logic analyzers under USD $500

Phil Endecott spam_from_qihw at chezphil.org
Sat Nov 5 12:42:08 EDT 2011

Ron K. Jeffries wrote:
> A friend uses this USD $389 logic analyizer from Intronix in his lab. How
> do the specs look?
> https://www.pctestinstruments.com/logicport/specifications.htm

When I needed a logic analyser I ended up buying a Rigol DS1102CD.  It 
has 2 100 Mhz scope channels and 16 logic channels.  Having both 
analogue and digital channels has definitely been useful.  On the other 
hand, it lacks an external clock mode.

I considered various PC-connected devices.  The main disadvantage was 
that I would need to also buy a Windows computer to operate them, and 
that would push the cost above the Rigol.  (And I'd need a bigger 
desk.)  At that time, the specs weren't as good as the Intronix device 
that you've linked to.

One feature of the expensive Tektronix analysers is that the signal 
wires are actually coaxial, and you can have a pair of clips for each 
signal if you want.  You need to think about how you would connect the 
Intronix box to your device under test, and how long the signal/ground 
loops would be.  Unlike a scope with X10 or X100 probes, the noise you 
pick up is injected into the circuit as well as into the analyser.  
Whether this matters depends on the speed of the signals you're looking 
at.  I found the Rigol was just about OK for a 120 MHz bus.  For things 
like I2C at normal speeds there shouldn't be any problems.

If you really only want to do I2C, I'm sure that there must be much 
simpler and cheaper devices that would work just as well.  I would 
probably try to make my own...

Regards,  Phil.

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