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  1. AnalogKid

    Locking cat door, really need some help...

    See the link in post #10. It has no internal protection or switches of any kind, so you have to drive it with a timed power pulse that lets the motor stall for only a short time. ak
  2. AnalogKid

    Power Dissipation in a simple circuit

    First, post a schematic. There is no amount of text description that will tell us as much about the circuit and the components as will a schematic . Identify each component with a reference designator, like "R1" for a resistor. ak
  3. AnalogKid

    Help with ttl power-on reset pulse

    Here is the same circuit without the 555. The added resistor R3 adds hysteresis to the R-C input to eliminate possible noise bursts at the output. It does not affect logic action caused by the pin 11 input. ak
  4. AnalogKid

    Remote controlled starting grid lights circuit help

    Photo / datasheet / website link ? ak
  5. AnalogKid

    Remote controlled starting grid lights circuit help

    Those are the right parts. Turning everything on and off with a physical switch means the receiver is not on 24/7, probably a good thing. AND, it makes the controls easier: Power on - reset to all lights on. Wait. Button #1 - run through the sequence, stop with just light #4 (green) on...
  6. AnalogKid

    Locking cat door, really need some help...

    Surplus market car door lock mechanism. These are based on a reversible DC motor that moves a plunger in or out with a gear mechanism. The motor sits there unpowered no matter which location the plunger is in. If you find one of those and again put a tab or bolt on the armature to block the...
  7. AnalogKid

    Piezo To Detect Sound

    1 Hz-ish
  8. AnalogKid

    Locking cat door, really need some help...

    Easy part: A small DC solenoid with a spring built-in to keep the plunger extended when off. Power comes from a wall wart plugged into the switched outlet strip. Not so easy: To the end of the plunger attach a metal strip (or, if it has a hole through it as many do, a long bolt secured by a...
  9. AnalogKid

    Locking cat door, really need some help...

    Not my point. If the off the shelf lock can lock in one direction only, that isn't a problem because you don't care about locking them in, just out. If you mean it permits door movement in one direction only, that's something different. ak
  10. AnalogKid

    Locking cat door, really need some help...

    Without photos or information on the door and the off the shelf locks, it's kinda hard to say. But. The door swings in both directions, but the cats *enter* from one direction only ... ak
  11. AnalogKid

    Remote controlled starting grid lights circuit help

    If I understand this correctly, it is a 5 step sequence that sits in step 1 for an unknown time, then moves through steps 2-5 at a fixed rate when triggered, ending by sitting in step 5 for an unknown time: Button #1 turns on everything, system starts at step #1: 1. 1+2+3+4 System sits in step...
  12. AnalogKid

    Need help designing a resistor sequencer.

    There are two versions of a 555 astable oscillator circuit, and yours is the classic. Here is an excellent calculator to help you predict its operation. http://www.ohmslawcalculator.com/555-astable-calculator I don't think you've stated what the effect is that you are trying to achieve, or...
  13. AnalogKid

    Flip Flop Charging - Can this be done?

    You are correct about the transistor designation; NPN was a typo. However, current still cannot go through it backwards. 1. Q1 is on and C2 is charging - C2 is charging though a 100K resistor. As I said, assuming a 0.1F cap (since there is no value on the schematic, I chose the smallest one...
  14. AnalogKid

    Flip Flop Charging - Can this be done?

    Bullet items 1, 2, 4, 5, 7, and 8 are incorrect, have serious errors, or do not describe the components in the schematic. For example: 1. Q1 is on and C2 is charging - for a *very* long time. Even with a small supercap such as 0.1 F, the time constant is 2.78 hours 2. Q2 is off and energy...
  15. AnalogKid

    Need help designing a resistor sequencer.

    If you are talking about testing just the three chips and three switched resistors, then yes, an ohmmeter should show the effects of the mux switches. In the schematic in post #3, connect the meter to the two blue wires. ak
  16. AnalogKid

    Need help designing a resistor sequencer.

    In round numbers, a typical small red or green LED needs about 2 V or pulsed or steady-state DC across it to light, and the brightness depends on the current through it, usually up to around 20 mA. Nowhere in the signal path of the pedal are there those voltages or currents. R10 is a negative...
  17. AnalogKid

    Need help designing a resistor sequencer.

    You refer to a resistor R10, but that is not in your image. If that is a part in the original pedal circuit, can you post that schematic? Also, there is nothing obviously wrong with the circuit you show, but it will not work with LEDs substituted for R1-R3 for several reasons. Do you want to...
  18. AnalogKid

    LM317 and LM741 as a current source

    If the symbol marked +A- is a current meter, the circuit cannot work and the load is connected to the wrong place. ak
  19. AnalogKid

    Help with basic counter circuit

    4 bits is only enough signals to drive one digit, so your question about a 4-digit display is not clear. It would show only one digit. ak
  20. AnalogKid

    Help with basic counter circuit

    In the 2-digit counter schematic, the switch is not in the best place. But that is discussed in the response. Other people say there are problems but give no details, so ignore them. To your original question, which 4-digit display? Some are internally connected for a multiplex drive. The...
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