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  1. AnalogKid

    Need circuit for sine-to-square/sawtooth generator

    Why not? ak
  2. AnalogKid

    Questions regarding H-bridge

    Actually, something north of 1000 V. ak
  3. AnalogKid

    How to make composite video black and white?

    Waving "composite video" in front of me has consequences. ak
  4. AnalogKid

    How to make composite video black and white?

    Same effect, yes. B.U.T . . . Analog video runs around on controlled impedance coaxial cables for a reason. The reason is a butt-load of math, but the problem is the termination resistors at each end of the signal path, and the quality(?) of the VGA driver circuit. There probably is a 75 ohm...
  5. AnalogKid

    A Phoney Question

    You should be able to pick up the audio signal on the two wires going to the speaker. A possible issue is grounding, but the handset always is battery powered so you probably can get away with this. My V-Tech handset has a 2.5 mm TRS jack, so if I were doing this I could just plug into the...
  6. AnalogKid

    Does anyone know what this is?

    More photos. Different angles, zoom out a bit so we see the component in the context of other components around it. Any markings on the other side of the part? First guess, a noise suppression capacitor, or maybe a surge suppressor. ak
  7. AnalogKid

    2N2222 questions

    Not really. I disagree with "safely". 800 mA pushes the device to its absolute limit, and requires that the package be maintained at a relatively low temperature. Yes, it will work - for a short while. 1. 800 mA is its "Absolute Maximum" collector current rating. No device should *ever* be...
  8. AnalogKid

    2N2222 questions

    None taken. ak
  9. AnalogKid

    2N2222 questions

    The OP set the resistor value, not me. We have zero information about the LED or the desired current level, so there is no way to evaluate the appropriateness of the resistor value. Current levels in the LEDs, the resistors, and the transistor are three different things. The question was...
  10. AnalogKid

    2N2222 questions

    Ohm's Law plus third-grade arithmetic. In order: What is the circuit voltage? What is the voltage drop across an LED (Vf)? What is the voltage across the resistor? What is the current through the resistor? What is the total current through all resistors? What is the collector current rating of...
  11. AnalogKid

    Equivalent resistor

    No. We do not give away homework answers, especially when the student hasn't done anything. Please show us your work so far, and we will comment on that. Also, Iq and Uq are not industry standard symbols. Is Uq a voltage source, a current source, or something else? ak
  12. AnalogKid

    Power Transistor Code Identification help

    The part was made in December of 1982. Back then it was a semi-common practice for manufacturers to have transistors marked with "house numbers", their own company's internal part number rather than the industry standard number such as 2Nxxxx. Theoretically, this made it more difficult for...
  13. AnalogKid

    Preventing a possible 12v short circuit

    That timer has + and - inputs and + and - outputs. When the timer is *off*, is there any continuity between the input and output terminals? For example, are the two - terminals connected all the time, and the timer breaks only the connection between the + terminals? ak
  14. AnalogKid

    MOSFET problem

    Connect the gate to the source and remeasure in both directions. ak
  15. AnalogKid

    MOSFET problem

    Do you have any information (or feel) about what the part is doing in your device? For example, is it part of the power supply? If so, then it could be a part of a switching circuit, or a linear regulator. If it is acting as a DC switch or linear regulator, then there are many workable...
  16. AnalogKid

    need help electronic/relay problem phone horn

    The photo helps (!). With the speaker unplugged and the ringer volume set on max., what is the voltage on the connector pins? ak
  17. AnalogKid

    need help electronic/relay problem phone horn

    Remove one (or both) wire(s) from the speaker and measure the voltage again. For completeness, make two measurements, one with the meter in AC mode, and one in DC mode. ak
  18. AnalogKid

    AC/DC Adapter Question

    The two images did not post, but the link works. So does the adapter. That is an unregulated linear power supply. Transformer >> rectifier >> filter capacitor. The average value of the output voltage will drop to the rated value when the output current is at or near the rated value...
  19. AnalogKid

    It's Been a Long Time.....question

    While the perf-metal speaker grille probably is not grounded, it still is a large capacitive plate you can charge up, drawing charge out of your fingers. Touch the grille first, then the know, and see if it makes a difference. ak
  20. AnalogKid

    Energy transfer problem

    Not. Because the theorem applies to a constant-voltage source with infinite current capability. The effects of the theorem appear when the load impedance is nearly equal to the source impedance. If we assume that the battery output impedance (ESR) is 0.1 ohm, and the load is 14.4 ohms, then...
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