Rongge

SIMPLE RADIO FREQUENCY REMOTE SWITCHING CIRCUIT RF TRANSMITTER SECTION Today we are going to discuss about the simple RF (Radio Frequency) Transmitter and Receiver circuit. RF(Radio Frequency) is a High Frequency signal commonly used for communication applications, due to its high frequency we can transmit signal to a sufficient distance (about 300 Foots) without attenuation. Here, the simple RF switching circuit is used to turn ON and turn OFF an LED (For Demonstration) you can replace the LED with a switching RELAY and control any appliances. Read More.....

This basic circuit is simple to create and the tool's are not critical . Most of them can be found in your junk parts box . The L1 antenna coil can be made by close winding 8 to 10 turns of 22 gauge insulated hookup wire around a 1/4 inch form such as a pencil . You can exeprement with the size of the copile and the number of  turns to see how it affects the frequency and singnal out put of the oscilatter . You ought be able to pick up its signal with a standard FM radio receiver . The signal in ought be coupled by a disc capacitor of about 0.1 uF to stage in main of it . Author            Saifullah soomro

The circuit above is a dummy load capable of handling up to 10 watts of RF power for a few minutes, and its impedance is 50 ohms. It is constructed with 10 parallel resistors 560 ohms per 1 watt, R1 to R10, a voltage divider R11-R12 and a rectifier D1-C1. Its output voltage in a voltmeter which can be connected to measure the RF power.

Description  This is a simple type remote control by using RF communication without microcontroller. In this project a remote has been designed for various home appliances like television, fan, lights, etc. It gives lot of comfort to the user since we can operate it by staying at one place. We can control any of the appliances by using this remote within the range of 400 foots. In this project consist of two sections, transmitter (remote) and receiver section. Whenever we are pressing any key in the remote it generates the corresponding RF signals, and these signals are received by the receiver unit. ASK transmitter and receiver is used as transmitter and receiver. HT12E, HT12D encoders and decoders are used in this electronic circuit. The block digram of the whole circuit is given below.  Appliance Control Block Diagram Remote Section In remote section consist of an encoder (HT 12E) and a ASK transmitter. The encoder generates 8 bit address and 4bit data. We can set the addre...

Preamplifier for RF Sweep Generator Circuit diagram. The RF sweep frequency generator (‘wobbu-lator’) published in the October 2008 issue of Elektor has a receiver option that allows the instrument to be used as a direct conversion receiver. This receiver does however have a noise floor of only –80 dBm, which really should have been –-107 dBm to obtain a sensitivity of 1 µV. So, for a good receiver sommore gain is required. A wideband amplifie however, generates a lot of additional noisas well and as a consequence will not resuin much of an improvement.  As an experiment, the author developed a selective receiver with a bandwidth of about 4 MHz. Because a gain of at least 35 dB is required, the preamplifier consists of two amplifying elements.  The input amplifier is designed around a dual gate MOSFET, type BF982. This component produces relatively little noise but pro-vides a lot of gain. The output stage uses a BFR91A for some additional gain. Preamplifiers where both the ga...

This basic circuit is simple to create and the tool's are not critical . Most of them can be found in your junk parts box . The L1 antenna coil can be made by close winding 8 to 10 turns of 22 gauge insulated hookup wire around a 1/4 inch form such as a pencil . You can exeprement with the size of the copile and the number of  turns to see how it affects the frequency and singnal out put of the oscilatter . You ought be able to pick up its signal with a standard FM radio receiver . The signal in ought be coupled by a disc capacitor of about 0.1 uF to stage in main of it .       

The RF attenuator is used to attenuate an RF signal that can be output from a generator, transmitter or receiver. This RF attenuator can be used without problems at a frequency of up to hundreds of MHz The key must be of good quality and with low inductance resistors. Table 1 shows the values ​​of the resistors impedance attenuator with 50 and 75 ohms. read full via Scheme RF Attenuator Circuit Diagram