Fernando Correia
For which reason do you think you are loosing 10% at each port, each time you add another port into play??
January 11, 2015
Jorge Pereira
Efficiency. Or lack of it. The internal drivers are never linear. Even MOSFET power transistors start deviating after some threshold value. I don't know what driver circuits are used in SBrick but it seems that 3A is the magic number.
January 11, 2015
Fernando Correia
Information about drivers here:
https://social.sbrick.com/wiki/view/pageId/14/slug/hardware-and-firmware-versions
January 11, 2015
Jorge PereiraThanks.. The datasheet (http://www.ti.com/lit/ds/symlink/drv8835.pdf) has no charts so I can't say much more. But since they use the same as LEGO PF IR v2 and Philo made a very detailed analysis (http://www.philohome.com/pfrec/pfrec.htm) I noticed that... moreThanks.. The datasheet (http://www.ti.com/lit/ds/symlink/drv8835.pdf) has no charts so I can't say much more. But since they use the same as LEGO PF IR v2 and Philo made a very detailed analysis (http://www.philohome.com/pfrec/pfrec.htm) I noticed that he tested v2 with 2.7 Ohm load (mine is 4 Ohm) and «Thermal protection trips at 2.2A». Then he did the same with 4 Ohm + 5 Ohm load and «If the second output is loaded (1.3A), protection occurs at a lower current (1.6A). This again shows that it may be a good idea to avoid grouping together powerful motors on the same receiver.» Simillar to my findings but for some reason SBrick seems to behave better. less
https://social.sbrick.com/wiki/view/pageId/14/slug/hardware-and-firmware-versions