Nice job !
But let me explain that your protection diodes aren't effective for current overrun on sensing resistances. As you said, the voltage drop on forward current of the diode is around 1V maybe a bit less . let's say 500mV. At 500mV, the resistance will dissipate (U^2/R) (0.5)^2/0.05 = 5 W. At 1V, the power dissipated at resistance is 20W! So the resistance will burn even if the diodes are closed, because maximum power rating of the resistance is 1W. To have 500mV at the resistance, current flow will be 10A. Diodes are only 3A . The protection will be effective only for non repetitive small spikes, but rather more to protect your phidgets. Arnaud _____ From: Jeff Berkowitz [mailto:[email protected]] Sent: dimanche 28 octobre 2012 02:42 To: [email protected] Subject: [Vo]:Home made data logging ammeter Hi all, I built this USB-connected ammeter so we could log current flow accurately and rapidly while doing electrolysis and also electroplating. http://pdxlenr.blogspot.com/2012/10/a-pretty-good-data-logging-ammeter.html Jeff
