bar code reader

[granddad]

ryteker
SFH7741 is an interesting device, I was trying a similar bar code design and had problems with ambient light , it was picking up 50Hz from my work desk lamp ! then I got into another project ( happens a lot ) , I might get a SFH7741 and revisit only 1£ from Farnell . Take a look at manchester encoding for the barcode design.

NFC sameish as RFID , I would think a bit expensive.

 

[ryteker]

Granddad,
I'll take a look at the manchester coding/

 

[dougy83]

NFC sameish as RFID , I would think a bit expensive.

RFID tags are available for <$0.30 ea. The reader module is available for <$4. ref
**broken link removed**
**broken link removed**
The linked reader modules are configured for SPI communications, and you can have multiple readers connected to a single main controller (e.g. microcontroller or PC).
The linked tags can be split into two parts; the circular insert has the RFID chip and coil on it. You could just use the circular insert if you needed the tag to be smaller.

 

[ryteker]

Thanks Dougy83.
I have some RFID readers and tags (MicroChip type used in animal 'chipping') and I also have several 40 mm square readers, which seem to work very well.
I also have a couple of the readers and 10 tags that you suggest in your ebay links, but have not found them particularly reliable probably due the the distance from the reader to the tag (which is around 20 mm), and really wanted to come up with something that was very cost effective and small.
I have just ordered a 'AMS TSL250R-LF PHOTODIODE' that converts 'light' into voltage, and by using red,green or amber leds as color enhancers, may be able to detect 'coloured' bars ... I have read something about it somewhere on the 'net so thought I'd give it a try.
I think I may have come up with a possible alternative to pure Bar code reading, but still 'thinking it through' and want to experiment with it before I am convinced it would be worth pursuing.
I'll keep the thread updated with my findings as I progress (or not !!!!)

 

[dougy83]

I also have a couple of the readers and 10 tags that you suggest in your ebay links, but have not found them particularly reliable probably due the the distance from the reader to the tag (which is around 20 mm), and really wanted to come up with something that was very cost effective and small.

What frequency were the tags? The low frequency have a shorter range (but less affected by metal/water), while the higher-frequency ones have greater range albeit being more picky about close metal/liquid.

The coloured sensor sounds interesting.

 

[ryteker]

To be honest I can't remember, I'd have to check them out again later.
Like lots of other 'hobby' based things, it gets 'interrupted' by 'Work' so only have a limited time to 'play' at the moment .... even though I am retired, I still get 'roped in' to projects.

 

[granddad]

Lateral thinking .... no tags no sensors.... any environment ... there you go....
http://www.voja.rs/PROJECTS/ocr/ocr_0.htm

 

[ryteker]

Yes ... looks good ... for a one off .... but for around 100 .. Hmm .... these units are also acting as Loco detection units as well as Loco ID's for tacking etc. ... this for when we automate the whole layout ....