The particular RC car transmitter we're looking at is a Spektrum DX4C. These radios are typically used to control hobbyist level RC cars, boats and occasionally robots! Spektrum is a part of Horizon Hobby, one of the largest hobby product distributors in the country. The radio in this teardown operates in the 2.4GHz band using a spread spectrum protocol called DSM.
Spektrum DX4C RC Radio
Opening up the radio reviews a fair amount of wiring and various circuit boards through the radio.
The Insides of the DX4C
There are several minor circuit boards inside of the Spektrum radio that contain primarily switches. These small boards appear to be hand soldered.
One of the small switch PCB's
In addition to the switch boards, there are also a small PCB for an SD card; all that resides on this board is an SD card socket and a single capacitor.
The SD Card Board
The microcontroller of the radio
On the primary circuit board of the Spektrum radio, there is a PIC microcontroller. The radio uses a PIC18F66J16 in a 64 pin TQFP package to run the COG (Chip On Glass) display; the analog and digital inputs, and the communicate with the radio module. In addition to the microcontroller, there are a handful of connectors, an oscillator, a speaker, and a handful of caps.
The main PCB of the DX4C
The U1 component is a 3.3v linear regulator
The Spektrum radio runs off of 4 AA sized batteries. The voltage from the batteries then enters a 3.3v linear regulator in an SOT-223 package located on the rear of the main circuit board.
The RF module installed on the main PCB
The RF module is heart of this radio transmitter. Horizon Hobbies (owner of Spektrum Radios) created a RF module that is FCC certified that is then placed in multiple products. The radio module has a uFL connector, a male header, and a metal shield.
The RF module
The metal shield was then removed so more details about the electronics could be obtained. The shield was removed to reveal quite a few components inside the module.
The RF module with the shield removed
There are two primary components inside of this RF module. The first is a Cypress CY8C21434-24LTXI system on a chip in a 32 pin exposed pad package. The second major component is a Cypress CYRF6936-40LTXC 2.4GHz transceiver in a 40 pin exposed pad package. The two components communicate with each other over an SPI interface.
This tear down covers most of the electronics that are found in the radio, as you can see there aren't a lot of components inside of this radio. Additionally, a lot of the components and small circuit boards are modular, allowing them to be used in other products in the Spektrum product line. The FCC information about this radio can be found here and more information about its radio communication protocol can be found here.
Thanks for looking at this week's Teardown Tuesday. Stop by next Tuesday for another teardown!
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