Saturday 4 January 2020

The Swift Micro Caller

Graham Fell of Kendal Swifts has discovered some amazing new technology: an MP3 player costing less than £1. 

Together, and with others, we have been trialling it and so far we believe that it is a viable, very low cost solution. There are many vendors selling this piece of kit; try googling "TF card U disk MP3 Format decoder". It comes as a printed circuit board, there is no housing, you need to supply your own.
You can plug calls in on a USB memory stick to the U disk port, or on a Micro SD card into the TF card port. The tweeter should be connected to the 3W Speaker port. The system is powered with a Micro USB cable compatible with a mobile phone or Kindle charger (not iPhone).

Our analysis so far:
1. Volume is not quite as loud as Cheng Sheng/Kinter type systems at maximum volume, but it is loud enough for most situations. Usually one turns the volume down on these other systems.
2. Sound quality is good, with no distortion at maximum volume.
3. Control buttons not as convenient as control knobs, but not difficult to use.
4. There is only one speaker port (2 on a Cheng Sheng). We have not tried connecting 2 tweeters in parallel to this port.
5. We don't know yet what the Swifts might think of it [Update: we have attracted Swifts into boxes.]
6. It seems to consume a very low amperage, so we are testing to see whether it is feasible to run for a whole season on a single battery charge, without solar panel.

For a complete system, you need:

The TF card
USB memory stick or Micro SD card with calls in MP3 format
Micro USB cable (£1 from Pound shop)
USB mains plug 
Tweeter and speaker cable

You can probably buy all this for  less than £10

And you need a 240 volt timer. We recommend a digital timer as it does not need resetting after a power outage.

As an interim we have made some housings on a laser cutter. as in the following pictures. For this illustration we have a short speaker cable, you may well need 6 metres or more:

Micro Caller with Micro SD card
Micro Caller with USB memory stick
With power on and a USB memory stick or MicroSD card inserted, the Micro caller will start to play, cycling indefinitely through all the tracks.
To increase volume: continuously depress the Next/V++ button
To decrease volume: continuously depress the Prev/V-- button
To move to the next track: short press on Next/V++ button
To move to the start of the current track: short press on Prev/V-- button
To stay on the current track: press Repeat
To revert to cycling through all tracks: power off and then power on again.

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