• RE: 12v Solar battery monitor

    @nurul-amira Yes that should all work fine. That circuit has been running 24/7 for around 4 years now without any issues.

    posted in My Project
  • RE: 💬 The Harvester: ultimate power supply for the Raybeacon DK

    I've confirmed Julien's results. I procured a board that's inferior to his but with the same chip on it, and with no load other than its LED it can remain operational as low as 15mv. With that as the input voltage, the output voltage is around 640mv, so I think the reason my board can't survive on less than 15mv is that when the output voltage dips below about 600mv then the chip no longer has enough voltage to switch. Compared to other off-the-shelf chips, this is an impressive result, and even more so considering that these chips only cost around 8 cents each in small quantities.

    posted in OpenHardware.io
  • RE: 💬 The Harvester: ultimate power supply for the Raybeacon DK

    Julien stumbled across an inexpensive PFM boost converter board which he demonstrates is able to boost 65mv up enough to light a red LED:
    eBay Cheap & Cheerful: #3 - DC/DC Boost Module 5V Out – 07:44
    — Julian Ilett

    I can't discern from the video what the minimum start-up voltage was, but it's quite a surprising finding anyway, because on its face it would appear to outperform most of even the energy harvesting chips on the market with respect to minimum operating voltage!

    Edit: In a subsequent video, Julien found that the start-up voltage was 560mv (the datasheet only promises 0.9v as the minimum, so maybe Julien got lucky with his particular device):
    Update: Cheap 5V Boost Converter Performance – 06:58
    — Julian Ilett

    but he's able to keep it running (albeit with just a 1.2v output and little to no load) on what he says is an input voltage of as little as 10mv. That matters because by keeping it running it sidesteps the start-up voltage requirement, and if the input voltage rises it can start being useful much sooner than having to wait for a minimum 0.56v input voltage to be reached. What would be interesting to know is just how much power is required to keep it running, even if only just for this purpose.

    The switching chip is the E50D, which Julien's research indicates may be a CE8301.

    posted in OpenHardware.io
  • RE: [SOLVED] High battery usage (Pro-Mini / RFM69 / Si7021)

    The product listing for the step-up that the OP is using says:

    Sucks the juice out of your batteries.

    Sounds like it delivers on what it promises.... 🤣

    posted in Troubleshooting
  • RE: CNC PCB milling

    I found a good "once and done" lubricant for my CNC called Krytox. It's made by Dupont, is non-toxic, never dries out, and is non-reactive with just about everything. It is more or less liquid teflon (PTFE). It comes in a wide spectrum of different viscosities. I'm using GPL105, but I think for a CNC one could argue for using a version that's a least slightly more viscous (i.e. GPL106 or higher).

    There also exists grease versions of Krytox, so perhaps (?) that would be even better. In general, for any given lubricant, how does one decide what the right viscosity is to use?

    posted in General Discussion
  • RE: CNC PCB milling

    I've played around with the Ustepper-S now, and as near as I can tell, it is working correctly in closed-loop mode without issue. After the execution of each command, it shows error of 0.00, and it maintains closed loop operation to maintain its position even after the execution of the command, as it should. In my testing, Servo42A fails to do that, as well as having other problems, including lack of response to posted github issues.

    Ustepper-S incorporates PID, so it should be able to do rapids and yet stop exactly where it should. Again, my initial impression is that seems to be the case.

    I'm ordering UStepper-S for the x and y axis as well, which unfortunately will again take weeks to receive. However, I expect this will be the last stepper driver upgrade that I will ever need to do. If I later decide to upgrade to NEMA-23, the same UStepper-S can be used to drive it and only a different bracket would be needed to position it on the back of the NEMA-23.

    posted in General Discussion
  • RE: CNC PCB milling

    I received some Sharpie-Oil "Extra Fine" pens. Testing them, they have a 1mm line width, so they'd be no good for filling in features smaller than that. AFAIK, they have the smallest tips in the Sharpie-Oil series.

    I received the 16-bit closed-loop uStepper hardware from Denmark, so I'll be testing that sometime soon. I intend to use it on the z-axis, since accuracy on depth of cut is critical. If even this is still not enough, then I'll work harder to identify the source of the error and, if appropriate, consider stronger measures like low run-out collets, low-runout bits, ball-screws, tighter linear rails and/or tracking absolute position with a DRO and/or possibly a different spindle.

    posted in General Discussion
  • RE: CNC PCB milling

    @Joerideman said in CNC PCB milling:

    @NeverDie I saw an YouTube video screenprinting. That guy noticed that semi transparent sheets work better than transparent sheets. Ink holds better or something.

    I can actually try this one out. Because afteral. We want that 0.4mm pitch right?

    I just need to find something to put the paint on.

    Which thing are you planning to try? Sharpie-Oil on a semi-transparent sheet, or the uv resistant inkjet ink, or...?

    For enhanced laser printing I found this: https://ikonartstencil.com/toner-enhancement-spray/
    though I have no idea how well, or even if, it works.

    posted in General Discussion
  • RE: CNC PCB milling

    Reporting back: After letting it dry overnight, I discovered that the Sharpie-Oil apparently shrinks and then flakes off of the PP film:
    p0.JPG

    Not sure if it behaves better with other films or not.

    However, before it dries, it performs great, as seen below.

    Here I am squishing solder mask between two thick sheets of glass:
    p1.JPG
    This technique seems to do a reasonably good job of producing a uniform thickness of the UV solder mask.

    Here I use a Sharpie Oil marker to print the word OIL and place it over the flattened solder mask before exposure to UV:
    p2.JPG

    I exposed it to UV for a full 99 seconds, which may have completely cured the non-masked solder-mask. Here is how it looks after I removed the "OIL" mask:
    p3.JPG

    Here is how it looks after peeling back the top layer of PP film:
    p4.JPG

    I then removed the uncured solder mask using IPA, after which I cured it some more under UV just to be sure:
    p5.JPG

    As a first attempt, not bad! Using a high opacity mask probably helped quite a bit.

    So, I guess now the question is: which inkjet ink/pigment or which laserjet toner has the highest opacity? For instance, there is this which claims to be: https://www.amazon.com/Ink-Dynasty-Resistant-Refillable-cartridge/dp/B00E3PAUXA
    or this:
    https://www.screenerschoice.com/index.php?route=product/product&product_id=157

    From the looks of it, the answer will be some kind of inkjet black pigment, which is consistent with the results I got from comparing ink pens vs paint pens above.

    posted in General Discussion
  • RE: CNC PCB milling

    For purposes of solder masking, I compared a number of black markers for drawing on PP sheeting to see which would be the blackest and most opaque. I compared: Inkzall, regular Sharpie, Sharpie Oil, and POSCA (a Japanese paint pen). By reputation I had thought the POSCA would win, but by far the blackest and most opaque of the bunch was the Sharpie Oil. It appeared to be genuinely opaque. The Inkzall and the regular sharpie were not opaque at all.

    posted in General Discussion