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  1. Alec_t

    How difficult to have a microphone made

    Do you mean it has to be small enough to fit inside the phone, or simply have a USB plug for plugging into the phone's USB port?
  2. Alec_t

    NiMH battery pack mystery

    Measure the individual cell voltages actually at their terminals while in the holder and maximum current is being drawn by your load. Does the sum of those voltages equal the single voltage across the cell pack ends? If not, the interconnections within the holder have a high resistance.
  3. Alec_t

    Convert 1 phase to 3 phase by using an old washing machine

    But the wash-machine motor is only rated 195V 3A. So it's unlikely that control board would survive long even if you got it working.:(
  4. Alec_t

    Induction motor short circuit

    Welcome to EP! What was the resistance test voltage?
  5. Alec_t

    Hot Wire in Salt Water.

    Under stress you could be taking a breath very frequently. I doubt your compressor would survive long being switched on/off frequently. That said, a small sealed reed switch could perhaps be actuated by a magnet attached to the diaphragm and could then trigger a relay (or solid-state switch) at...
  6. Alec_t

    Ampere/voltagemeter

    For the post #10 circuit I don't see how. The digi-meter current-shunt -ve end and the meter -ve supply terminal are commoned at the D3/4 junction, the current-shunt +ve end is at the D1/2 junction, but where does the meter get its +ve supply? It can't come directly from V1 because that reverses...
  7. Alec_t

    Ampere/voltagemeter

    That works for measuring the motor voltage, but won't the commoned -ve pins preclude measuring motor current?
  8. Alec_t

    L298n connecting in parallel

    Bear in mind that the start-up (stall) current of a DC motor will usually be several times its normal running current.
  9. Alec_t

    Ampere/voltagemeter

    It is likely a 'sort of' average of the pulse waveform, but only when the motor is running in one particular direction.
  10. Alec_t

    Ampere/voltagemeter

    What speed controller do you have? If it's one that uses PWM then that may not play nicely with a digital meter.
  11. Alec_t

    Inverting a modulated signal (OOK).

    I replied over at AAC. The post #1 sim works ok as is with the default 'A' devices in LTspice (providing the AND gate is given a finite td parameter), so there could be a problem with the Multisim models or implementation.
  12. Alec_t

    NAD 3020A Amplifier Low Volume

    No direct connection between the electrolytic caps and ground visible in post #26.
  13. Alec_t

    NAD 3020A Amplifier Low Volume

    That's certainly an improvement on the post #26 version.
  14. Alec_t

    Help with Thermistor

    I would expect any visible thermistor to be a non-descript surface-mount device (SMD) component (such as this example), visually similar to a SMD capacitor or resistor. It might even be an internal component in a multi-pinned IC. However, thermistors are generally very reliable and my guess is...
  15. Alec_t

    NAD 3020A Amplifier Low Volume

    That's a useful pic. So the schematic shows ±30.5V, i.e 61V between the two power rails. If that's under the full working load and your measured 64V is under a lesser load then it's about right (32V per cap). However, there are no balancing resistors shown across the caps to help equalise the...
  16. Alec_t

    Help with Thermistor

    Why do you think there's a thermistor on any of those particular printheads?
  17. Alec_t

    NAD 3020A Amplifier Low Volume

    The only cap voltage ratings I've spotted so far in the thread are 35V (post #1) and 25V (post #19). Something doesn't smell right, given the DC output voltage readings.
  18. Alec_t

    How is current passing through the capacitor in the following schematic?

    Correct. Note that there is always a complete path via the two resistors connected to the ends of the capacitor.
  19. Alec_t

    Can't find the transformer I need so need to build my own

    I think you'd better have a fire extinguisher handy. Mains primaries normally have a LOT more turns than that. Im sure some other member here will have the figures/maths.
  20. Alec_t

    Solenoid Current Flow

    I'm sure someone here can do the maths, but I just let LTspice do it for me :- Unless the cap's ESR is unusually high the initial current (here, 5A for a coil with resistance 50Ω) is dominated by the coil's resistance. BTW, it's not wise to charge a 300V rated cap to anywhere near that voltage...
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