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Mismatched schematic and video in lesson 5? Or am I crazy?
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Mismatched schematic and video in lesson 5? Or am I crazy?

by obscurite on Fri Mar 14, 2008 11:24 pm

First of all, I've had SO much fun assembling and playing with this kit so far. Thanks ladyada - you are amazing!

The head scratching began at Design Challenge 1. The schematic says that the switch connects to both a 100 Ohm and 10k Ohm resistor, however the video, and subsequent videos below, show a design using only the 10k resistor as the pull-down.

Both designs work fine, but I think the one in the video is more elegant because it only requires one resistor, not two as in the schematic.

Is there any reason why one is better than the other? I had wondered, before noticing the discrepancy that perhaps you could pull down with just a wire, but when the tutorial says that the low pull "is better than nothing" I figured there's a reason you wouldn't use just a wire.

With my relatively little experience, I found it confusing, because I went and built the schematic, only to see that it didn't match the video, but at least both work!

UPDATE:
I realized the 100ohm resistor is only there to protect the pin, so that mystery is solved. I also realized that it's a pull-up, rather than pull-down. However, it may save some other folks some confusion to post a schematic that doesn't feature the 100ohm resistor. Here is one, which is a modified version of the one in the tutorial.

Image
obscurite
 
Posts: 3
Joined: Fri Mar 14, 2008 11:03 pm
Location: New Haven, CT / NYC

Am I the only one who had these questions?

by obscurite on Thu Mar 20, 2008 11:55 pm

Actually it looks like someone else posted a similar question in another thread shortly after mine. I've been back here every day for the last few days hoping to see someone confirm, or elucidate my findings.

Anyone?
obscurite
 
Posts: 3
Joined: Fri Mar 14, 2008 11:03 pm
Location: New Haven, CT / NYC

Please be positive and constructive with your questions and comments.