FM/AM Radio Kit, DIY

The CF210SP kit is a dual-band radio receiver, capable of receiving both FM and AM stations, ideal for electronics enthusiasts and students who want to learn through practice how a complete radio receiver works. The kit is delivered with all the components necessary for assembly and includes a printed circuit board (PCB), on which the values and positions of each component are clearly marked.

The FM section is built around the CD9088 integrated circuit, mounted in an SMD package, which ensures stable reception in the 76-108 MHz band with the help of an internal 70 kHz PLL system and an AFC circuit (automatic frequency control). Tuning is done manually via the double variable capacitor CBM-444 and coil L2, allowing precise adjustment of the desired frequency.

The AM section uses the TA7642 integrated circuit in a TO-92 package, a compact amplifier-detector with 10 internal transistors, covering the 525-1605 kHz band with the help of the ferrite rod and the dedicated coil. Both sections send the audio signal to the power amplifier TDA2822, which delivers clear and powerful sound to the 40 mm speaker included in the kit.

The kit also includes a 3.5 mm headphone jack, a power indicator LED, a 10 KΩ volume potentiometer, and a DPDT switch for FM/AM band selection. The kit is standalone, requiring no Arduino, STM32, or ESP32 development board, operating completely independently powered by 2 AA batteries.

Specifications:

FM Band: 76-108 MHz

AM Band: 525-1605 kHz

FM Circuit: CD9088 (SMD, 70 kHz PLL, integrated AFC)

AM Circuit: TA7642 (TO-92, 10 internal transistors)

Audio Amplifier: TDA2822

Power Supply Voltage: 3V (2 x 1.5V AA batteries)

Minimum Operating Voltage: 1.8V

Included Speaker: Φ40 mm

Headphone Jack: 3.5 mm stereo

Volume Potentiometer: 10 KΩ

Band Switch: DPDT, 3 mm handle

Variable Capacitor: CBM-444 (double)

FM Coil (L2): 8T5

FM Coil (L1): 7T5

AM Ferrite Rod: 3 x 8 x 40 mm

Total Number of Components: 56 positions

Mounting Type: THT + SMD (mixed)

Power Supply: 2 x AA (batteries not included)

Usage:

Identify all the components from the kit and sort them by value before starting assembly.

Mount the resistors first, vertically or horizontally depending on the hole spacing, according to the markings on the PCB.

Mount the ceramic capacitors, respecting the values indicated on the board.

Mount the electrolytic capacitors respecting polarity: the white terminal on the PCB indicates negative (-).

Solder the CD9088 integrated circuit (SMD) carefully, aligning the pins with the copper tracks before soldering.

Mount the TA7642 and TDA2822 in DIP packages, respecting the orientation marked on the PCB.

Solder coil L2 (8T5) last among all components, to facilitate later adjustment of the FM band coverage.

Connect the speaker, antenna, headphone jack, LED, and potentiometer according to the SP, ANT, J, LED, and VOL markings on the PCB.

Insert 2 AA batteries and switch to the FM band.

Fine-tune coil L2: increase the distance between turns for high frequencies (108 MHz), reduce the distance for low frequencies (76 MHz), until full band coverage is achieved.

Switch to the AM band and adjust the coil position on the ferrite rod for optimal reception.

After tuning, assemble the case and secure all elements with the screws included in the kit.