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  1. AnalogKid

    Unwanted powered circuit

    "A" charger module? What about the other one? ak
  2. AnalogKid

    Unwanted powered circuit

    IF the charger modules are a variation of a non-isolated buck regulator, then there is a clear power path with the switch open. But ... Without knowing anything about the charger module, your question is meaningless and impossible to answer. Please post information about the modules...
  3. AnalogKid

    1.5 volt bulb won't light in my circuit newbie

    Only if you include the current through the ground or adjust pin. For some parts that is uA. ak
  4. AnalogKid

    1.5 volt bulb won't light in my circuit newbie

    That 1 ohm resistance measurement is the clue. Incandescent bulbs are very hungry. ak
  5. AnalogKid

    1.5 volt bulb won't light in my circuit newbie

    Check your meter with the leads touching each other; a part of that 0.8 might be test equipment error. ak
  6. AnalogKid

    1.5 volt bulb won't light in my circuit newbie

    A.l.w.a.y.s post a schematic. This is one of the things that is not intuitively obvious to a beginner, because it involves the consequences of how a battery actually functions, and it appears to the rest of the circuit. My GUESS is that you are trying to step down the 9 V to 1.5 V with a...
  7. AnalogKid

    Design 3-step sequence circuit.

    We help those who help themselves. Please post your schematic. To aid the discussion, be sure to have a reference designator for each component (R1, C1, etc.). ak
  8. AnalogKid

    traffic light australian with 2 555 timers

    That change will assure that the U2 period is not longer than the U1 period no matter how the pots are adjusted. But that does not fit the description in post #1. Have you verified that the two 555s oscillate correctly when they are *not* interconnected? Without that, no changes will work. ak
  9. AnalogKid

    traffic light australian with 2 555 timers

    Disconnect U2 pin 8. this removes power from U2 and isolates it from U1. Verify that the U1 part is working correctly: Disconnect the top of VR1 from U1 pin 3. Add a 10K resistor in series between U1 pin 3 and the top of VR1. Adjusting VR1 should vary the red LED timing from about 12 seconds...
  10. AnalogKid

    traffic light australian with 2 555 timers

    No, I'm saying your problems probably are a wiring error. ak
  11. AnalogKid

    traffic light australian with 2 555 timers

    I'm saying the schematic is missing important (but not necessarily critical) parts. This is a sign of either an inexperienced designer or one who just forgot them because adding them to the build is automatic for him. A critical assumption in the design of all integrated circuits is the...
  12. AnalogKid

    traffic light australian with 2 555 timers

    I fully support your education process. When I was in high school (1960's), all I could get were hand-me-down issues of Popular Electronics. Now, the universe is available, including PDF files of all of the old electronics magazines.
  13. AnalogKid

    traffic light australian with 2 555 timers

    Looks like this one is all on you. The sch is not how I would do it, it does use the Discharge output in a non-standard way to get two switched outputs from one part; not a bad trick. The only thing missing is decoupling capacitors across the 555 power pins. This is a bit of a problem because...
  14. AnalogKid

    traffic light australian with 2 555 timers

    Not all of the components have reference designators, so we need to add some: Left 555: U1 Right 555: U2 Red LED: D1 Yellow LED: D2 Green LED: D3 With VR1 in the middle of its range, U1 has an output period of approx. 11 seconds. That means D1 is on for 5.5 seconds and off for 5.5...
  15. AnalogKid

    traffic light australian with 2 555 timers

    "work" is a purely subjective term. If you don't know what the sequence is supposed to be, how can we evaluate why it is not happening? Let's back up. What is this for? What are you building? Model train set? Science Fair project? Architectural demo? ??? ak
  16. AnalogKid

    traffic light australian with 2 555 timers

    Your question doesn't say *anything* about what it is you are trying to achieve. Please describe the timing sequence in a text table like this: Red only: x seconds Red and green: x seconds Green only : x seconds Green and yellow: x seconds Yellow only: x seconds repeat Or something like...
  17. AnalogKid

    newbe help with schematic to breadboard

    Please post your schematic first. What you've figured out will change what I post. ak
  18. AnalogKid

    plastics electronics crack

    Your question has zero useful information. What parts? What cracks? Photos? ak
  19. AnalogKid

    newbe help with schematic to breadboard

    The circuit is based on the idea that each light period is a multiple of a basic "tick", the output period of the 555. From your description, if you set the tick to 15 seconds, then the sequence is this: Red - 4 ticks Green - 4 ticks Yellow - 1 tick repeat A total of 9 ticks fits well within...
  20. AnalogKid

    ULN2803A

    Agree with HK. Tack a 0.1 uF ceramic cap directly the ULN's GND and COM pins with the shortest possible leads, and see if the transient waveform is altered (or eliminated). If (hopefully) attenuated, tack on another one to see if things improve more. If yes, then you have a solution path to...
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