FM Stereo Integrated Radio Circuit Board Assembly Kit Electronic DIY Discrete Parts High Sensitivity
Model 1: Finished circuit board version 3.0 (no shell speaker)
Model 2: 3.0r1 version of the circuit board parts (no shell speaker)
Model 3: 3.0r2 version of the circuit board parts (no shell speaker)
>>This product is a spare part for assembling the circuit board of an FM radio, not a finished product.
<<>>This product is a circuit board kit, without housing and speakers, you need an external power supply and speakers/headphones to listen.
<<>>This product is a pure frequency modulation (FM) radio kit and cannot be used to receive amplitude modulation (AM) broadcasts.
<< ● Digital frequency display ● Analog signal meter ● Independent mid-amp chip, high sensitivity, stable listening to many radio stations in big cities without antenna connection ● Manually controlled mute (Mute) and automatic frequency control (AFC) ● Phase-locked loop Stereo decoding >>
This product has complete functions and strong controllability. It is not comparable to a second-hand radio and cassette recorder. It is even more incomparable with an FM receiver circuit built with several transistors.
<<>>Our shop can provide debugging services for the FM7303 FM radio kit. Friends who have not installed the machine can send the welded complete circuit board back to our shop for debugging. The debugging fee is 50 yuan. If no components are missing, damaged, or a large number of manufacturing errors, the commissioning fee can be waived.
<< ************************************************** ************************************************ This product has been developed to version 2.XX. Compared with version 1.0, a stereo decoder and on-board whip antenna have been added, and stereo programs can now be played. The component layout of the new version has changed a lot, which is equivalent to turning the 1.0 version upside down for easy operation. The 2.1X version adds a BNC antenna socket location on the basis of 2.0, with a small amount of amendments. ************************************************** ************************************************
>>>>>It has been updated to version 3.0, with dual panels, TA7335 is changed to a better TA7358<<<<< FM7303 type FM radio kit uses three Toshiba dedicated chips to form the receiving part: TA7335P is a classic FM front-end chip, which is widely used in many radio and receiver products at home and abroad. TA7303P is a dedicated FM mid-amplifier and frequency discrimination chip. Many famous models of SHARP radios, such as GF-777z, GF-515z, GF-6060X, GF-9191X, etc., are used in many car radios. It can also be found. TA7061BP is a dedicated mid-amp chip, and there is no application case for radio cassette recorders and radios. TA7343AP is a phase-locked loop stereo decoder.
The combination of these four chips and 2025 power amplifier into a simple circuit can provide higher receiving performance, suitable for amateur radio enthusiasts, can also be used as an entry-level FM DX equipment. [Product name] FM7303 integrated circuit FM radio experiment board assembly kit v2.0/2.16
[Main features]
1. Receiving frequency: 88~108MHz FM (frequency modulation broadcast frequency band); 2. Stereo demodulation: Yes;
3. Supply voltage: 9~12V;
4. Output power: maximum 2W x 2(8Ω);
5 . Circuit board size: 194mm x 96 mm.
[Features]
1. It has a dedicated mid-amp chip, high sensitivity, and 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, which can be used as a debugging instrument;
3. It has an analog signal meter for use It can be used as a debugging instrument;
4. It has the muting function (Mute) only available in high-end machines, the muting sensitivity is adjustable and can be turned off manually;
5. It has the automatic frequency control function (AFC) that can be turned off;
6. The stereo decoder does not need to adjust the degree of separation;
7. Using 2025 dual-channel power amplifier chip, high power and good sound quality. [Package content]
[Commodity description]
1. The circuit of this kit is assembled according to the official chip data manual and some classic cases. Practice has proved that it has the advantages of easy production and easy debugging, and the effect is far better than simple discrete circuits;
2. The manual contains circuit schematics. And circuit board diagrams, as well as debugging methods and experience under amateur conditions. If you need more information and professional debugging methods, please download or refer to the relevant books on the Internet;
3. TA7335P, TA7303P and TA7343AP have a long history. There is no original brand-new source, and the basic products that can be obtained are disassembled products or stocks for many years, with older colors, and oxidation of wax and stitches. The price of the disassembled products of these three types of chips sold online is not low, and a small amount of them are damaged. The three types of chips issued by our shop have been tested with IC sockets, and the unusable waste products are screened out to ensure normal functions. Except for the three-type chip, the other components in the kit are all brand new. If you do not accept the disassembly chip, please do not shoot;
4. As the supply of TA7335P, TA7303P and TA7343AP chips is small, our shop may replace them with compatible models, such as CD7335, KIA6003S, KIA6043S, etc.;
5. High stability requirements Capacitors such as resonant capacitors are equipped with expensive mica capacitors or NPO series ceramic capacitors. The remaining capacitors with small capacitance are ceramic capacitors or film capacitors, and the large-capacity capacitors (μF level) are electrolytic capacitors;
6. The variable capacitor uses CBM443DF FM quadruple variable capacitors, and only the FM connection is used;
7. Circuit board The base is made of glass fiber material, the thickness measured is about 1.5~1.6mm, the single-sided green/butter white lettering, the pad is sprayed with tin, and it can be welded directly without grinding;
8. There may be some scratches on the base surface and copper foil surface. As well as dust, and traces of washing the board;
9. The circuit board obtained by the buyer may be slightly different from the sample in the picture, mainly due to the change of component position and the same circuit structure. This product has been modified and perfected n times from trial-produced samples to products sold (mainly to modify the wiring of the circuit board), and is still in continuous improvement. Usually minor insubstantial modifications, such as slight movement of components and minor wiring adjustments will not change the version number, and will not re-photograph and upload, hereby declare.
[Graphic Description]
A sample of the produced circuit board. Among them, the TA7335P and TA7303P ICs have long been discontinued, and the kit provides the normal disassembly parts for testing. (V1.0)
FM7303 V1.0()
[Effects of use] The circuit has high sensitivity, and the finished machine can listen to many radio stations indoors in Wuhan without an antenna. The sound is relatively stable. It can receive about 24 FM radio stations (not counting pure noise signals), compared with some The low-cost radio has good reception of weak signals, and the noise is not obvious, which can better meet the listening requirements.
[Version update content] v3.0 version is updated compared to the previous version: adopting a double panel, TA7335 is changed to TA7358, and the circuit has been modified accordingly. The biggest benefit of this modification is that it eliminates flying leads, and its function is realized by the top copper foil of the double-sided board.
[Correction Description] [Defect statement]
1. Because the two sides of the circuit board are asymmetrical (especially single-sided), there will be slight natural bending, which has no effect on normal use;
2. Because the printed circuit board manufacturers produce multi-layer boards (double-sided and double-sided) Multi-layer boards are the main ones, but they are not familiar with the characteristics of single-sided boards for amateur DIY. They often treat single-sided boards as multi-layer boards to metalize the holes. Generally, the single-sided board does not need to be metalized, but if there is a metalized hole wall, it is not a fatal error and will not cause any impact on the normal operation of the circuit. It is just that when soldering components, more soldering power is required, and the soldering iron temperature should be increased;
3. The copper foil of the circuit board and the board base are bonded by an adhesive, such as long-term, repeated, and repeated soldering will cause the copper foil to fall off;
4. Some of the machine-film variable capacitors have been in stock for a long time. There is a gray layer, the lead is oxidized, just do a little treatment, and it will not affect the use;
5. Ordinary ceramic chip capacitors (Y5V, etc.) ceramic chip capacitors (capacity>300pF) have a large error, and the nominal error can reach +80%- 20%, temperature stability is not good, suitable for occasions with low requirements such as filtering and coupling;
6. The magnetic core of the intermediate frequency transformer and frequency discrimination coil is made of porcelain. If the magnetic cap is already at the end of the stroke, it will cause the magnetic The cap is broken, causing the device to be scrapped;
7. At present, the intermediate frequency transformer and frequency discrimination coil are self-winding by the shop, and the appearance is not as beautiful as the factory product;
8. At present, there are more than ten versions of TEA2025 power amplifier integrated circuits (including compatible models). They are all domestic products. In the case of output short circuit or overvoltage, the 2025 chip is prone to high heat and burns quickly. [Notes] 1. ; 2. ; [Q&A] Q: How to prove that the sensitivity of integrated circuit FM radio is higher than that of general transistor FM radio? A: Listen to the noise without radio frequency. Large noise means high sensitivity, otherwise it will be low. The noise of an FM radio without a station frequency is determined by its working principle and will inevitably be generated. It cannot be solved with an excellent circuit (the squelch is just turning off the output). Transistor FM radios are expensive. The number of intermediate amplifier stages is generally only 2 to 3, and the gain is very limited. Therefore, the noise at no station is much smaller than that of integrated circuits, which is very "clean". Those who don't know think this is the advantage of discrete circuits. In fact, this is precisely its shortcoming.
Our shop also made a discrete FM receiving circuit, which proves that if the discrete circuit is not very complicated, its sensitivity, selectivity and distortion must be far inferior to that of integrated circuits. It’s okay to play around, and it’s not necessary to pursue high indicators.
[Others]
1. If the buyer cannot debug this circuit well, he can send the soldered circuit board to our shop for a commissioning fee of 50 yuan. If the welding is good, the assembly is error-free, and the components are intact and undamaged, the commissioning fee is free, and the player pays the round-trip freight. Remember to note that the board sent must be complete and not missing pieces.
2. Regarding the principle and assembly technology of the radio, it is recommended to visit the crystal radio forum www.crystalradio.com, where there is a vast space for communication.