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  1. Alec_t

    Frequency generator

    If you want low distortion, particularly with the sine output, and a frequency range as wide as that the circuit won't be quick, cheap or easy unless you use a digital (microcontroller) approach. How much distortion can you tolerate? What voltage and current requirements do you have?
  2. Alec_t

    Sewing machine speed controller repair

    That is a tungsten (filament) lamp. The most likely component on that board to fail is the semiconductor device (arrowed) :-
  3. Alec_t

    Sewing machine speed controller repair

    Have you checked if any fuse present in the plug/cable/pedal is good?
  4. Alec_t

    Porcupine Transformer

    Did you thoroughly remove the enamel coating of the wire ends before doing the test?
  5. Alec_t

    Light sensor motor control

    That's good to know.
  6. Alec_t

    Light sensor motor control

    Oops. Ignore the suggested foot-switch connection in post #15. I misread your start/stop requirements. It occurs to me that if the operator keeps the foot-switch pressed the light sensor won't turn the motor off. You could overcome that by capacitively coupling the foot-switch to pin 2 :-
  7. Alec_t

    Light sensor motor control

    Providing R3 is at least ~2k, connect the foot-switch (it needs to be a normally-open momentary type) in series with a 1k resistor between pins 6 and 8. Did you try a pull-down resistor at C1 left end?
  8. Alec_t

    Light sensor motor control

    Perhaps your sensor has a pull-up transistor only. In the post #8 circuit try adding a resistor (say 10k) with one end connected between the sensor output and the cap, the other end grounded.
  9. Alec_t

    Three-phase inverter for Induction motor.

    Welcome to EP! You haven't shown the complete schematic, so it's impossible to say with any confidence where the fault might lie. As shown, for example, the LED cathodes are unconnected and there are no power supplies, so none of the IGBTs should be active.
  10. Alec_t

    Boiler thermocouple voltage monitor

    3mV/0.1Ω = 30mA. I'm surprised it can go as low as that before the solenoid drops out. We live and learn. Although 200mA in a single conductor should provide a strong enough magnetic field to be detected easily by a Hall effect sensor, the inner and outer conductors of the thermocouple (assumed...
  11. Alec_t

    Boiler thermocouple voltage monitor

    20mV/0.1Ω = 200mA. I doubt the valve will hold open with less than, say, 50mA. So if your ADC runs on 5V any resistor > 5V/50mA = 100Ω should be ok. A 1k resistor would limit any fault current to 5mA. But how will you get access to both conductors of the thermocouple? If yours is anything like...
  12. Alec_t

    Low DC voltage at wider distances for ESP32

    If you mean constant current drivers, then those would seem unsuitable for powering an ESP32 (which will draw varying current from a fixed voltage source).
  13. Alec_t

    Low DC voltage at wider distances for ESP32

    Couldn't you use a higher voltage power supply and have a 3.3V regulator at the ESP32 position?
  14. Alec_t

    I'm looking for an apartment in the Miami area in July 2019

    Googling 'holiday lets miami' gets lots of hits, including the one Minder mentions.
  15. Alec_t

    the twelve days of christmas?

    Sum of n numbers 1 to n = n*(n+1)/2. n=12, therefore sum = 12*13/2 = 78.
  16. Alec_t

    24VAC Step-up Transformer

    Welcome to EP! What is providing 28V? How much current does the lamp draw?
  17. Alec_t

    Do SMD resistors fail open after some time?

    Is it the resistor itself which fails, or an end joint?
  18. Alec_t

    Smoothing a charging current for a phone?

    I've never used one of those, but it looks promising. Whether or not it performs as advertised is another matter, but at only AU$1 surely it's worth a gamble?
  19. Alec_t

    Smoothing a charging current for a phone?

    Probably no phone coverage either :).
  20. Alec_t

    Question contact slot and contact conector snes

    Ask the manufacturer.
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