Recent content by Sunnysky

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  1. Sunnysky

    Help validating a 3.3 V resistor heater for BMI270

    The important thermal paths are: Heater to PCB and sensor: Rhs Sensor package and PCB to ambient: Rsa Heater and copper planes to the rest of the board: Rhb Board, enclosure, and surrounding air to ambient: Rba At steady state, the approximate temperature rise is governed by: ΔT ≈ Pheater...
  2. Sunnysky

    Need help

    Skin Effects are a result of internal dielectric Eddy Currents. Proximity losses are a result of external Eddy Currents such as parallel paths of Ferrite touching the conductor traces.
  3. Sunnysky

    How Do You Confirm a Suspected Short on a PCB?

    Usually it is cracked Caps that fail. But the standard diagnostic is to inject an adjustable lab power supply across the node typically 0.5V to 1V. Depending on current and power you can then either trace the voltage drop to the short with a DMM or use a thermal camera or your finger to sense...
  4. Sunnysky

    Need help

    Too many questions unrelated. Pre-exam questions? At 140 GHz surface roughness is a significant addition to path length and losses with eddy current , dielectric loss although skin effect is deeper than sqrt(f) it is still a small fraction of any typical conductor thickness. The best test for...
  5. Sunnysky

    ECU repair

    As long as the output has large Vac, the 1Meg DMM may stop the clock when probing the input pin, it is ok when released. Avoid ESD with a finger on the case.
  6. Sunnysky

    ECU repair

    - with power, the CPU crystal has 2 pins input and output. When measuring on DC both should be roughly half of the chip V+ to ground. On Vac the output should be a full scale square wave , will be x Volts. and not near 0 mV. This is essential. You can inspect the solder for a hairline...
  7. Sunnysky

    Losses in LTSpice

    errors still exist in log after edits ERROR: Node u1:x1:x_rs:m is floating and connected to current source u1:x1:x_rs:G1 ERROR: Node u1:x1:x_rd:m is floating and connected to current source u1:x1:x_rd:G1 ERROR: Node u2:x1:x_rs:m is floating and connected to current source u2:x1:x_rs:G1 ERROR...
  8. Sunnysky

    Small circuit design

    The most efficient solution is to choose a current-limiting resistor that drops X<< 1 V. The R will dissipate 350 mW at 1V, and you should select a power rating at least twice to reduce the temp. rise from 120 to 60 °C above ambient. This demands you choose a power supply that is N* Vled + X...
  9. Sunnysky

    The official Xmas/holiday thread 2025

    https://youtu.be/aH54-DpHeB0?t=1361 New Year's swarm drone show in Yerevan town square. We were there in October when they just had nightly musical colourized dancing waterworks. They do have a company that can control drones for some purposes, and are planning a new drone factory, but this is...
  10. Sunnysky

    If You're an Engineer

    If one takes the time to recognize the pattern on the shell, that will improve your odds but takes just as long. But the odds ought to be 50% unless you forget about precognition bias.
  11. Sunnysky

    Battery treatment

    A cutoff below 20% accelerates the reduction in life recharge cycles rapidly. Short-term gain vs long-term pain. That's why it is shaded in red.
  12. Sunnysky

    The official Xmas/holiday thread 2025

    Greetings with the seasons. May you enjoy the spice of life. I lost the belly this year but my wife says I have no bum left too.
  13. Sunnysky

    Small circuit design

    Here's a method using a Festoon car lamp that is close to the resistance <1 Ohm cold. Reverse protection diode added (opt) Disable can be made active Low with a simple change. Simulation < press continue to destination = Falstad Interactive sliders for Vbat and Lamp Power rating at 14.2...
  14. Sunnysky

    3v step down from 12v

    TL;DR Why bother when you can put 4x 3VLEDs in series and repeat as many in parallel as you want and switch on/off from ground with an NPN. If that isn't enough current or your 12V reg is worse than 2% use 3 in series with a R to drop slightly less than 3V for I=V/R Or do you need 5V for...
  15. Sunnysky

    Best approach to sweep 410-525 MHz? PLL/VCO vs ramped timer vs sweep-IC?

    Best for what? resolution? Phase noise ? cost? Analog Devices ADF4355 or Texas Instruments LMX2594. e.g. https://www.analog.com/media/en/technical-documentation/user-guides/EV-ADF4355SD1Z_UG-805.pdf https://www.ti.com/product/LMX2594#tech-docs https://www.ti.com/lit/an/sbaa653a/sbaa653a.pdf
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