Keywords: homemade high quality pocket curved frequency stereo radio
Homemade high quality pocket curved frequency stereo radio
It is easy to make performance-based frequency modulated stereo radios with TA2111F. This IC has the advantage that the AFC circuit is integrated in the interior of the IC, no need to be connected to the diode diode, just external 5PF capacitance; FM center frequency part Without the maintenance of the ceramic filter, it will save the intermediate commissioning of the intermediate frequency; the stereo decoding portion does not need to adjust the stereo guided frequency of 19 kHz. It can be seen that it is very simple to assemble the FM radio with TA2111F. So, how is the radio performance of TA2111F? The author has a FM radio radio radio race with TA8127N, compared to the radio assembled with TA2111, and the latter is more, the noise is small, and the stereo light is easily lit. TA2111 is flat package, TA2111 is a double-column-in-in-line package. Figure 1
Circuit diagram of a radio, Figure 2, Figure 3 is a printed panel diagram. Since the unit does not assemble the spreading band, the {7}, {20}, {24} feet of IC, {24} are idle. {16} The foot is a band conversion pin, and the C6 can be turned to the AM band. The FM stereo can be converted to a mono. The machine is input by means of a three-dimensional headset lead in an antenna, the FM signal is input from the TA211F {1} foot input, according to the TA211F pin name, according to the TA211F pin name, can know the signal flow, the audio signal from {13}, {14} foot output is amplified by small power dual-power TDA2822 and pushes the stereo headset. Component Selection: Variable Capacitors Select 4-connected capacitors, where the two-connection capacity of FM is equal to 4 to 24 pf. L1 is from the bollard wire of the ∮ 1mm on the bolton rod around the 3.5 lap. The L2 is covered with a roller wire of the ∮ 4mm with a ∮ 0.7 mm. After L1, L2 is loaded on the board, it is necessary to add a small sponge in the coil and add some molten paraffin on the coil and sponge to prevent the occurrence of motor vibration. The L4 is wrapped around the 5 lap on a round bar of ∮4.5 mm with a 0.7 mm. L3 is an FM sympathy. The potentiometer uses a micro-donor potentiometer. Debug: The assembly is completed, the power supply, the large volume, and the rotary variable capacitor can receive several radio broadcasts, indicating that the installation is correct. Then follow the following steps. 1. Adjust the radio frequency reception range to 88 ~ 108MHz, first turn the variable capacitance smoothly to the bottom, mobilize the oscillation of the fine-tuning capacitor, allow the radio to receive a radio station of about 108MHz; then turn the variable capacitance counterclock to the bottom Use the teeth slick the moving coil L2, change the hut distance of the coil, so that the radio receives a radio of about 88 MHz. This repeatedly adjusted several times until the radio received a radio near 88MHz and 108MHz. 2. Adverse low-end sensitivity: first turn the variable capacitance to 106MHz, rotate the antenna of the fine-tuning capacitor with a screwdriver until the sistead of the sisena in the speaker is the greatest; then the variable capacitance is rotated to 92MHz, and the mobile coil L1 is used. Change the inter-turn distance of the coil until the sake of the sishan of the speaker is the greatest, so repeated several times. 3. Taxi adjustment: Tune the magnetic cap of L3 with a screwdriver, so that the sake of Shasha in the speaker is the smallest.
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