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  1. AnalogKid

    Modified pocket calculator

    1. Why 1000 digits? 2. Use your phone.
  2. AnalogKid

    replacing 4.7k pots with 5k on negative feedback op-amp circuit

    That is correct as a general statement, but without a schematic we don't know that the pot is in the feedback loop. ak
  3. AnalogKid

    replacing 4.7k pots with 5k on negative feedback op-amp circuit

    The tolerance on low cost pots is 10% or worse, so they probably were intended to be 5K all along. ak
  4. AnalogKid

    Generating a DC supply from the attached circuit

    About the same as in the US. Usually we have unswitched line and neutral coming into the switch box, and switched line and unswitched neutral going out to the light. The two neutrals are joined together inside the box with a wire nut. Yes. Ohm's Law. With the AC peak voltage and the...
  5. AnalogKid

    Generating a DC supply from the attached circuit

    That is not your normal dimmer circuit, and the 48-page description is excellent. I was going to point out the lack of a decoupling cap on the CD4025, but now it makes sense. Other circuits are in US patent 4649302 (from 1987), 5004969, and 7102902. Note that many FET-based dimmer circuits...
  6. AnalogKid

    Generating a DC supply from the attached circuit

    Yes, but the the 12 12K resistors will have to change and will get very hot. This circuit has several glaring errors. For example, when Q1 is turned on it shorts the AC LINE directly to GND. Post a larger schematic that is readable. Also, a link to wherever you got this one. Note that using...
  7. AnalogKid

    Remote controlled starting grid lights circuit help

    Capacitors C4, C5 are decoupling capacitors for the three ICs. They should be placed as close as possible to the power pins of each chip. Also, note that the schematic does not show these power pins. That's because most schematic software does not. Power and ground connections are assumed to...
  8. AnalogKid

    Can we use 5VDC LED in the AC line to show indication

    In place of a 10 W resistor you can use a 0.5 uF film capacitor rated for the AC voltage. But you still need either another LED or a 1N4007 diode in reverse parallel with the LED. And the downstream devices still will be dangerous when the fuse blows. ak
  9. AnalogKid

    Power Dissipation in a simple circuit

    What if you post a schematic so we can see what you are talking about. Hint - if you post this question on a third forum, they will ask for a schematic also. ak
  10. AnalogKid

    USA to uk convert

    That equals 66 degrees; I was pretty close for a SWAG. ak
  11. AnalogKid

    USA to uk convert

    Nope. You would be correct for a full sine wave, but then there is no power limiting. The TRIAC is delaying the point of turn-on (and current flow) until most of the half-sine has passed by. At the time a TRIAC comes on in this application, the instantaneous voltage is not at the peak of the...
  12. AnalogKid

    USA to uk convert

    I have both kinds, a heavy lump of iron rated for 25 W and a lightweight air-vented can rated for 1500 W. It is a TRIAC dimmer with a fixed phase angle - no way to accidentally turn it up to 100%. ak
  13. AnalogKid

    USA to uk convert

    I'm with Bob. For a 120 V device running on 120, a diode cuts the power in half. but for a 120 V device running on 240, the device is running at 4 x the normal power (E*squared* over R) without a diode, and 2x with. The lowest cost solution I can think of is a TRIAC lamp dimmer in series with...
  14. AnalogKid

    555 output to transformer failure

    I should have been more clear. The image in post #30 has the voltage across the 100K load resistor. Or is it the voltage from the top of the 100K resistor to the primary side system ground? Either way, what I'm asking for is a scope shot of the voltage across R2 only. I want to see the...
  15. AnalogKid

    555 output to transformer failure

    I think the output numbers look funny. Can your simulator show us the output waveform? Also, does it know how to deal with a floating voltage source (not referenced to the primary side ground)? ak
  16. AnalogKid

    Remote controlled starting grid lights circuit help

    It all comes down to the relay board. Roaming around on ebay it looks like there are two basic kinds, one with optocouplers on each control input, and one with a simple transistor driver on each input. The problem is that there is no documentation to get a good solid feel about hot to drive...
  17. AnalogKid

    Remote controlled starting grid lights circuit help

    If you can figure out how to smuggle Samuel Smith's Best Bitter...
  18. AnalogKid

    Guitar pedal that records noise and compresses it into an effect

    There are commercial guitar synthesizers on the market that have a sampling function. All I know about them is that they are out there somewhere. ak
  19. AnalogKid

    Remote controlled starting grid lights circuit help

    Full disclosure, almost everything on this schematic can be replaced by an 8-pin PIC. But enough about typing. Here is a first pass at a light tree timing circuit. U1 is a counter that steps through the timing pattern. U2C is the timing oscillator, current set to 2 Hz (-0.5 seconds per...
  20. AnalogKid

    Remote controlled starting grid lights circuit help

    Depends. What is your skill set for assembling a circuit on perf board or a proto socket board? The 2803 part is in a D package. That is one of the larger surface mount packages, and can be hand soldered without great difficulty. However, it won't work with a proto board or standard perf...
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