gregmcc said:
I've just received my inchworm kit and its almost completed but have a question on some of the component values. In the pdf file the capacitors listed are ...
I get this asked a lot. Used to have a forum where it was explained, but when I redid the site, I removed it for the moment and will take me some time to get it back.
Although Blueroom developed the Inchworm, the version you bought from dipmicro is completed by us and I made educated changes to accomodate the inventory we had on hand. These substitutes have been tested, William is aware of them and he fully supports my changes.
C1 is non-critical high frequency filter. I realize the appnote in datasheet uses 0.33uF but this is the last part going to make your Inchworm not work.
C6, C7, C8, C11 are non critical switched capacitors for voltage pump in MAX232. Some earlier versions of this chip required 1uF or even 10uF but ST232 datasheet (MAX232 equivalent) allows anything above 100nF:
https://www.st.com/stonline/products/literature/ds/6420.pdf
C9 is the filter of multiplied voltage with non-critical value. Value above C6, C7, C8, C11 will do the job.
After I assembled my unit, I measured the ripple under load on these substitutes and there is none.
Hope this helps