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Digidock FM Transmitters
Peripherals | First Looks
Fri 28 Jul 2006

Small Radio Wonder


The AC-2112 is a simple FM Transmitter that also charges and provides power to iPod concurrently.

Packing two additional functions is the AC-2220 with a fully functional USB port and MP3 support.

Simply load a thumbdrive with MP3 music and pair it with the AC-2220 for instant playback.

As the world continues to be swept off its feet by the iPod fever, arguments about the ongoing fad are largely divided between the pros and the cons. While the con of iPods being overtly ubiquitous is fairly obvious (thereby causing iPods to lack character), there are, thankfully, more pros than cons brought about by the world's most recognizable multimedia gadget. Apart from spawning a huge galore of aftermarket accessories for which consumers can purchase to style their iPods as they see fit, the iconic player has also triggered accessory manufacturers in rolling out a new ecosystem of supplementary products to glorify the whole experience of owning an iPod. One such product is the Digidock series of FM Transmitters.

Reason to Exist

Granted there is a growing number of automobile magazines judging cars based on whether or not they are iPod-ready out of the factory doors, the rationale of creating accessories specially targeted at those who embrace the phenomenon requires no further explanation. It's only in recent times that car audio manufacturers have been rolling out head units equipped with a 3.5mm audio-in jack, but what about the rest of the driving population? This is where devices like the Digidock FM Transmitter come into play with an infinitely huge market potential. Affordable and easy to install, it offers car owners a quick option to breathe new life to their existing audio head units that lack an audio-in jack to port digital music from external audio players. With this gadget, car owners no longer have to burn selected digital music into CD compilations (for older head units that do not read MP3 CDs) or burn and monitor numerous MP3 CDs as the collection escalates.

Riding The Waves

Like many wireless devices these days, the Digidock FM Transmitter is engineered to utilize radio waves as the wireless transmission medium for data packets. The working principle is essentially a highly simplified version of broadcasting audio signals, but unlike your local broadcast stations that are capable of reaching a huge number of recipients, the Digidock FM Transmitter is only powerful enough to transmit radio waves within a short radius for clear reception; case in point is the head unit within your car.

Breezy Installation

Being a crudely simple device, installation of the Digidock FM Transmitter is a fairly simple affair. Even without looking at the instruction sheet, one should be able to identify the various critical connectors to instinctively install the transmitter, pair it with a portable audio player and start enjoying digital music. Just about the only hurdle that users might face is the tuning of the car's head unit to the frequency range of the Digidock FM Transmitter. Considering that most users would have already tuned all the available stations shortly after collecting their car or installation of the head unit, the challenge then is not so much the installation of the transmitter but rather recollecting the steps involved in tuning radio frequencies of the head unit.

FM Transmitters from Digidock are broadly categorized into 2 groups: Pure FM Transmitter and FM Transmitter with data playback from USB storage devices. Units in both categories are based upon the same platform with the former ideal for users who already own high capacity portable audio players while the latter is more suited for those without digital music players but yet want to enjoy the convenience and variety of digital music when on the road. Representing the former group is the US$40, AC-2112, a simple FM Transmitter that also doubles up as an iPod charger. More interesting is the US$58, AC-2220 which packs the additional functionality of playing MP3 files from USB storage devices such as thumb drives. Navigation of tracks is facilitated by a very basic set of play/pause, forward, and back buttons. Being a basic device, alternate playback modes such as shuffle and repeat are unfortunately unavailable.

Test and Conclusion

Put to the test, due to the bandwidth of radio waves and the lack of any form of amplification and signal processing circuitry, both versions of Digidock FM Transmitters could only deliver flat, uninspiring, and audibly sub radio broadcast quality audio. Nevertheless, considering its convenient bridging functionality for old car head units with modern digital audio and that it does work as easily as advertised while being more affordable than expensive car kits, it's still worth checking out the Digidock FM Transmitters.


Product Specifications


  • FM Channels: 88.5 / 88.7 / 88.9 / 107.5 / 107.7 / 107.9 MHz
  • Operation Temperature: 0 - 60 deg. Celsius
  • Storage Temperature: -10 - 70 deg. Celsius 
  • Power Input: DC+12V
  • USB Output: +5V / 700mA (max.)
  • Dimensions: 40 x 146 x 23 mm (W x H x D)
  • Weight: 65g

   AC-2220 (with USB storage playback support)

  • Supports MP3 format
  • Supported Bitrate: 32Kbps - 32Kbps
  • Format: FAT16 / FAT32
  • USB: 1.1
  • FM Channels: 88.5 / 88.7 / 88.9 / 107.5 / 107.7 / 107.9 MHz
  • Operation Temperature: 0 - 60 deg. Celsius
  • Storage Temperature: -10 - 70 deg. Celsius
  • Power Input: DC+12V
  • USB Output: +5V / 700mA (max.)
  • Dimensions: 40 x 147 x 26 mm (W x H x D)
  • Weight: 75g