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  1. AnalogKid

    Short term battery backup circuit

    The first schematic in the page you linked to is both more and less than what you need. The second schematic seems overly complex. And, a relay is overkill. The current or power draw of the device you are powering should be in a datasheet, product page, molded into the case near the power...
  2. AnalogKid

    Help how to build a dc voltage interrupter to control power on and off time. PWN not sutable.

    But I digress . . . Your max overall timing period is 70 seconds. That is a bit long for a simple R-C timer, but not terrible. 1% tolerance resistors are cheap, and 1% tolerance capacitors are reasonably priced at Mouser. The CMOS version of a 555 (LMC555) has much higher input impedances...
  3. AnalogKid

    Help how to build a dc voltage interrupter to control power on and off time. PWN not sutable.

    Hold on there, sparky. "vacuous" - ? Not even close. In fact, his comment conveyed *the value of your response to him* with clarity and precision, so it had useful substance, the exact opposite of a vacuum; something your response to him lacked. He did not understand your response, while you...
  4. AnalogKid

    Help how to build a dc voltage interrupter to control power on and off time. PWN not sutable.

    Completely agree. Now you've stepped in it. When I first started bouncing around forums, it seemed like every other "solution" completely ignored the OP's skill level and/or design requirements, and went straight to either a uC or a 555. Hence, my tagline is "Maslow Antagonist". Here's why...
  5. AnalogKid

    Home assignment

    Once you're done 1 and 2, redraw the schematic in a more conventional manner. Start with the current source to the left, with any resistors directly in parallel with it. Extend the + and - (GND) rails to the right, and then fill in the remaining resistors and equivalent resistors. The +...
  6. AnalogKid

    Help identifying old lab equipment

    Construction suggests a vintage one or two decades older, like pre/post WWII. Could be a precision adjustable resistor peripheral for an analog computer. ak
  7. AnalogKid

    Bench psu build

    PG = Power Good. ak
  8. AnalogKid

    Spectrum analyser Equalizer project how to go about it?

    Impressively steep walls. Corresponding phase plot? ak
  9. AnalogKid

    Spectrum analyser Equalizer project how to go about it?

    In Other Words
  10. AnalogKid

    Spectrum analyser Equalizer project how to go about it?

    The bandpass filters in the article do not have a very narrow frequency response. IOW there is some overlap between the response bands. If you increase the number of bands, the overlap will be worse. For example, if you have one band centered at 1 kHz, and you input a 1 kHz sinewave tone, it...
  11. AnalogKid

    Spectrum analyser Equalizer project how to go about it?

    Upper right - "6 to 12 Volts". ak
  12. AnalogKid

    Spectrum analyser Equalizer project how to go about it?

    He wants 30 frequency bands, each with an LED bar graph, not a single indicator with 30 steps. ak
  13. AnalogKid

    Spectrum analyser Equalizer project how to go about it?

    PDF scans of the magazines. Fun fact - For the same month and year, two different international versions of the same magazine had two different audio spectrum analyzer articles. Hmmm . . . Canada: https://worldradiohistory.com/CANADA/ETI/70s/ETI-CA-1978-06.pdf England...
  14. AnalogKid

    help with a 12v control circuit

    Relay coil current or resistance? Also, what if someone steps on the mat after everything is up and running? Wouldn't the latching relay go to the off state? ak
  15. AnalogKid

    help with a 12v control circuit

    This could be a simple as adding one capacitor, but not without more information. For your relay - manufacturer / part number / coil current / coil wattage / datasheet / link to product page - anything - ? ak
  16. AnalogKid

    Trying to identify what these are

    Almost all small, low-cost electret microphone cartridges have a FET buffer built in. Two wires means you need an external bias current resistor between the audio out connection point and a low DC voltage. What is the operating voltage of the system you want to build? ak
  17. AnalogKid

    LED Supply Mounting

    I don't see any air vents in the enclosure, an interesting design choice. Sometimes, empirical data trumps a datasheet. Try this --- Get one, put your max load on it, put it in a shoe box with the lid on, or something smaller that approximates the air volume it will be trapped in, and come...
  18. AnalogKid

    Speakers and Bass Frequencies

    Wow. Speaking of color-blind . . . ak
  19. AnalogKid

    How to test 24v on this plug

    The way the connector is laid out suggests that there might be two independent 24 V outputs. ak
  20. AnalogKid

    Speakers and Bass Frequencies

    By that definition, the 85% of the world's population that is not at least partially color-blind is in fact color-blind. You are confusing a normally-functioning sensor that has both normal and abnormal ranges of response with the response of a theoretically perfect sensor that does not exist...
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