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Anyone know what this resistor is?

I am working on the eye controller board of the hexapod robot and it has some resistors on it. The parts list calls for 12 220 Ohm resistors but, based on the photos, there are more that what it shows in the text. The 12 near the top of the board I know are the 220 Ohm ones, but I do not know what the others are. The 2 vertical ones near the bottom I believe are 20 Ohm and the horizontal one closest to the bottom 220 Ohm. The 2 located underneath the 28-pin sockets are half-covered by the plastic. Does anyone have a suggestion on the value of these resistors? I included a picture of the board from the instructable page and circled the resistors in question.

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I can't see the colors.

So here is a resistor color code that includes 4, 5, and 6 band resistors if you can see them.

Joe

resistor-color-code.png
Arya42 (author)  Josehf Murchison2 years ago

That is also my problem. I was wondering if anyone had suggestions on figuring out unknown resistors.

You should have added a link to the Instructable you were following in your question.

First to answer the questions he did not which I think is bad form for a prize winning Instructable.

That is partial board.

The electrolytic capacitors should be 47 uF.

The circuit board is modeled after Arduino UNO ATMEGA8.

I consider it bad form not to include a schematic of a custom circuit board.

Ok I figured this out by comparing the Arduino UNO schematic and his circuit board.

Under the ATMEGA8 is a 1 kΩ resistor and the one you marked 20 kΩ connected to the reset is 10 kΩ.

This basic circuit should do you the only difference he made was the 470 Ω to the LED is 1 kΩ and the 100 nF on the VCC and GND is missing. I am guessing on the electrolytic capacitor it could just as easily be 100 uF.

Instructables should be reproducible otherwise they are not an Instructable.

Joe

ATMEGA8 basic circuit..png
Arya42 (author)  Josehf Murchison2 years ago

Thank you for your detailed answer. I guess I forgot to mention what instructable I'm doing :) I got some 470 uF electrolytic capacitors as I learned to get bigger ones if unsure of the value. Let's see if I understand this correctly: two under Atmega are 1k ohm, one connected to reset is 10k ohm, one on the left side is 20 ohm and the rest are 220 ohm. I agree with your opinion. While it is a detailed project with lots of photos, it is missing a lot of important details. After looking through it, I'm not even sure if all of the necessary Arduino sketches are included. Hopefully I can get it to work, as I have started it already, even though it is somewhat above my current electronics knowledge (just starting college).

Good luck.

does that mean you are going to mark me best answer?

Joe

Arya42 (author)  Josehf Murchison2 years ago

yes

I almost forgot to mention large capacitors can increase shutdown time since they hold a charge until the charge is drained off.

Joe

You need to ask the creator of the instructable about that. If they instrctions are not clear ask for more info in the comments section.

Arya42 (author)  mpilchfamily2 years ago

I tried asking other questions about things that were unclear in this project but the author did not respond to them (his activity on the comments was over a month ago). I saw that his username is an email address so I tried asking about the code through that but have not gotten anything.