search

rodneyknaap / atx-turboxt-v3

A new ATX design of an XT compatible PC mainboard
https://www.knaapic.nl/wordpress/1063-2
GNU General Public License v3.0
53 stars 2 forks source link

R26's Value? #2

Open A-Small-Mice opened 3 months ago

A-Small-Mice commented 3 months ago

R26 SYMBOL I am building the ATX Turbo XT according to the given BoM, but I’m having trouble determining the value of R26. Is it 510 ohms or 2.2K ohms?

rodneyknaap commented 3 months ago

I checked this, on my last build I used 510 ohms for R26.

A-Small-Mice commented 3 months ago

Thank you for your response!

A-Small-Mice commented 3 weeks ago

c188_1 c188_2

It seems that the values for C100, C152, and C188 are incorrect. According to the BoM, they should be 100uF, but they actually appear to be 470uF.

-> thanks for mentioning this A-Small-Mice. These capacitors are for improving the power stability, the value is not very critical, but should be sufficient, somewhat higher values are preferable but some variation would be fine. 470µF is perhaps better, or 1000µF if you can find small footprint examples for these positions. The most important voltage is of course the 5V line where more capacitance would always be better.

A-Small-Mice commented 3 weeks ago

r36 R36 (1) R36 (2)

The value of R36 is 470 ohms, but depending on the type of LED used, a higher resistance may be more suitable. When I used a 470-ohm resistor, the white LED was too bright, making it hard to look directly at the mainboard. Switching to a 2.7k-ohm resistor reduced the brightness significantly, but it was still too bright, so I added a cap printed with a 3D printer. In my case, I think a 4.7k-ohm resistor would reduce the LED brightness to a more comfortable level.

rodneyknaap commented 3 weeks ago

Ouch, yes, especially blue or white leds can be painful to the eyes. At my age my eyes have become much more sensitive to this. But everyone should be careful with white and blue LEDs, they are much too bright. So lately I am avoiding these LED colors and prefer to use yellow, red and green LEDs. Maybe it's not so beautiful and modern looking als blue ones but a lot less hard on the eyes. If you think 4,7k is better, do try it out, even a blue or white LED can be "tamed" finally. :) It's amazing how efficient these LEDs are compared to in the 1980s! You also could wire up a potmeter to adjust the LED brightness to your satisfaction, and then you will know the approximate value you need. These LEDs if they are run too high current, they will soon fail and be broken. Also they are much more sensitive to prolonged soldering heat so the faster they are soldered, the better.