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  1. Alec_t

    Op Amp with a/c output

    Have a read of this. If your car is old-ish I suspect your sensor is a variable reluctance type, rather than a Hall type, in which case it generates an AC signal but is passive (doesn't have a supply voltage provided by the ECU). What year/model is the car? Does your car service manual identify...
  2. Alec_t

    Op Amp with a/c output

    I'm puzzled as to how the output can be greater than the input. How many wires connect to the sensor? Presumably one wire is a supply input, another wire is the output and the sensor case is a ground connection?
  3. Alec_t

    Ring doorbell mains power

    Do you have a link to the datasheet/spec of the doorbell itself; particularly the input voltage and current requirements? Having to use a 24V transformer and a chunky resistor seems wasteful if a lower voltage supply will suffice.
  4. Alec_t

    Ring doorbell mains power

    Sounds an expensive set-up :eek:. Coincidentally, last week I decided to convert my doorbell from battery to mains, as I was fed up with the frequent/expensive battery replacements. My bell is a wireless one (cost around £7), the receiver requiring 3 'C'-size alkaline cells originally. I put a...
  5. Alec_t

    Op Amp with a/c output

    Can you post a pic of or a link to that section of the manual? It would help to understand the calibration procedure and might give a clue as to how best to amplify the sensor's 1.5VAC and inject a higher voltage.
  6. Alec_t

    Ultrasonic Transducer Driver adjust frequency

    If the inductor is part of the frequency-determining network then changing that would alter the frequency.
  7. Alec_t

    Replacing upper board with pot. for treadmill motor speed control.

    The original control board ensures the motor speed ramps up from zero at power-up as a safety feature. Do you want/need to replicate that feature?
  8. Alec_t

    Finishing touches on motion alarm

    Correct (apart from the base should be going to the PIR via the resistor that Dave suggested).
  9. Alec_t

    Finishing touches on motion alarm

    As well as the base resistor that Dave suggested, try connecting a 10k resistor between the transistor base and ground, to ensure the transistor switches off. (It's possible the PIR output is allowing the base to 'float' when the PIR is un-triggered).
  10. Alec_t

    Hydraulic Generators

    This would seem to be one approach :- If you use the pulse signal to trigger a fixed-width pulse monostable you'd get a FM signal with a speed-proportional duty cycle. The partly-smoothed inverse of that could drive the valve directly. Pulsing of the valve is advantageous (as a well-known...
  11. Alec_t

    Hydraulic Generators

    Sounds as though you need to provide a signal proportional to motor speed, for use in a control loop to vary the valve position. Is the 600Hz signal a PWM one, with pulse width related to motor speed?
  12. Alec_t

    ohms/Fuel Gauge and Sender

    Welcome to EP! Unfortunately it's not as simple as just fitting a resistor. Assuming the higher the fuel level the higher the sender resistance, then if you were to connect 60Ω in series with the 30Ω sender the total resistance would be 90Ω and a full tank would read correctly on the gauge...
  13. Alec_t

    12v receptacle

    Indeed. But then it wouldn't fit a standard 2-prong receptacle, which is what your question is about.
  14. Alec_t

    Drive A 5w Led

    What heat sink did you use? It's not clear from the write-up if the 700mA rating for the LED is for some specific set of conditions, e.g. a brief burst of current, continuous current, forced-cooling of the LED, ....... Personally, I would never drive a LED at the stated maximum current...
  15. Alec_t

    12 V motor loss of power

    If the (4-pole 3-way?) rotary switch is the forward/stop/reverse one, then it looks like the full motor current goes through the contacts on that switch. Use some switch cleaner on the contacts and see if that improves things.
  16. Alec_t

    simple led question

    Welcome to EP! A 5mm LED is not necessarily brighter, or more current-hungry, than a 3mm LED, so depending on your aims it may not be necessary to change the resistor value. I'd try the existing resistor.
  17. Alec_t

    Touch activated circuits

    You can easily simulate bouncing in LTspice. Why not in Yenka?
  18. Alec_t

    Lost Electricity

    Welcome to EP! Your pics don't show up. Post them here using the 'Upload a file' button.
  19. Alec_t

    Drill's battery not working.

    Could also point to the 'memory effect', for which NiCd cells are well known.
  20. Alec_t

    Thermoelectric Roof Generator: Need some help with my project.

    I imagine that in the Phillipines getting a surface hot (30°C) is no problem, but cooling an adjacent surface down might be. Presumably you're intending to use a Peltier device for this project?
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