DIY Kit TA7358 FM Stereo Integrated Radio Circuit Board 88~108MHz Discrete Parts High Sensitivity AFC

>>This product does not include shell and speakers, and requires external power supply and speakers/earphones to listen. <<

>>This item is a pure frequency modulation (FM) radio kit and cannot be used to receive amplitude modulation (AM) broadcasts. <<

● Digital frequency display
● Pointer signal meter
● Independent mid-amp chip, high sensitivity, can stably listen to many radio stations without connecting the antenna
● Manually controlled squelch (Mute) and automatic frequency control (AFC)
● PLL stereo decoding

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This product has been developed to version 2.XX. Compared with version 1.0, a stereo decoder and an onboard rod antenna have been added. Now it can play stereo programs.

The layout of the components in the new version has changed a lot, which is equivalent to turning the 1.0 version upside down for easier operation. The 2.1X version adds a BNC antenna socket position on the basis of 2.0, and there are minor corrections.

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>>>>>Now updated to version 3.0, with dual panel, TA7335 changed to better TA7358<<<<<

FM7303 V3.0

【Main Features】
1. Receiving frequency: 88~108MHz FM (FM radio frequency band);
2. Stereo demodulation: yes;
3. Power supply voltage: 9~12V;
4. Output power: maximum 2W x 2(8Ω);
5. Board size: 194mm x 96 mm.

【Features】
1. With a dedicated mid-amp chip, high sensitivity, you can listen to many radio stations without pulling out the antenna;
2. It has a digital frequency display, which can directly display the radio frequency and can be used as a debugging instrument;
3. It has a pointer type signal meter, which can be used as a debugging instrument;
4. It has a squelch function (Mute) that is only available in high-end machines. The squelch sensitivity is adjustable and can be manually turned off;
5. With automatic frequency control function (AFC) that can be turned off;
6. The stereo decoder does not need to adjust the separation;
7. Using 2025 dual-channel power amplifier chip, high power and good sound quality.

【Effect】
The sensitivity of this circuit is high, and the finished machine can also listen to many radio stations indoors without connecting the antenna. The sound is relatively stable, and it can receive about 24 FM radio stations (pure noise signals are not counted)

【Version update content】
The update of the v3.0 version compared with the previous version is that it adopts a double-sided panel, TA7335 is changed to TA7358, and the circuit is modified accordingly. The biggest benefit of this modification is the elimination of flying leads, whose function is realized by the top copper foil of the double-sided board.

【Defect statement】
1. Due to the asymmetry of the two sides of the circuit board (especially the single panel), there will be slight natural bending, which has no effect on normal use;
2. Since printed circuit board manufacturers mainly produce multi-layer boards (double-sided and multi-layer boards), they are not familiar with the characteristics of single-sided boards for amateur DIY, and often use single-sided boards as multi-layer boards to make metallized holes for holes. wall treatment. Generally, a single panel does not need metallized hole walls, but if there are metallized hole walls, it is not a fatal error, and it will not have any impact on the normal operation of the circuit, but it requires more welding power when welding components, and the temperature of the soldering iron should be increased;
3. The copper foil of the circuit board and the substrate are bonded by an adhesive, such as long-term, repeated, and repeated welding, the copper foil will fall off;
4. Some organic thin-film variable capacitors have a long inventory time, the shell has a gray layer, and the leads are oxidized.
5. Ordinary grade ceramic capacitors (Y5V, etc.) ceramic capacitors (capacity>300pF) have large errors, the nominal error can reach +80%-20%, and the temperature stability is not good, suitable for filtering, coupling and other requirements. high occasion;
6. If the magnetic core of the intermediate frequency transformer and the frequency discriminator coil is made of porcelain, if the magnetic cap is already at the end of the stroke and still forcibly rotates, the magnetic cap will be broken and the device will be scrapped;
7. At present, the intermediate frequency transformer and frequency discrimination coil are wound by the shop
8. At present, there are more than ten versions of TEA2025 power amplifier integrated circuits (including compatible models). In the case of output short circuit and overvoltage, the 2025 chip is prone to high heat and burns quickly.

For this circuit, the voltage of the signal meter can reach more than 2V, and it can be listened to.
The strong signal station meter indicates that it can reach more than 4V, but it will not exceed 5V. (V1.0)


SC3610 digital frequency display module, it is not only easy to use, but also the debugging process becomes very simple (V1.0)

Squelch switch and AFC switch for manual control, generally only on gear devices (V1.0)

Use 2025 integrated circuit to form a bridge amplifier (BTL), with high power and good sound quality (V1.0)

FM7303型调频收音机电路图 V1.0版(仅供参考)