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  1. D

    Oscilloscope and AC home line noises

    If you read the ap note on Isolated measurements that will describe the ground problem when doing measurements on non isolated systems, like a SMPS for example. Regards, Dana.
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    Oscilloscope and AC home line noises

    Using scope probes : On probing, 15 cm for high speed stuff, which a micro is asking for misinterpretation. See the following on probing considerations (section page 46 on ground lead length) : https://download.tek.com/document/02_ABCs-of-Probes-Primer.pdf...
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    Transient noise and microcontroller

    The 6V rating is the max. Its what you must observe to not have a worst case chip not fail in situ. Your post of scope capture did not seem to make it onto this thread..... On probing, 15 cm for high speed stuff, which a micro is asking for misinterpretation. See the following on probing...
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    Oscilloscope and AC home line noises

    Could be ground bounce or could be induction via a relay with no snubber or clamp diode turning on and off, and bouncing when it does. On another topic be careful how you probe in AC line applications : https://www.newark.com/pdfs/techarticles/tektronix/FFM.pdf Regards, Dana.
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    Transient noise and microcontroller

    Its 6.5V which is out of spec for chip, but fairly narrow width, so you might be OK. Another way of doing that measurement is turn on infinite persistence and capture many cycles on screen to get real pk-pk measurement. Greta way of looking at supply rail noise. Atmega has 6.0 Vmax for spec...
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    Transient noise and microcontroller

    Good bypassing at micro pin would be a parallel tantalum and ceramic disk (say .1uF). The best tants are polymer, "Wet Al" = Electrolytics): Lead length short to minimize L which effectively negates the C properties to shunt AC signals and transients to ground. Also where possible a...
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    Transient noise and microcontroller

    Post a pic of prototype board wiring as well. Regards, Dana.
  8. D

    AC 220V MCU TTL Level 8 Ch Optocoupler Isolation Test Board

    Schematic ? Even hand drawn OK..... Regards, Dana.
  9. D

    Resistor wattage confusion

    All depends on the free air (if no blower in system) radiating surface area of the resistor, hence its thermal R value. I know 1W in a TO92 transistor package will not let you hold the body very long, unless you are trying for a tattoo.... Regards, Dana.
  10. D

    Flow Switch for Gasses (such as Air, CO2 or N2)

    MQ series, or concentration sensors : https://robocraze.com/blogs/post/mq-series-gas-sensor Regards, Dana.
  11. D

    CD4017B has the jitters

    What is your relay coil current requirement or DC resistance ? A 1N4148 may be too small a diode for this application. Same for BC547..... Regards, Dana.
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    CD4017B has the jitters

    Spice commands for .tran and PULSE : http://www.hkn.umn.edu/resources/files/spice/VirtualSpice.pdf Regards, Dana.
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    CD4017B has the jitters

    Your relay circuit should include these basic circuit topology and components : I do not see any bypass parts for the chip power pins, like a .1 uF ceramic in parallel with a 10 uF or better polymer tanatalum capacitor. The chip is a micro I presume, have you established a routine to bounce...
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    Problem with ceiling led

    What does circuit board look like underneath, a pic ? Regards, Dana.
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    Switching DC motor with TIP122 and Arduino

    When the V reverses on the L (MOSFET turned off) it ramps very fast to a high V, so diode needed to clamp it before its V gets too high, has to be fast. Thats the reduced explanation as its complicated by the nature of the motor L, its losses, and other considerations. The MBR560 has no reverse...
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    ESP32 wroom32 Bluetooth dBm

    Some calculators : https://www.immersionrc.com/rf-calculators/ https://www.l-com.com/resources%2Fwireless-calculators Regards, Dana.
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    TFT touchscreen lcd display replacement info

    What you might do is post at Renesas, Samsung, Sharp, EDT..... websites asking for a second source replacement. The other possibility is you design a translation board to map Newhaven pinout to another display, providing their signaling same. Left hand column list of manufacturers ...
  18. D

    Switching DC motor with TIP122 and Arduino

    Boy did I screwup, no that diode is not adequate. Something like this : https://www.digikey.com/en/products/filter/single-diodes/280?s=N4IgjCBcoKwwTFUBjKAzAhgGwM4FMAaEAeygG0R4AGKgAgDscQBdIgBwBcoQBVegSw4B5NAFk8GHAFcATnhABfIgE4wAFiQhUkTLkIlylNQHZjVAGwt2XSCADKHGf3oBzRUsqGAJv2Jf5zApAA Basically a...
  19. D

    Switching DC motor with TIP122 and Arduino

    Then the 220 ohm in MOSFET gate should be fine. If you have a scope look at turn off of motor, if you are still getting high V spikes on MOSFET drain then consider adding this as well in parallel with motor and diode, a snubber. https://rudys.typepad.com/files/snubber-e-book-complete.pdf...
  20. D

    Switching DC motor with TIP122 and Arduino

    You driving MOSFET with a PWM ? If so this might help to calc the gate R : https://www.ti.com/lit/an/slla385a/slla385a.pdf?ts=1676742072116&ref_url=https%253A%252F%252Fwww.google.com%252F R18 fine as it is. The diode preferably wants to be a fast diode. 1N4148 for, depending on motor L...
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