rf circuit diagram
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rf remote control encoder and decoder
This document explains two RF 433kHz remote control chips specifically designed for remote control applications. The IC TWS-434, along with its encoder chip HT-12E from Holtek, forms a high-quality transmitter circuit, while the chip RWS-434, paired with the decoder IC...
Simple receiver with microvolt sensitivity
The three-transistor circuit costs less than $10 to build, uses commonly available components, and consumes less than 10 mA from a single 9V battery. By winding coil L1 as shown, the circuit can receive signals in the 5 to 15...
80 Watt stereo transmitter
This transmitter was designed from the ground up to provide very high sound quality, coupled with excellent frequency stability, reliability, etc. It can be used as a standalone transmitter to serve a medium-sized town, or as an exciter to drive...
Garage door open indicator
There are battery-powered wireless systems available, but the ones encountered would indicate that the door was open even if it was left ajar for ventilation. A system was desired that would alert when the door was fully raised. Additionally, it...
Remote antenna for 60 kHz (WWVB) reception
Inside the outdoor box where the loop is mounted, the amplifier circuitry is displayed. The four capacitors located at the lower-left corner of the perfboard are used to broadly resonate the receive loop. In the office building, which is a...
Beacon-transmitter
This transmitter is suitable for transmitter hunts, remote key finding, or radio telemetry in model rockets. It can be tuned to the two-meter band or other VHF bands by adjusting capacitor C1 and inductor L1. L1 consists of four turns...
TRF Radios
A small Medium Wave antenna from a walkman with digital radio and a variable capacitor (VC) with two sections connected in parallel from an old Russian radio (2x280pF). It has been noted that in areas with strong signals, optimal performance...
Transmitter-oscilloscope coupler for CB signals
To display an RF signal, connect LI to the transmitter and points A and B to the vertical plates of the oscilloscope. Adjust LI for minimum SWR and C3 for the desired trace height on the CRT. More: L2 consists...
Circuit diagramms of the 144 SBB/RX - Receiver
To comprehend the interconnections between the following circuits, it is essential to first review the concept chapter. It is at the discretion of the user to select one or two of these circuits for personal development. The discussion begins with...