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Thread: Phil's Dimmer

  1. #21
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    Default Re: Phil's Dimmer

    Quote Originally Posted by P. Short View Post
    Just for future reference, that 100μF capacitor is a bit of overkill. I think that a 10μF, 250V cap would do. With a 120VAC power input the voltage on the cap is about 180VDC, and the current through the 100K+5K resistor is then about 1.8mA. Using the usual formula for voltage drop across a cap (Δv=IΔt/C), the voltage drop (pessimistically) is 1.8E-3 * 8.3E-3/0.8E-6 = 1.8V (correction: 1.8E-3 * 8.3E-3/8E-6 = 1.8V - result was previously correct, arithmetic was wrong), which would not have any effect on the IGBT transistor (which is all that matters). And I think that even a 1μF, 250V cap would be fine (especially if the 5K resistor is increased slightly in value to perhaps 6.8KΩ). A somewhat more economical design would place a lower-voltage cap in parallel with the 5KΩ/6.8KΩ resistor instead of where it is in the circuit given in that video.

    Of course, this comment will be lost to posterity because it's not in your igbt/triac thread...
    It is great to hear of your progress with arduino coding an willingness to stick with it on your dimmer.

    Thank you for the parts advice Phil.I did take your advice on the opto .

    I should have posted the video in the other thread ->deleted.
    Last edited by P. Short; 07-08-2021 at 02:17 PM. Reason: Value in arithmetic for capacitance - 10uF (-20%) s/b 8E-6F

  2. #22
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    Default Re: Phil's Dimmer

    This is still an active project for me.

    Is there a way to program an Arduino Uno that leaves a range of flash memory unchanged? This would be used to either preserve the dimming curve tables themselves or to preserve parameters for the code to create and write those tables to flash the first time after new code is downloaded.
    Phil

  3. #23
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    Default Re: Phil's Dimmer

    There are a couple was to do this. Are you using the "FS" space? Also sometimes known as the EEPROM space (actually in a reserved flash segment) and will NOT be cleared when you upload a new operational image. Most people put a SPIFFS or LittleFS file system in that space but the use of the space as EEPROM is still available. AND you can create a default image to upload into that space so you only have to read it in your operating code.

    Alternatively you can create a custom hardware definition and set aside an integral number of blocks (block size depends on your hardware) in the hardware description file. This causes a problem if you plan to use OTA. In OTS the effective code size is halved and when you upload a new image the system switches partitions. If your tables are in the code space then they would "Vanish" when you upload an image using OTA.


    2021 New Tune-to sign. New 40x27 matrix at the house. Retiring the Strip based matrix. Updating some of the old window frames to the new house. Adding two new songs.
    2020 Full sized show reworked for the new location. Only adding (famous last words) 13 RBLs that I finally got converted to using pixels
    2019 - Just moved into a new home (yet another change of plans). Will be dim but not dark. Too much to do at the new place to leave time for a show. Dim show (3000 pixels) had regular visits most nights.
    https://www.youtube.com/user/MartinMueller2003

  4. #24
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    Default Re: Phil's Dimmer

    Looks like I'll have to do some reading to find out what OTA and OTS mean. Presumably OTA is 'Over the Air', but OTS puzzles me.
    Phil

  5. #25
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    Default Re: Phil's Dimmer

    ots is what you get when your finger misses the a key


    2021 New Tune-to sign. New 40x27 matrix at the house. Retiring the Strip based matrix. Updating some of the old window frames to the new house. Adding two new songs.
    2020 Full sized show reworked for the new location. Only adding (famous last words) 13 RBLs that I finally got converted to using pixels
    2019 - Just moved into a new home (yet another change of plans). Will be dim but not dark. Too much to do at the new place to leave time for a show. Dim show (3000 pixels) had regular visits most nights.
    https://www.youtube.com/user/MartinMueller2003

  6. #26
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    Default Re: Phil's Dimmer

    The settings in the picture below are for my particular device. These settings are defined in a board manager file for your platform. To create a custom setting you create a custom platform with the settings you want.
    Attached Images Attached Images


    2021 New Tune-to sign. New 40x27 matrix at the house. Retiring the Strip based matrix. Updating some of the old window frames to the new house. Adding two new songs.
    2020 Full sized show reworked for the new location. Only adding (famous last words) 13 RBLs that I finally got converted to using pixels
    2019 - Just moved into a new home (yet another change of plans). Will be dim but not dark. Too much to do at the new place to leave time for a show. Dim show (3000 pixels) had regular visits most nights.
    https://www.youtube.com/user/MartinMueller2003

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