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Topic: Data Logger "Deluxe"
Author	Post
Eric_S 5 posts Popping In	26-04-2008 15:05 Hi All, I put the kit from Elektor together and it worked on the first try. There are only three things that puzzle me. First, there are some posting that suggests that the 2.2k and 3.3k resistors are reversed (since 2.2/5.5 x 5v = 2V not the target 3v that the SD card operates on. My guess is that 2v is good enough to get a logical "1" on the card. Second, when I use it in external trigger mode, the trigger works, but triggers at a voltage somewhere below where I set it. I am not sure what the issue is there. The circuit looks pretty straight-forward and I do not have the zener diodes in to complicate it. Third, the text refers to needing to know how to compensate for voltage drop if zeners are added to protect the analog inputs. Since the inputs can't be used above 5v anyway, I dont see how the Zeners would have any effect. Possibly they would have some leakage dragging down high impedance inputs near 5 V? Thanks Loic Marty / Thanks Elektor
Eric_S 5 posts Popping In	26-04-2008 15:44 Correction. I misunderstood the functions. The triggers work as expected. The external trigger is activated at somewhere about 1.5v. The Save on Maximum function makes reference to the A3 level set by variable resistor P3.
Elektor Editor 501 posts Power User	30-04-2008 20:11 thanks for that Eric. Jan

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