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    arduino digital pin output power question

    Not sure I understand. You paralleling outputs to supply power thru a wire ? If so how distant the load, and AWG of wire you will use ? If so why not just a simple external switch activated by one GPIO pin ? Regards, Dana.
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    Basic transistor switch

    One mod to the post circuit in #1, connect a 10K - 20K R from transistor base to ground. That keeps load off while processor is powering up. Most processors power up with GPIO in tristate, so a floating base of transistor can pick up noise and its leakage could cause premature turn on...
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    arduino digital pin output power question

    Describe your loads ? The I/V requirements. Regards, Dana.
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    Basic transistor switch

    The rule of thumb to force the transistor into saturation is Ib = Ic / 10. Its a term called forced beta in the industry. Generally speaking when we use a transistor as a switch we want the Vce to go as low as possible, so that its power dissipation is kept low and the switch acts as close as...
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    Testing of currents

    1) What is part number of specific micro you are using ? 2) What is range of current you want to measure ? 3) What is resolution of the current measurement you wish to perform ? 4) What is bandwidth of the current you are trying to measure ? 5) Goal Sample rate of your measurement ...
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    arduino digital pin output power question

    Not exactly. It means there is a total limit to the current you can pull thru internal busses, each port having a buss, and the chip the sum of all busses. Its not that a GPIO pin has less drive capability, its the V drop on these internal busses causing internal logic errors, also the currents...
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    Digital Space Noise Detector

    Not a physicist, but would not a Galaxy have more randomness in its noise than a sun ? More total possible states due to more quarks, leptons, atoms..... These questions ? Regards, Dana.
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    arduino digital pin output power question

    From datasheet : Per pin 40 mA, total of all pins 200 mA. And the port limitations : Notice the difference between source and sink limitations of the port. Regards, Dana.
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    Digital Space Noise Detector

    https://www.eevblog.com/forum/projects/noise-source-design-question-aka-_how-agilent-does-the-magic-trick_/ Just out of curiosity if you are storing the noise sampled data values in a flash drive why not just gen them with an algorithm and reduce the problem to D/A side of circuit ? And how are...
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    Animal research project - Load cell switch when reaching a variable threshold

    A good ref book on using IAs, commonly used for conditioning load cells : https://www.analog.com/media/en/training-seminars/design-handbooks/designers-guide-instrument-amps-complete.pdf Here a compendium design resources you could pull from...
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    Help identifying a capacitor

    Cant exactly tell but that cap seems to be bulging at the top ? In two pics I see. That is for sure suspect. You will have to check components connected to it as well, it may have taken out other parts. Regards, Dana.
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    Testing of currents

    Yes you can just use a supply to gen a fixed V into ADC to check your code is correct. But be careful you know that V does not exceed datasheet max on the analog input pin is. Regards, Dana.
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    Testing of currents

    Thats what I would recommend you do. Regards, Dana.
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    Testing of currents

    If you only want the Vshunt x G to input to ADC, eg. reject common mode, then a diff amp is needed. Or you use a processor with a DelSig on it with a differential front end, like this : Regards, Dana.
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    Common Emitter Amplifier - and Diagnosing Problems with an Oscilloscope

    What do you measure with a voltmeter, no signal input to Transistor, on the collector and on the emitter ? A tool for transistor biasing : http://www.guitarscience.net/calcs/ce.htm Regards, Dana.
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    Transfering video using light

    Start google search "SERDES"..... In terminology your "physical" layer is the optical part, the link layer is the translation of analog video to digital and back again, see attached. Regards, Dana.
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    BJTs used as spdt

    Say you have a simple cmos inverter, with a high valued R on its input, the other side grounded. So you think the output should be at "1" level. But if leakage from input protection circuitry, and surface leakage, get high enough it could generate a "1" at input flipping the output to a "0"...
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    BJTs used as spdt

    Divider or zener clamp with a R will do. Ignore the fact its illustrated with a NAND, applicable to logic of MOSFET or..... I would probably not use 470K, leakage concerns generating offset V, but general idea correct. Regards, Dana.
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    Recommendations for a timer switch 12V boat pump

    https://www.amazon.com/s?k=12v+timer&crid=23T6HPX6TSW0H&sprefix=12v%2Caps%2C349&ref=nb_sb_noss_2 Regards, Dana.
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    BJTs used as spdt

    AnalogKids point about running LED current thru base good caution. Looking at a 2N3904, assuming your current is in range of 100 mA or less, there is no absolute max in datasheet I looked at for Ib. But there is a typical graph that looks like 20 mA would be acceptable. Or you could do this...
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