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  1. AnalogKid

    Momentary Switch to directional DC motor

    Well, I did not see that coming. Would have been nice if the OP had mentioned that the motor was so large. ak
  2. AnalogKid

    Momentary Switch to directional DC motor

    What are the voltage and current ratings for the motor? Also, can you post a link to the manufacturer or vendor's data page? ak
  3. AnalogKid

    Momentary Switch to directional DC motor

    The motor runs only when the button is pressed, and cannot change direction once it is up to speed. Direction change happens only during the first milliseconds when the button is pressed and the relay changes state. To change direction, the button must be released, removing all power from the...
  4. AnalogKid

    Momentary Switch to directional DC motor

    Here is a first pass at the approach I described above. Notes: 1. 100% of the motor startup and running currents go through the switch. The switch contacts should be rated for at least twice the motor startup current value. If this is a problem, then a smaller switch can drive a SPST relay...
  5. AnalogKid

    Momentary Switch to directional DC motor

    Not until next Monday or Tuesday. I'm traveling and can't do schematics on this device. What you want are a reversing function (like a DPDT relay) and a toggle flipflop function. A bistable impulse relay can do both...
  6. AnalogKid

    Momentary Switch to directional DC motor

    This can be done with a single DPDT impulse relay and a momentary switch that can handle the motor current. ak
  7. AnalogKid

    Do I understand what this does ?

    There are very low cost cycle timers on ebay with relay or FET outputs. ak
  8. AnalogKid

    Do I understand what this does ?

    AT $1.62 and free shipping, it is cheaper than buying just the power MOSFET. The 8-pin part is the FET, and the 6-pin part could be an LV logic part such as 1/2 of a CD4013. Or a 6-pin uC that does the switch debouncing in software. ak
  9. AnalogKid

    How to design a transistor circuit that controls low-power devices

    Seems odd to me that you would think that. One video does not a universe of experiences make. Solderless breadboards (proto-boards) have been around since at least the 70's, and all manner of things have been done with them. The better ones have a contact rating of 1 A. ak
  10. AnalogKid

    How to design a transistor circuit that controls low-power devices

    You are fine so far, but you are flirting with danger. And a misconception. Transistors are not perfectly repeatable. There is a lot of variation in performance from one piece to another. also, for gbest long-term reliability, you should run a transistor at less than 1/2 of its ratings. So...
  11. AnalogKid

    Early 1970's Fairchild Transistor Question

    In the beginning, transistors came in metal cans and (eventually) almost all part numbers started with 2N. Then came non-metallic critters with various company-specific designation indicating a "normal" part in a different package, such as EN (epoxy) and PN (plastic). Always check the...
  12. AnalogKid

    Two unrelated questions

    When applied correctly to properly prepared surfaces, thermal paste is a far better thermal conductor than the pads. It is also lower weight, but that is important only in a very small number of applications. The pads are much better at gap filling (and some are designed specifically for...
  13. AnalogKid

    Analog Circuit to Randomly Modulate Amplitude and Frequency

    As above, there a re several ways to amplitude modulate "any" signal, from a simple FET acting as a voltage-controlled resistor to a four-quadrant multiplier. And there are several ways to produce amplitude-limited and bandwidth-limited random voltages. But ... Varying the frequency of "any"...
  14. AnalogKid

    Need help for value of resistor

    In the discussion about how high the flyback voltage might get before the suppression diode "kicks in", something important has been left out, something that HK covered by inference. The risetime and size of the flyback spike are critically dependent on the turn-off time of the switch device...
  15. AnalogKid

    12V to 5V 3A converter

    Correct, a fuse on the input can have a rating lower than 3 A and still support the full output. The max. output power is 15 W. If the converter is 100% efficient, then the input current at 12 V is 1.25 A. But the converter is probably only 75% efficient at full load, so it needs 1.67 A of...
  16. AnalogKid

    Is there a 12VDC power regulator / timer?

    If by "device" you mean something you can purchase, I don't know of one. As a circuit it would be fairly simple. I like the CD4060 oscillator/divider as the basis for loooong timer circuits. It is at its most simple when the requirements are binary relationships, like one hour on in every 16...
  17. AnalogKid

    Allan Timer Circuit

    Connect it to *what*? If you don't provide any information we can work with, how can you expect an answer? What power sources do you have to run the device? What do you want to connect to the relays? What kind of signals do you have to control the timer? ak
  18. AnalogKid

    Operating mirror folding motors

    Your question is not at all clear. What do you mean by "operate directly"? Connecting green to orange and red to gray makes the motor turn in one direction. Connecting green to gray and red to orange makes the motor turn in the other direction. ak
  19. AnalogKid

    supply voltage

    Maybe in the 60's, but it's been the standard CMOS logic voltage range for over 50 years. ak
  20. AnalogKid

    supply voltage

    The normal operating voltage range is 3 V to 18 V. The absolute maximum ratings are the levels at which damage to the chip can occur. So at 2 V the chip is not warranted to work correctly, but it is warranted not to be destroyed. ak
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