What Must todo

Just as in the transmitter circuit, the series of FM Wireless Microphone Receiver Hi Fi also uses an FM audio receiver module. Module used in the circuit FM Wireless Microphone Receiver Hi Fi has a good feture, namely audio FM receiver module has a function that is able to muffle the noise squel. Audio FM receiver module that is used in FM Wireless Microphone Receiver Hi Fi also does not require a lot of supporting components in the RF signal reception.

Audio FM receiver module only requires a 5 volt DC voltage source and a potentiometer P2 to set the threshold level of noise that will be muffled. Voltage source to an audio FM receiver module is also to go through the regulator is good, because if the quality of resources kuran it will generate noise. At the output line installed capacitors C3 and C4 as a couple and compensator for output in accordance with the amplifier or mixer (100mV rms).

To provide an output signal according to the needs and stable output signal audio FM receiver module on FM Wireless Microphone Receiver Hi Fi is fed to an audio preamplifier which uses IC TLC272. Levelk audio signal set by potentiometer P1. As a voltage regulator for power source circuit FM Wireless Microphone Receiver Hi Fi LM7805 regulator IC is used.

source: extremecircuit.net

Contrary to what some radio experimenters think, a bipolar regenerative design can be made to work efficiently. The major concern is the low input impedance of the detector-amplifier bipolar stage. Nevertheless, it can be easily compensated with positive feedback or regeneration. A sufficient amount of regeneration can make tuning astonishingly sharp. Another concern is the quality of the detected audio. This, to my knowledge, is subjective. The quality of sound coming out from an earphone can be rated good or fair by two different people. I would suggest that you decide by yourself. So, come on and try the following schematic for the 530 kHz to 1650 kHz AM Broadcasting Band.

A Bipolar Regenerative Receiver Circuit Diagram

Please notice that the 475 pF variable capacitor tunes in the stations whereas the 200 pF variable capacitor controls regeneration. The latter is known as the throttle capacitor. L2 is the tickler coil. In order to regeneration to take place, L1 and L2 must be correctly phased ( very important! ).

The power consumption is very low. The 2N3904 drains some 60 uA from the 9 volt battery and the AC126, about 0.5 mA.As a benchmark, medium powered ( 5 to 10 kw ) local stations within 25 km from my site are heard as fair to loud audio signals.

The audio output stage has no external bias, and doesnt need any. This is because Iceo, the leakage collector current ( about 0.5 mA in my prototype ), is sufficient to build up a usable Beta ( or current amplifying factor ) in the germanium AC126 transistor. This is a bit unusual but it works fine. Also, the signal detection is carried out by the 2N3904 transistor, as it is driven, thanks to regeneration, into its non-linear region. In other words, it works as an amplifier-detector.

Photographs of Ramons Prototype

Using TEA5551T monolithic integrated radio circuit can be designed a AM radio receiver circuit which is designed for use as a portable radio receiver with headphones . 

AM Radio Receiver Circuit diagram

The TEA5551T radio receiver circuit contains all is needed for a AM radio receiver circuit (a complete AM part and dual AF amplifier with low quiescent current).The TEA5551T support a input voltage range (VS) from 1.8 V to 4.5 V but the typical voltage is 3 volts .Because in most case we don’t find to buy inductors you need to build the inductors L1 , L2 , L3 . In the picture bellow you can see the construction data for these three inductors .

Transmitter and receiver circuit using infra red audio signal is applied to emit an audio signal and will received on a headphones. Making his series is not too difficult, the transmitter and receiver circuit scheme can be seen below.

After the series finished, you can try to give the audio inputs on the transmitter and point the LED transmitter to the receiver. Maximum distance is a few meters may not be more than 10 meters, but you can listen to music without wires while using infra red.

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Transmitter and receiver circuit using infra red audio signal is applied to emit an audio signal and will received on a headphones. Making his series is not too difficult, the transmitter and receiver circuit scheme can be seen below.

After the series finished, you can try to give the audio inputs on the transmitter and point the LED transmitter to the receiver. Maximum distance is a few meters may not be more than 10 meters, but you can listen to music without wires while using infra red.

image[link]