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Chaoyu CY-668A and ES-2008 Wireless FM Transmitters

This is an interesting device to freak around with.

We were once used to Western and Japanese manufacturers smearing their branding all over products, now we're getting used to Chinese manufacturers doing their darnedest trying to hide their identity. Anyway, I can reveal that the company behind this is ChaoYu Electronics Technology from the Guangdong Chenzhen region.

Just to make model identification even harder, there are two ChaoYu devices which are seemingly exactly the same, they go under the model numbers CY-668A and ES-2008. The only difference seems to be the sticker displayed on the battery compartment cover as shown below. The battery cover of the ES-2008 also includes a serial number which the CY-668 does not display anywhere on the device.

There are also others with the model number 668A but which have 'MUSIC' instead of 'ChaoYu' displayed on the LCD screen. Apart from not having a torch, these are probably best avoided as the display is poor when looked straight on.

 

Battery coversThe first one I bought came directly from China, it took the best part of a month to arrive. Usual deal, £2 for the product and £8 for the post and packaging. This first one lasted less than an hour before it packed up. Either this points to my bad luck or an infant mortality issue with some of these products. I suppose we really cant expect the manufacturers to soak test them for 24 hours given the cost. This one had a proper blister pack and instructions in nearly readable English.

The replacement came from Manchester from a Chinese sounding vendor operating out of his flat. Again about £2 for the product and £8 P&P. This time it took 8 days to arrive and was sufficiently packed but very much hand packed. It was just taped up in bubble wrap, no branding or retail packaging at all.

Another came from China but had no blister pack, no instructions, no torch and a poor display.

Quality of delivery, in conclusion is variable depending on how your product is sourced.

Here's what you get.

The Transmitter
Usually comes with a black or white body but there are other escutcheon colours seen from time to time. The unit is a stereo PLL controlled device with dedicated LCD display which shows output frequency among other things.

It has a flying 3.5mm jack lead which takes its audio from the headphone socket of your MP3, minidisk, Discman or cassette walkman if you're feeling really retro.
It has three frequency memories so you can assign each of the three memories a frequency value for quick access. Frequency coverage is the full 87.5 - 108MHz in 100kHz increments giving a total of 205 possible frequencies.

The frequency memories are often described as being non volatile, but in practice, the device will default the the three factory values in the table below if either the battery or external power source is not available for more than a fraction of a second.

Memory Frequency (MHz)
CY-668A with torch CY-668A with 'MUSIC' on screen
M1 87.5 87.5
M2 102.0 98.0
M3 108.0 108.0

 

Power

Power comes from either 2 internal AAA batteries or from a mini USB socket.
A cigar lighter adaptor which drops voltage down to 5v is usually supplied, along with a USB lead. The USB cabling of course, does not carry data, only power but it does make it easy to use with your computer as power can be obtained from your USB root hub. The device charges the internal batteries in situ and around 3.25V is seen on the battery terminals when the device is powered via the USB socket.

Unlike the Belkin, this device has a power switch. There are in fact three power states. Transmit, standby and off. When off, there is no LCD display and the torch is disabled. It puts the microcontroller to sleep, leaving only the clock running in the background. There is no mention of the off state in the instructions.

Amazingly, this little device has a little switch mode supply tucked away inside it [Technical Discription]

Knobs and Whistles

It also has three other features just so it can take the total piss.
A built in torch on some versions, just press the up and down buttons at the same time and the white high brightness LED stays on indefinitely until you perform the same action to cancel it.
A built in clock (this will need to be reset if both power sources are removed)
A digital thermometer. The PA device has no chance of overheating at this power level but in any case, it's at the opposite corner of the board to measure this. It just measures ambient temperature in degrees F or Centigrade alternately, probably elevated very slightly by being in proximity with the solid state power switch and voltage dropping diodes.

Range and performance :-

Well it actually doesn't sound really that bad at all. It seems like there's no real limiting and it gets really nasty if driven too hard but if it's driven sensibly with a suitably normalised digital audio source it works OK. I'd recommend driving it via the Winamp Sound Solution plug-in for best results.

It reaches easily all the radios in my house, fully quietening and full stereo. I wandered down the road with a portable on a carefully selected frequency it had my mono portable dropping out after approx 30/50m.

Given that the signal lead acts as its antenna and is only 200mm in length, it's got to be really inefficient for a frequency of 3m wavelength. The simple addition of a simple extension male to female jack lead may help here and will presumably be within technical compliance. 

Frequency stability is very good. I measure an typical error of less than 2kHz error which is very acceptable given the wide deviation found in FM audio broadcast systems.
 

       
   
       
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