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This circuit is an add-on unit for radio receivers that lack band-position display. The circuit presented here can show up to nine bands. It also incorporates a novel feature to make the display dance (blink) with the audio level from the receiver. The power-supply for the circuit can also be derived from the radio-set. The conversion of selected channel to BCD format is achieved using diodes D1 through D15 in con-junction with resistors R4 to R7. The voltages developed across these resistors (R4 through R7) serve as logic in-puts to BCD inputs of BCD to 7-segment de-coder IC1 (CD4511). Circuit diagram : Radio Band Position Display Circuit Diagram When all switches are in  ‘off’ state, the volt-age across resistors R4 through R7 is logic zero, but when any of the switches S1 through S9 is slided to  ‘on’ position, the output across these resistors changes to output proper BCD code to represent the selected channel. This BCD code is converted to 7-segment display by IC1. By this arr

Circuit diagram: AM FM radio reciver circuit diagram Datasheet for TDA1083: Download

Circuit Diagram  Description This is basically a crystal radio with an audio amplifier which is fairly sensitive and receives several strong stations in the Los Angeles area with a minimal 15 foot antenna. Longer antennas will provide a stronger signal but the selectivity will be worse and strong stations may be heard in the background of weaker ones. Using a long wire antenna, the selectivity can be improved by connecting it to one of the taps on the coil instead of the junction of the capacitor and coil. Some connection to ground is required but I found that standing outside on a concrete slab and just allowing the long headphone leads to lay on the concrete was sufficient to listen to the local news station (KNX 1070). The inductor was wound with 200 turns of #28 enameled copper wire on a 7/8 diameter, 4 inch length of PVC pipe, which yields about 220 uH. The inductor was wound with taps every 20 turns so the diode and antenna connections could be selected for best results which tur

This is a Small Circuit Multiband Radio -Transmitter CW for who wants to learn more about radiofrequency, mainly operating principle from radios transceivers multiband, That circuit consists of a frequency oscillator RF, which is the main component us transmitters and radio receivers.  He oscillates for high frequency, he is called variable frequency oscillator or VFO, their frequency may vary of 5.2 MHz to 15 MHz, depending the coil chosen and signal can be received in the band shortwave by any receiver radio.In S1 is used a switch type bell, but can-if use a handler CW, these used by radio amateurs. How antenna should-if use a the type dipole from 1/4 wave.

AM Radio Circuits AM radio began with the first, experimental broadcast on Christmas Eve of 1906 by Canadian experimenter Reginald Fessenden, and was used for small-scale voice and music broadcasts up until World War I. AM radio technology is simpler than Frequency Modulated (FM) radio, Digital Audio Broadcast (DAB), Satellite Radio or HD (digital) Radio. An AM receiver detects amplitude variations in the radio waves at a particular frequency. It then amplifies changes in the signal voltage to drive a loudspeaker or earphones. The earliest crystal radio receivers used a crystal diode detector with no a mplification.  As a result, many broadcast stations are required as a condition of license to reduce their broadcasting power significantly (or use directional antennas) after sunset, or even to suspend broadcasting entirely during nighttime hours.  Medium-wave and short-wave radio signals act differently during daytime and nighttime.  However, in the late 1960s and 1970s, top 40 rock an

This is an AM radio power amplifier circuit. What is different with other general amplifier is that this circuit has a low-pass filter (passive type), built using R1C1 to limit the input-output frequency response. Additionally, a ferroxcube K5-001-001/3B with 3 turns of wire is used as ferrite bead  at output filter. All components should be spaced very close to  the IC.  The ground and speaker lead must be twisted tightly. The supply lead and supply ground also must be twisted very tightly. Here is the schematic diagram of the  circuit.  Audio Power Amplifier for AM Radio Circuit Diagram