Search results

Search Forums New Posts
  1. Alec_t

    Power supply help

    Sounds like a thermal problem. Perhaps the power transistors are no longer making good thermal contact with their heatsinks? Dry joint at a power transistor leg?
  2. Alec_t

    How to test dishwasher thermostats

    Can you safely improvise a clamp and thermal coupling for the stat, to see if the machine then works ok?
  3. Alec_t

    How to test dishwasher thermostats

    It should be in good thermal contact with the metal plate. Was it just held with adhesive originally, or is there something to clamp it in place?
  4. Alec_t

    Measuring an IC's input resistance

    Because of slight mis-matching of transistors within the opamp in the IC. No manufacturing process is perfect.
  5. Alec_t

    Measuring an IC's input resistance

    Over the full operating temperature range the input offset voltage (a random-among-devices error voltage) might be anywhere between -15mV and +15mV according to the datasheet. The App Note's reference to 5mV looks wrong to me. I think the company was trying to tell you that it is preferred to...
  6. Alec_t

    Pump alarm and shut off system

    Does the float switch sense high or low level or both?
  7. Alec_t

    Trumps solar wall, forget politics we should just build the thing

    I predict there'll being lots of pairs of alligator clips attached to the solar array, with cables sneaking back over the Mexican border :D.
  8. Alec_t

    Measuring an IC's input resistance

    The HEN input is a logic-level Schmitt-trigger input. It typically sources 200uA for logic low and sinks a maximum 1uA for logic high. It can be driven directly by an MCU.
  9. Alec_t

    G24 electric lightbulb sockets

    That is obviously dangerous and indicates a poor connection internally. I hate just-push-the-wire-in type connectors, because contact is (usually) essentially made at only two diametrically-opposed points of the wire's circumference, whereas with a screw-down type connector (a) the screw exerts...
  10. Alec_t

    Replacing light bulbs with LED's for illuminating a radio's scale

    If you were to use amber/yellow/green LEDs instead of white their Vf would be lower so you would have more 'headroom' to define their current better with a dropper resistor, assuming the LED arrays are as in post #8.
  11. Alec_t

    Replacing light bulbs with LED's for illuminating a radio's scale

    So, the dial is edge-lit. The LED effort shown looks to have 2 LEDs at each end of the dial. More LEDs would clearly give a better spread of light. If it were me I'd try probably 6 per end.
  12. Alec_t

    G24 electric lightbulb sockets

    Are your sockets the quick-connect type, such as this ? If so, the wires are push-fit. They might pull out with considerable force, or you might be able to use a narrow-bladed screwdriver or similar tool to release the wire grip. As a last resort the wire would have to be cut off.
  13. Alec_t

    Samsung TV does not like free air signals

    If you have a clear view of the transmitter tower perhaps you have excessive signal at the antenna input. I've never heard of this causing problems, but perhaps the input stage is saturating/overloading? Do you get reception with no antenna at all?
  14. Alec_t

    Replacing light bulbs with LED's for illuminating a radio's scale

    A problem with LEDs is that they are very directional compared to incandescent bulbs. Each bulb may therefore need to be replaced by several LEDs aimed in different directions to get enough light spread. Alternatively a single LED could be behind a diffuser; but this would reduce the brightness...
  15. Alec_t

    How to interface condenser MIC output converted to Infrared transmitter output

    You will have to program the voice recognition software to give you a respective distinctive output signal for each word/command you want to recognise. You then use those signals as inputs to software routines which generate respective output pulse sequences which get transmitted by the IR...
  16. Alec_t

    Problems with MAC version of LTSpice 1V..

    Did you remember the "." before "tran"? LTspice uses the "." to signify commands.
  17. Alec_t

    How to interface condenser MIC output converted to Infrared transmitter output

    Which part do you need explaining?
  18. Alec_t

    Amplificator Audio, with LM741

    Yes? What about it? Welcome to EP!
  19. Alec_t

    Alternative Transistors for LM317 High Current Voltage Regulator Circuit

    A good way to search for alternative transistors is to use the parametric search facility on the web-sites of major distributors such as Digikey, Farnell, etc.
  20. Alec_t

    How to interface condenser MIC output converted to Infrared transmitter output

    Welcome to EP! It's certainly possible, but not straightforward. For voice control you will obviously need a microprocessor with voice recognition software able to A/D convert the microphone signal (which will need amplification and perhaps analogue filtering before the A/D conversion to avoid...
Top