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No electronic background here, trying to get the stuff.

Posted by GAZ082 
No electronic background here, trying to get the stuff.
September 20, 2013 12:59PM
Hi guys. I'm going through the BOM, checking prices here and there (i want to compare how much would cost me to get the parts on ebay piece by piece compared to get kits, with top quality components) and i found the capacitors come in a different variety of voltages with the same F value.

The model suggested in the BOM are basically physical sizes, should i match that size and then see what voltage is the correct one? The maximum working Voltage should be the same or above the input Voltage of 12-35 V (if i recall correctly) the Arduino may take.

Any recommendation is welcomed! Thanks!
Re: No electronic background here, trying to get the stuff.
September 21, 2013 12:46AM
You can use 10V or 16V caps for C1, C5 and C8, no matter what voltage you're running. These run off power from the Arduino Mega (5V) so they'll be fine.

I would recommend 35V or 50V caps for C2, C3, C4, C6, C7, C9 and C10 if you want to run 24-29V. If you're only intending to run 12-18V, I would recommend at least 25V caps, though you could use 16V caps if you really never intend to go over 14V.

Note: The Pololu's are only rated to 30V, while the DRV8825's are rated to 35V. You should always leave yourself some wiggle room at the top end of your voltages, especially for caps.

Also: If you're simply running your heated bed at >14V (and running your motors/hot end at <=14V), you do not need to worry about higher voltage caps. All of the caps run off the 5A power connector, whereas the heat bed runs off the 11A connector.

PS: In all these cases, you can always go for higher voltage caps than I've recommended. In fact, you will probably find that certain higher voltage caps are cheaper than others. This is simply due to economies of scale affecting the price of what people use a lot. So if you find that 50V caps are cheaper than 35V caps of the same type, just go with the 50V version.
Re: No electronic background here, trying to get the stuff.
September 27, 2013 11:52AM
Thank you for the tips! I went with a DIY RAMPS kit from Ultimachine. I expect them to have quality components. Later found already complete RAMPS on eBay for 30 dollar less, but i'm pretty sure they will have lower quality components, at least that's what i hope!
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