Recent content by rq3

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    hippy's phenomenal patience, technical expertise, and diplomacy (and his apparent ability to live on 1 hour of sleep per day) make him a true guru. I miss his wisdom, and look forward very much to his return. While I am at it, folks like Alleycat, kranenborg, westaut55, PhilHornby, and others...
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    board design

    As oracacle said, it's not normally considered "good practice", but it is commonly done, especially on cheaper consumer grade boards. The problem is that the via tends to wick solder away during the reflow process, potentially starving the solder joint. If you decide to do this, use the very...
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    Editor 6 on Windows 10

    For a totally different device, I was recently forced to purchase a Dell laptop running Windows 10 (I generally run XP on a 20 year old laptop, or Unix on an HP server). After spending several days stripping out the bloat code that came with the new machine, reloading Windows, and getting...
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    Can High LED Current Actually Burn Up Output Pins?

    Erco, probably not. It's trivial to measure the source/sink current capability of a particular pin. Set the pin HIGH, and pull it to ground with a potentiometer or decade resistance box. When the pin voltage gets pulled to 1/2 of the supply, the pot or decade box value will be equal to the...
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    Speed counter

    Does it have to be a magnet and hall effect sensor? This looks like a perfect job for an optical switch, with the fan blades chopping the beam from an LED to trigger a phototransistor. Much simpler, and no balancing issues for the fan.
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    Electronics - help needed please

    A fixed linear regulator like your 7805 "leaks" a constant current (usually about 25 microamps) out of the ground pin, and that current is a function of the output voltage. The regulator does its thing by controlling the output voltage so that the ground current is the constant value it was...
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    5 volt regulated Supply

    I have what looks like a 30 volt/30 amp (1 KW) supply from the same manufacturer. They're all over the Bay, and seem to work pretty well. I've had mine for years, and it works well for everything from micro-welding, to massive lead-acid battery charging, to electroplating and anodizing, to...
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    Surface mount components

    Generally, a PC Fab house will accept a BOM (Bill Of Materials) that specifies a particular part by manufacturer and part number OR EQUIVALENT. You can realize an enormous savings in cost by accepting their interpretation of acceptable parts (say, standard ceramic or tantalum capacitors, or...
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    Flux left on circuit boards

    Not just alcohol. ISOPROPYL alcohol, often called IPA. Here in the states, it's available in various "grades", usually 70%, or 90%. The 70% is what the nurse swabs your arm with before a shot, and the 90% is considered a bit too "strong" for application to skin. ALL alcohols are hydroscopic...
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    Ebike problems

    Your issue may be that you are using a MOSFET to raise ground, rather than get rid of D3, and just switch the motor supply directly to common ground. In other words, the logic is reversed. Unless the grounds are top notch (and they ARE massive current conductors in this case), switching the...
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    Flux left on circuit boards

    This is one of those items conducive to the home experiment. Pure rosin is easily and cheaply available at any music store, as it is universally applied to violin bows. A good sized block costs a few dollars. Break off 3 chunks. Place one in a small bottle of water, another in a small bottle of...
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    Flux left on circuit boards

    True rosin for rosin cored electronic solder is basically purified pine sap, and is not designed to be left on the circuit board. It does absorb moisture from the air, and can lead to the issues you are seeing. The solid rosin is dissolved in isopropyl alcohol, which is also an effective solvent...
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    Compensating TOUCH16 values due to supply voltage variance.

    Here is a some "auto-cal touch" code stripped from a much longer effort I wrote years ago. I'm not even sure what the intent was anymore, but the circuit had four touch switches fabricated from a printed circuit board, under a 1/16 inch thick cover glass. There was a bunch of other stuff in the...
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    Bar graph display on SSD1306 OLED

    >SNIP< I have to confess to feeling pleased with myself - And you should! Really nice job, especially since you did it yourself without running for help at the first glitch (like I do). And all of the notes you took during the process will let you help others. Good job.I like the logic and...
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    PCB Layout

    rxhul, no-one knows. Please forget all about that very bad, terrifically horrible layout, and spend an hour or so to learn how to make a schematic and proper printed circuit board layout with whatever platform works for you. Asking the forum to guess why someone else did something wrong is a...