[time-nuts] Slightly OT: inexpensive USB analog-digital converter?

[John Ackermann N8UR]

Hal Murray wrote:
>> (My goal is to add digital voltage and current monitoring to some
>> older bench power supplies.) 
> 
> Measuring voltage is simple.  If the input range is too big, you need a few 
> resistors.  If it's small, you lose a few bits from the top of the A/D.  Add 
> an op-amp if you need them.
> 
> Measuring current gets tricky.

Fortunately the power supplies in question already have analog voltage 
and current metering, so I should be able to just tap into the existing 
shunt resistors, though I may need to do some calibration and scaling.

John