Hi everyone, I'm new to the Uzebox community and have my parts on order through Digikey. However, while reviewing the schematic and Bill of materials, I have some questions and also found a minor typo on the BOM.
This question may already have been answered, but I'm trying to find the reasoning for this:
On the Uzebox schematic, http://belogic.com/uzebox/schematics/Uzebox-rev-E1.pdf
there are 6 capacitors connected in parallel between VCC and Ground C6, C7, C8, C9, C12 and C13) which would sum to 30.3uF of capacitance. In addition, there is a double star (**) recommending to replace the 3 electrolytic capacitors with tantalum caps For optimal video results.
Now VCC should always be 5 volts with 'minimal' ripple due to U8 and the capacitors, but if we used a 33uF capacitor wouldn't it be the same since it would shunt high frequency noise on the circuit to ground?
I thought that maybe we were trying to do a band pass filter, but that doesn't make much sense since the load is everything connected to VCC and the capacitors are shown deliberately by the video encoder.
The only other explanation I could think of would include transmission theory, but due to the short traces, lower frequencies we are running, and that this is a 5 volt DC source, it doesn't add up either.
Capacitors C11 and C16 are paralleled similarly, holding the input voltage before it is regulated to 5 volts at VCC and 3.3 volts at VSS. I would think 1 capacitor would work.
- Regarding the Bill of materials, there is no three star (***) item on the bottom. The last two are both four star (****)