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  1. AnalogKid

    Superposition circuits principal?

    Asmost certainly not. Assuming the 3 V battery has a low ESR, it will "short out" the 9 V source, holding its output (and the voltage across the lamp) to 3 V. You don't way what the "high internal resistance" is. If you assign values to the two battery's output resistances, such as 1 ohm and...
  2. AnalogKid

    Can I use a digital potentiometer/remote volume kit in a vintage Pioneer LX-424 receiver?

    umm ... yes, there is. See the schematic in post #4. https://en.wikipedia.org/wiki/Loudness_compensation ak
  3. AnalogKid

    I need a wiring diagram!

    A toggle flipflop starts up with one of the two outputs energized. This can be random, or the circuit can be modified so that it always starts in the same mode. Power is applied to the circuit > Action B starts Press button > Action B stops. Action A starts Release button > Action A...
  4. AnalogKid

    I need a wiring diagram!

    Your question is not at all clear. Are you saying you want to use the relays as logic elements to create a toggle flipflop? ak
  5. AnalogKid

    Two LM7805’s

    ALWAYS check the datasheets for exceptions, but -- The tab of a TO-220 package *usually* is connected to the center pin. This is true for both power transistors such as the TIP series, and 3-pin ICs such as regulators. I've seen some parts where the tab is GND but none of the 3 pins are. ak
  6. AnalogKid

    Math Severity as applied to Serious Electronics

    Feedback and control systems get into some pretty hairy math, including matrix algebra. https://en.wikipedia.org/wiki/Proportional%E2%80%93integral%E2%80%93derivative_controller Network analysis of circuits and systems gets deep into complex numbers for stability analysis...
  7. AnalogKid

    Infrared Illuminator ST96 96 Leds

    Please post all of the writing on the top of the IC package. What is the reason for a photo sensor? ak
  8. AnalogKid

    What kind of switch is this?

    That looks like a pc-board version of an appliance door switch, as in a refrigerator. Is it NC or NO? ak
  9. AnalogKid

    Basic LED blinker Circuit help

    What we are seeing as a short could in fact be two overlapping connections. It might be that the resistor needs to be rotated 180 degrees. ak
  10. AnalogKid

    Basic LED blinker Circuit help

    For the book in post #2, go to document page 27. The upper schematic is a good example of how to draw a 555 circuit. Make your schematic look like that one and your circuit should work. ak
  11. AnalogKid

    110v AC pulse on/off device

    I don't know of any "plug-in timer module" that can turn a load on and off twice every second continuously. That's 173,000 cycles per day. If you know of such a device, please post a link. And - Christmas was a while ago. ak
  12. AnalogKid

    Help identifying old lab equipment

    Narco post: chemically-inspired writing - ? Aren't you up past your bedtime? ak
  13. AnalogKid

    Hacking the op amp...

    You first. What is it we are looking at? What is it from? Was it working when removed? What is the power source? There must have been wires attached to the board, so what did those wires connect to. Some of the silkscreened legend is blocked by components. Please post another view from a...
  14. AnalogKid

    Deadly repair.. hamon crodan

    Confirm that the capacitors are installed with the correct polarity. Next suspect - diodes. Shorted output transistors would blow the fuse without damaging the filter caps. A bulging cap means heat, and that means current *through the cap*, not somewhere else. In normal operation, a power...
  15. AnalogKid

    Traffic

    Your question is not clear. With three lights there are seven possible combination if you allow multiple lights to be on at the same time. If you want only one light on at any given time, that is a different problem; not necessarily more difficult, just different. Also, do you want all blinks...
  16. AnalogKid

    If I was a smart Electronicsy kind of person I would be interested in this!

    We need photos of the bad board to gauge the level of technology Volvo thinks is necessary for the task. A couple of opamps? a 100 pin microcontroller? both? ak
  17. AnalogKid

    Schematic Help

    Slightly off topic, but this is a source of confusion regarding the CD4017. The 4017 has 10 outputs. Usually these can be labeled Q0 - Q9, or Q1 - Q10, but not both (Q0 - Q10). The original RCA datasheet (now owned by Texas Instruments) labels the outputs "0" through "9" - *with the quotation...
  18. AnalogKid

    Schematic Help

    There is nothing wrong with the single-resistor approach; it is a common thing with 4017 LED circuits because of the decoded outputs. You just have to remember that the "off" outputs are a MOSFET switch to GND, not an open circuit. ak
  19. AnalogKid

    Schematic Help

    Not so. Referring to the schematic in post #5 - LED1 and LED6 are direct-connected to CMOS outputs. When counter output 3 (for example) is high, outputs 0 and 5 are low. The current path is from output 3 through D3 and LED3, to the cathodes of LED1 and LED6. Because R1 lets these cathodes...
  20. AnalogKid

    Schematic Help

    That is close to what I described, but . . . It places a reverse voltage across the two outside LEDs when any of the four inside LEDs are on. Not a problem when running on 5 V, but at 9 V and above there can be enough reverse voltage to cause the outside LEDs to go into reverse breakdown. In...
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