[Gllug] 2.6.31 is out

[Peter Corlett]

On 14 Sep 2009, at 23:59, Geo wrote:
[...]
>> Commercial units are probably as rare as hen's teeth now, but they're
>> also really simple and suitable for a first electronics project.
>> (Especially as there's about a fiver's worth of parts in it, tops,  
>> and
>> they seem to sell for ten times that.)
> do you have aURL for the design etc of one of these units by any  
> chance?
> thanks

No, but they're so simple you don't need a schematic. You attach a bi- 
colour LED and suitable drop-resistor (1K should be about right)  
between signal and ground on all of the serial lines you are  
interested in.

A bi-colour LED is basically a red and green LED inside the same  
package, connected so that it glows red if the current flows in one  
way, and green if it flows the other. Since RS232 uses a positive  
voltage for 0 and a negative voltage for 1, the LED colour (or lack  
thereof) indicates the state of the line.


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