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  1. Alec_t

    why connect a jfet gate to source?

    It biases the transistor so as to make it a fixed current source.
  2. Alec_t

    sunbeam electric blanket no heat

    The electrolytic capacitor, at top centre of pic _014, looks to be bulging at the top? The component in the bottom left of that pic seems to be a wire-ended fuse. If so, check its continuity with your meter.
  3. Alec_t

    precision voltage regulator adjustable

    In that case the PWM approach, with a precision potential divider, looks feasible; providing whatever the divider drives doesn't load it down beyond the tolerance.
  4. Alec_t

    need help with usb powered ultrasonic humidifier

    I'm betting the screw heads are below the board and the screw shanks extend up into those two lugs on the piezo. Can you post some sharply focussed pics (if necessary have the camera at its minimum focal distance then use a graphics editor to zoom in on the relevant bit of the image)?
  5. Alec_t

    precision voltage regulator adjustable

    What % tolerance is acceptable? What resolution is required within the 5-10mV range? What load will the mV source have to drive?
  6. Alec_t

    OK To Reverse One of Two Batteries To Prevent Leakage?

    Before reversing a battery, check that it won't then exert undue pressure anywhere in the battery compartment. The lid of my camera battery compartment is shaped such that reversing a cell would prevent closure of the lid without distortion.
  7. Alec_t

    Speakers + headphones at the same time

    Surround sound has at least four speakers. How do you propose squashing four audio channels into two earphones?
  8. Alec_t

    thrustmaster t300rs wheel dead no power

    Welcome to EP! Looks to me like the negative terminal of that big 2220uF cap hanging off the board has a dry joint with the board, with charring around it and the adjacent black connecting wire. Also, the big electrolytic (C88?) at bottom left seems to have leaked/cooked (or is that just shadow?).
  9. Alec_t

    Why don't I get a Sine wave?

    With your post #1 circuit, if you increase the time constant R7C2 to at least ten times the period of the triangular wave you should see an approximation of a sine-wave at the output, albeit of much lower amplitude than the triangular wave. The greater the time constant the better the...
  10. Alec_t

    OK To Reverse One of Two Batteries To Prevent Leakage?

    :confused: I don't see any saving of time/labour if you have to reverse the battery (cell) every time you want to use the camera.
  11. Alec_t

    Toyota ECM repair - SMD capacitor ID

    Is C120 in parallel with C107 across power rails (fat tracks)? If so I'd guess it's 100nF or thereabouts.
  12. Alec_t

    Looking for PCB design information

    Have you read this?
  13. Alec_t

    Use for old circuit boards

    Offer them to your local school/college for coversion to 'works of art'.
  14. Alec_t

    78M12 linear voltage regulator alternative

    Some sites which allow parametric searching have the type of package as a search parameter. A bit of googling should identify one or two types which meet your size criteria.
  15. Alec_t

    78M12 linear voltage regulator alternative

    The 78M12 comes in various packages. Which one do you mean? Whichever it is, I doubt you'll find any IC which can dissipate the same power in only 10% of the size :(.
  16. Alec_t

    Adding an external 240v garden light

    :confused: Your second pic apparently shows a 2-gang switch, not a twin socket. Two-wire lighting wiring cannot be legally/safely used for supplying a twin power socket.
  17. Alec_t

    Light Intensity Level Switch

    Assuming an inverse square law for irradiance as a function of distance, that implies a 16/9 variation in the measured light level which will have to be allowed for. Light beam shape/focussing would determine how close to an inverse square law the function actually was. How will distance change...
  18. Alec_t

    ECG front end simulation

    Use a pulse source of a few uV amplitude.
  19. Alec_t

    Adding an external 240v garden light

    Additional wiring in the wall/conduit to the outside light will be required. Since this project involves an outside light and is post 2005, it's my understanding that this work will have to be done by a 'competent person' in accordance with Part P of the Building Regulations to be legal.
  20. Alec_t

    Light Intensity Level Switch

    Is the device a fixed distance from the light source?
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