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  1. Externet

    Powerbank battery level meter?

    Or perhaps : ---->...
  2. Externet

    18650 Under voltage protection

    What I do with undervoltage Lithium cells (usually salvaged) that the charger refuses to accept because their voltage is under the minimum acceptable to enable the charging process, is apply 3 to 4 Volts to raise the minimum. Then, the charger accepts them for a normal charging process. Cheap...
  3. Externet

    Cassette Deck Help?

    Does the tape advance in 'play' or still ? Inspect the pinch roller and its drive belt. If advances, check the audio path, amplifier, headphone insertion switch.
  4. Externet

    Creating RF Circuit without using RF modules

    RF modules were developed to fight against the size, labor, reliability, interactions, calibration, tuning, components count and pricing of 'discrete' circuitry. Choosing one method or the other carries the good and the not good of each. You have to deal with them. Explore an amateur radio...
  5. Externet

    Practical vacuum tube signal generator

    ---->
  6. Externet

    How Is This RC Circuit Dropping Voltage

    If 60Hz, the 470Ω resistor plus the 5643Ω impedance of the 0.47μF results in 6113Ω total opposition to alternating current. Calculate as if it was only a 6113Ω resistor in the circuit. The unmarked capacitor to the right also presents a impedance. Both in series to power applied at S1 and S2...
  7. Externet

    Carbon monoxide detector signal conditioning

    Explore using an automotive sensor, dedicated sensors into the tail pipe instead of a hot wire. ----> https://www.parallax.com/product/605-00007
  8. Externet

    Ecu repair

    To repair something, you must know how it works. If schematics or service manuals are not available, you are left to guessing. To guess, Check power supplies, 3.3V, 5V, 12V... whatever is present in the power pins of many ICs. Next, see clocks, data lines activity in memory chips...
  9. Externet

    Ecu repair

    From the maaany ECUs I have dealt with, I have seen only one failed. Because some genius reversed the battery. Ignorance of automotive electronics makes technicians to want to replace the ECU in a total guessing mode. Like in the days of VCRs, they wanted to replace the heads because did not...
  10. Externet

    circuit breaker switched off from distance ?

    A surveillance camera should clear the doubt about someone flipping the breaker. Inspecting the breaker should clear the doubt of being remotely flipped. Replacing the breaker with a non-triggerable type should clear both possibilities. A cover with a padlock should let you sleep in peace...
  11. Externet

    Simple power supply that can be embedded in a wall socket

    Made several, been working 6 years. Simple thin hand carved copper clad board, for pin insertion type switch, self locks in-place, notches on the board allow removal. Low enough profile to fit in existing boxes. Two 0.25W resistors (1K, 220K), 1 capacitor 0.1μF, 250VAC, two 11000mcd white...
  12. Externet

    Simple power supply that can be embedded in a wall socket

    The 1K resistor in the circuit stays. An additional 100K-200K resistor in parallel to C is convenient to implement. The ~ symbol can be across the wall switch terminals. Turns leds on when 'ceiling' lamp is off.
  13. Externet

    Measure distance to water surface

    I would do optical towards something floating on the surface. ---->...
  14. Externet

    LF Amplifier - low power output

    That common mode choke is.... in the power supply ? Are you feeding a high enough level signal to the amplifier input ? If you can raise that input level, what happens ? What is the amplifier consumption current in Amperes while delivering 50W ? Is the 30V stable ? Please measure. It has...
  15. Externet

    Simple power supply that can be embedded in a wall socket

    Or, DIY Better use a 0.1μF / 400VAC capacitor with a 100K resistor in parallel to it for the above circuit.
  16. Externet

    LF Amplifier - low power output

    What components get hot ? The supposed 250W are peak or RMS ? Supplying 30V x 5A = 150 W power in, times efficiency will never go beyond 150 W.
  17. Externet

    Simple power supply that can be embedded in a wall socket

    What you mean is a 'lighted wall plate' ---->...
  18. Externet

    Resistive touch screen film as sensor.

    From what I remember early touch screens, it is two independent resistive paths, a vertical and a horizontal, interpreted as coordinates by the μcontroller. I have a few 4-wire canibalized from old 'Palm' PDAs with need to put to some clever use... A larger area touched under the finger may...
  19. Externet

    round slotted nut tool ?

    Try keyword "destuffing" :rolleyes: tool... ----> https://www.aliexpress.com/wholesale?SearchText=destuffing+tool&opensearch=true
  20. Externet

    Help with circuit

    The 1K resistor should be raised to maintain the same current specified, and it may not shut-off if the base is not connected to emitter with another resistor to ensure it.
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