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  1. Alec_t

    Any ideas - Rotary momentary switch?

    I'd bet not momentary. If it were me I'd probably find a way to attach a spring to bias it to the centre position :D.
  2. Alec_t

    Auto reversing polarity after a few milliseconds (for solenoid control)

    My post 16 circuit relies on the output switch of the sensor being a push-pull type with the ability to pull down to ground. If, instead, the switch is a normally-open high-side-only type, then that circuit won't work and something along the following lines would be an option :-
  3. Alec_t

    Question about hall effect / floating signal

    By using the terms NC and NO I may have implied the switch had bias. That wasn't the intention. If the switch is manually controlled then NC and NO are interchangeable fo this application.
  4. Alec_t

    Any ideas - Rotary momentary switch?

    Is one of these too big?
  5. Alec_t

    Question about hall effect / floating signal

    Sounds right.
  6. Alec_t

    Question about hall effect / floating signal

    A SPDT switch, with common as the PCB input, NC going to the sensor and NO going to one or other power rail (depending on what your PCB will accept as 'zero' flow?
  7. Alec_t

    Auto reversing polarity after a few milliseconds (for solenoid control)

    From scratching around on the web it seems the power requirement for a similar valve is ~2.2W, implying a coil resistance of ~15Ω (but unknown inductance). The touch sensor spec says the output switch provides an output voltage equal to the supply voltage at up to 10A and can be configured as a...
  8. Alec_t

    LM13700 voltage controlled LP filter derivation

    Without analysing the circuit in detail I would expect the Darlington to give a DC offset of Vo relative to the cap voltage but not to affect the filter's AC frequency response. By Vc I assume you mean the cap voltage, not the control voltage?
  9. Alec_t

    How can i add a trigger to this circuit to make it not electrocute the user?

    Depends on how sensitive the LEDs are and how bright you want them to be. A CD4017 can source only a few mA. A 74HC4017 can sink a higher current. Which one are you using?
  10. Alec_t

    How can i add a trigger to this circuit to make it not electrocute the user?

    Why do you think a 9V circuit will electrocute the user? Btw, the LEDs should have current-limiting series resistors.
  11. Alec_t

    Op-amp Current Source Analysis

    To get 500mA out you will therefore need Vin=1000V :eek:. Your opamps ain't gonna like that :D.
  12. Alec_t

    LM4871 amplifier circuit not working, please help!

    It's not shutting down because, as per the datasheet "the LM4871's micropower shutdown mode (I Q = 0.6µA,typ) is activated when V DD is applied to the SHUTDOWN pin."
  13. Alec_t

    12V DC Motor (RS-550PC-8516) had some problem

    Then get the store to replace the motor for free.
  14. Alec_t

    Auto reversing polarity after a few milliseconds (for solenoid control)

    The valve is described as a magnetic latching type, which suggests its function is like that of a single-coil latching relay. Such relays require energisation pulses of ~10mS, the 'reset' current being the reverse of the 'set' current. Because the valve armature inertia is greater than that of...
  15. Alec_t

    Help with connecting&controlling THK kr20 Linear Actuator

    Oddly, the manufacturer's web-site has loads of info on mechanical details of their actuators but no info (at least, none that I could find) on their electrical connections/power requirements!
  16. Alec_t

    Semi Automatic water overflow controller

    I would suggest adding a pull-down resistor of ~100k between Q1 base and ground to ensure the base is never 'floating' at an ill-defined voltage. Q2 could benefit from a ~100k pull-up resistor to the +ve supply to prevent possible leakage currents from causing spurious setting of the latch.
  17. Alec_t

    help to calculate frequency of CD40106BC schmitt trigger square oscillator

    For a non-crystal CMOS oscillator the frequency will drift to some extent with temperature and with supply voltage, which is not ideal for some applications.
  18. Alec_t

    help to calculate frequency of CD40106BC schmitt trigger square oscillator

    The datasheet should tell you. For CMOS, Vt+ and Vt- are ratiometric with respect to Vdd. Vt+ is about 65% of Vdd and Vt- is about 35% of Vdd. Your mileage may vary. For TTL, Vt+ and Vt- are about 1.6V and 0.8V respectively.
  19. Alec_t

    How to control the speed of a 24vdc pump from circulating water temperature?

    Have you asked the makers of your particular pipe stat? They should know what the DC contact ratings are.
  20. Alec_t

    Can AC/DC be placed into a D Flip Flop?

    o_O I've no idea what you're asking. AC, with suitable conditioning (e.g rectification, thresholding, DC biasing), can be used to generate a signal suitable for the data or clock input of a flip-flop.
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