Summary of Build an Arduino-Controlled AM/FM/SW Radio
This article details the construction of a multiband radio by integrating the Si4844-A10 analog receiver chip with an Arduino microcontroller. The project supports AM, FM, and Shortwave bands using minimal support components. Key challenges include soldering the SSOP-24 chip, potentially using a carrier board for easier handling, and selecting appropriate antennas and tuning potentiometers. The design relies on 3.3V logic and includes audio output via external amplified speakers.
Parts used in the Arduino-Controlled Multiband Radio:
- Silicon Labs Si4844-A10 receiver chip
- Arduino microprocessor
- Reclaimed ferrite loop antenna (for AM)
- Reclaimed telescopic antenna (for SW/AM)
- Amplifier Q1
- Variable resistor VR1 (linear potentiometer)
- Economical amplified speakers
- SSOP-28 carrier board
- Fine point soldering tip
- Solder braid
- Surface mount ferrite beads
- Surface mount capacitors
The idea of a single chip radio is intriguing. The prospect is especially interesting to me because, frankly, I envy the analog skills I associate with building a radio receiver. When I browsed the circuit literature in the area, I came across the Silicon Labs collection. One of their chips, the Si4844-A10 caught my attention. This receiver has AM/FM/SW capability with all the bells and whistles and it is designed to work with a microprocessor. Best of all, the support components required are mainly associated with the microprocessor display and control functions with only a small amount of antenna support needed. I couldn’t resist taking the plunge.
Reference Documents
Familiarity with the chip’s data and application information is strongly encouraged. The three documents linked below are highly recommended for understanding and building the project:
The Basic Circuit
Figure 1 presents the basic circuit for the receiver and the schematic is adapted from the Silicon Labs Si4844 datasheet and application notes. I used a reclaimed ferrite loop from a discarded portable AM/FM radio as the required AM antenna. I think that a higher quality and larger ferrite would be an improvement. Q1 is the amplifier for the SW/AM and I also used a reclaimed telescopic antenna in that section. It is notable that the design guide, linked above, gives several alternatives and different approaches for the antenna components.
The variable resistor (VR1) is a critical component since this will be used to adjust the receiver frequency – the tuning knob. It is recommended that a good quality linear potentiometer be used. For the audio out, I chose to use a set of “economical” amplified speakers that I had from a retired desktop PC. Certainly, a simple stereo amplifier could also be used. Everything on the board is 3.3v and all GNDs are connected.
The most difficult part of the construction is probably working with the chip’s SSOP-24 form factor. If you don’t have the experience and equipment to use SMT ICs, the use of a carrier board may be the easiest way to accomplish the task. I had an SSOP-28 carrier board and with a fine point soldering tip and a lot of patience (and some solder braid to undo bridges); I was able to mount the chip so that it could be accessed as a DIL package. The other potentially difficult components to work with are the couple of surface mount ferrite beads and capacitors. These components can also be hand soldered onto a carrier board and treated like a DIL package.
Read more: Build an Arduino-Controlled AM/FM/SW Radio
- What capabilities does the Si4844-A10 chip offer?
The receiver has AM/FM/SW capability with all necessary features designed to work with a microprocessor. - How can I improve the AM antenna performance?
Using a higher quality and larger ferrite is recommended as an improvement over the reclaimed one used in this project. - What type of potentiometer should be used for tuning?
A good quality linear potentiometer is recommended for the variable resistor used to adjust the receiver frequency. - Can I use a different amplifier for the audio output?
Yes, a simple stereo amplifier could also be used instead of the economical amplified speakers from a retired desktop PC. - Is it difficult to work with the Si4844-A10 chip form factor?
The SSOP-24 form factor is considered the most difficult part of the construction if you lack experience with SMT ICs. - What is the easiest way to handle the SSOP-24 chip without SMT equipment?
Using a carrier board allows the chip to be mounted so it can be accessed as a DIL package. - What voltage level is used for everything on the board?
Everything on the board operates at 3.3v and all GNDs are connected. - Where can I find detailed information about the chip?
Familiarity with the datasheet, programming guide, and design guide provided by Silicon Labs is strongly encouraged.
