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  1. kellys_eye

    OP-amp help

    Some 'problems' with your schematic - first the 'input signal' to the shaft speed sensor. You have to determine what this is and I suspect it will be a simple DC supply voltage (either 12V or 5V). The signal is not 'AC' - it is a simple squarewave with a reference voltage of zero (ground) -...
  2. kellys_eye

    OP-amp help

    Yes Bob, and the comparator would work like a buffer with a variable sensitivity input depending on the comparison voltage level set. The output would be close to the supply - as good as the comparator can manage wich will be no worse than a volt or so under the supply voltage - but I suspect...
  3. kellys_eye

    Wiring A Remote

    Power the board from 12V wired to DC12V (+ and -). Connect two wires, one from COM and one from NO. These will connect across your normal 'kill' switch wiring on the kart. Power it up. Press the remote and check for proper 'death'..... Then notify the authorities as appropriate...
  4. kellys_eye

    System resource usage....

    Well I followed those instructions and found that browser.remote.autostart.2 was what I needed to set to 'false' - but although it's stopped the second incidence of firefox running I now see that the resources used has increased :rolleyes: in 'compensation'???? It now shows 350Mb of resources...
  5. kellys_eye

    Stepper motor control

    Ardunio's own website isn't too bad a place to start: https://www.arduino.cc/ and you'll need to go there to download the IDE (programming environment) anyway. Arduino uses a lot of 'libraries' - code packages for specific purposes - and one such library (or 'sketch' as they are known) is...
  6. kellys_eye

    Thermoelectric Roof Generator: Need some help with my project.

    Yes, but they have different specifications regarding efficiency and voltage output/temperature profiles etc. If you want to just prove the principle then 'any' will do but be aware that these devices aren't exactly cheap so the power generating capabilities, in terms of cost-efficiency, will...
  7. kellys_eye

    Stepper motor control issue.

    It's undoubtedly a polarity issue - given the number of combinations of connection it could take a while....! Start by identifying the individual windings. Then parallel two windings on the same phase and try spinning the shaft with your fingers. Reverse the connections and try spinning the...
  8. kellys_eye

    Stepper motor control

    The principle is straightforward in that you know the distance travelled in one 'step' of the motor and that a single pulse makes the motor 'jump' that far therefore 'x' pulses get it to the specified position. A circuit to produce the pulse string(s) to move it where it's required and the same...
  9. kellys_eye

    Stepper motor control issue.

    That's not a diagram..... that's a list of the connections. If you haven't got the 'polarity' of the windings correct then you get problems. Do you have the datasheet for the specific stepper motor you're using?
  10. kellys_eye

    OP-amp help

    I don't think there's anything wrong with what the OP wants to do. A simple comparator circuit would probably do Vin would be the signal from your 'sensor' and the two 10k resistors could be replaced with a potentiometer to 'set' the trigger level.
  11. kellys_eye

    Stepper motor control issue.

    Show a diagram of the connections being used.
  12. kellys_eye

    System resource usage....

    The screen capture below is for FF open on just this EP site. I did find a whole load of add-on extensions that were running and have deleted them (some put on with recent software downloads - despite my clicking the 'no thanks' buttons.... grrrrrrr). The resource use is now down to...
  13. kellys_eye

    System resource usage....

    I'm running WIndows 7 on an old Dell laptop (Inspiron 1525) and it generally runs well enough but... ...looking at the system resources in Task Manager I see Firefox is running two instances (even with just one page open), one instance using some 400Mb or resource and the other using some...
  14. kellys_eye

    OP-amp help

    Have you used an ODB2 code reader to discover what the 'check engine' light is actually on for? The reader can be bought very cheaply these days and can also be used to reset the check engine light - this needs to be done after any fault has occurred anyway and the light may not be on for the...
  15. kellys_eye

    Power bank with bluetooth speaker - power draw issues.

    The device is a 3W amplifier with 90% plus efficiency so at maximum power it will draw around 600mA maximum (and probably only at peak signal levels). The amplifiers 'standby' current (known as the quiescent current) is some 10-15mA which should be more than enough to keep a power bank output...
  16. kellys_eye

    Pioneer CT-450 Tape Deck Repair

    So what's your question?
  17. kellys_eye

    Pacific 3404 Intercom

    You should be able to trace the copper tracks on the printed circuit board from the 'door open' button to the appropriate terminals.
  18. kellys_eye

    Which Component is This ? Inductor or Resistor?

    Looks (to me) like a 6.8Ω, 5% with a temperature coefficient band (5th). Gold is the multiplier, in this case x0.1 (IIRC)???
  19. kellys_eye

    Is this dc adapter safe to plug into my keyboard instrument

    Centre-negative is a known 'b*tch' in the industry - often only used where the socket is 'switched' and allows for change-over from internal batteries to external DC source - just as you have! You could do a quick check by snipping the wires to the plug (leave a few inches of cable so you can...
  20. kellys_eye

    TV lift board replacement

    U4 will have 12V, zero volts and 5V on the pins (not sure which order but providing you measure those voltages then the regulator can be considered 'ok'. With no load connected there shouldn't be much in the way of power dissipation in that device. You could snip (temporarily) the +5V link to...
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