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  1. Alec_t

    Alarm Dilema

    Could damp air be causing enough leakage across the switch to turn the SCR on? Which SCR are you using?
  2. Alec_t

    Help with battery powered PC case fan

    A view not held by the younger generation, it seems ;) .
  3. Alec_t

    help designing triggering device for underwater camera

    Hope all goes well. We'll expect a few uploaded pics :).
  4. Alec_t

    help designing triggering device for underwater camera

    I think the technician was being over-cautious. Flexible wire the thickness of ordinary bell-wire should be ok for 100m. Its resistance would be less than 10 Ohms. Simulation with LTspice shows that even a 100 Ohm cable would trigger the camera reliably. Ruggedness and water-resistance of the...
  5. Alec_t

    Operating a DMX controller with a footpedal - help and guidance please !

    Plenty of low coil current relays available, such as this. (<20mA).
  6. Alec_t

    RT8059 step-down DC/DC converter - can't get it to be stable, annyone with experience?

    You'd be surprised what you can do with copper-clad board and simple hand tools, such as a drill, needle file, and a robust craft knife (or even a length of broken hacksaw blade). A Dremel or similar tool would be an advantage. Fortunately the recommended layout (Fig 3 of the datasheet) is...
  7. Alec_t

    12v camper thermostat and heater

    Have you done the maths to see if 200W is sufficient? The mass of air involved is ~6kg and will need ~6kJ (6kWsec) to heat it 1 degree C. With a 200W heater that would therefore take ~30sec; so 5 mins for a 10 degree rise (assuming no heat loss).. Do you know the thermal resistance of the...
  8. Alec_t

    Triangular wave generator simulation with LTSpice

    Yes, you've understood correctly. You can check for yourself by changing the value of R4 and seeing what happens to the voltage on the non-inverting input of the comparator.
  9. Alec_t

    Operating a DMX controller with a footpedal - help and guidance please !

    I suspect the added inductance and capacitance due to the long leads is the cause of the problem. Do you have access to an oscilloscope to see what scanning voltages are being applied to the buttons by the controller?
  10. Alec_t

    Trying to make a transistor cancel another transistor

    Since you have no current-limiting resistors it's surprising something didn't fry!
  11. Alec_t

    Trying to make a transistor cancel another transistor

    If I've understood you correctly you could arrange the second transistor so that when it turns on it shorts the base-emitter junction of the first transistor.
  12. Alec_t

    Triangular wave generator simulation with LTSpice

    The LT1122 is not a rail-to-rail output type. Its output rises only to ~7.5V. With the lower R4 value the feedback was excessive and prevented the non-inverting input of the comparator reaching the vref level.
  13. Alec_t

    Triangular wave generator simulation with LTSpice

    Increase R4 to at least 22k and your oscillator should run.
  14. Alec_t

    sound frequency resulting from coil windings

    Be aware that they are not rated for prolonged duty, IIRC.
  15. Alec_t

    sound frequency resulting from coil windings

    If the stainless steel is magnetic then a solenoid coil could vibrate it. If it's non-magnetic then a piezoelectric transducer could do the job.
  16. Alec_t

    Semi Automatic water overflow controller

    You could add a 'supply missing' switch in parallel with SW2.
  17. Alec_t

    hydrogen powered electrical motor

    I think you'd have to modify it a LOT! The motor shown is pretty feeble.
  18. Alec_t

    hydrogen powered electrical motor

    If by 'multirotor' you are referring to a rotary-wing aircraft then it's doubtful. However, a Raptor E1 fixed-wing drone powered by a hydrogen fuel cell has been flown.
  19. Alec_t

    Can an infrared thermometer cause damage to components?

    Coincidence. The infrared is received by the thermometer; not transmitted to the DUT. The laser is low power and used only to show the DUT spot which is being measured. Welcome to EP!
  20. Alec_t

    Vintage doorbell issues

    To dissipate heat better? What is the supply voltage for the bell, and the coil resistance?
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