If it still doesn`t work, L3 is too far away from L2, or it has insufficient number of turns. For medium wave 540 - 1600 kHz reception, L1 should have about 5-10 turns, L2 around 80, and L3 40-50 turns of insulated or lacquered copper wire on cylinder with 30 mm diameter. If ferrite is used instead of...
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....
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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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