OpenSprinkler Forums Comments, Suggestions, Requests 1.42u parts list misleading and wrong

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  • #22578

    phjr
    Member

    Hi,

    I’m building 1.42u from scratch (not from kit) and I have used the parts list at this url to obtain the parts:
    https://docs.google.com/spreadsheet/pub?key=0AitpZitJ432wdEc4VGNRYmdfclBZWU5Zbm9nWk9pR1E&gid=6&output=html

    During the build, I found that the list is quite misleading and wrong. Errors I have found:

    – X1 is not listed
    – all RN values do not match what is in Eagle schematic

    Unfortunately I found that the RN values are wrong after soldering two of them to the board. I gotta tell you, it’s not fun to desolder those things.

    Anyways – thanks for the very nice project, I was trying to build something like this until I found this one – great stuff 🙂

    Peter

    #25212

    Ray
    Keymaster

    Peter, you don’t need to desolder the resistor networks: the values indicated in the part list are correct. Yes, they don’t match the schematic, but those values work too. Let me explain:

    RN1 contains 4 pullup resistors. 10K is a standard pullup resistor value.
    RN2 is for button detection, since it forms a voltage divider network, any resistor value would work
    RN3 and RN4 are current limiting resistors for the triac, either 220ohm or 330ohm works.

    You shouldn’t think that there is only one correct value for each resistor: the matter of fact is resistors can often vary across a pretty wide range of values.

    #25213

    Ray
    Keymaster

    Forgot to mention: regarding X1: did you check the build instructions of 1.42u? X1 is not used: it is for fixing the microcontroller fuse bits in case you accidentally set the wrong fuse bits. Normally you do not need it.

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OpenSprinkler Forums Comments, Suggestions, Requests 1.42u parts list misleading and wrong