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Recent content by ccurtis

  1. ccurtis

    Unusual potentiometer

    Is the volume control built using a single resistance element with fixed taps to the resistance element near each end, or are there separate resistance elements for the taps and a shared wiper. Of course, I'm only talking about one of the two gangs, here.
  2. ccurtis

    Unusual potentiometer

    Thanks, guys. That very helpful information! I had NO idea. So, Nigel, would you have soldered the wires that went to the two taps, each connected to the nearest respective endpoints of the 3-terminal pot? Or just leave the tap connections disconnected? Or a combination of those two...
  3. ccurtis

    Unusual potentiometer

    Can someone explain the potentiometer, R55, in the figure below. I only know about three terminal pots. It is ganged with an identical pot for the other audio channel and is the volume control for an OLD Grundig radio. I want to simulate the tone circuit but can't because I don't know the...
  4. ccurtis

    Light organ, human brightness versus loudness perception

    That's a very Interesting question. I'm working with LEDs driven with PWM current, whereby the light intensity is, largely, linearly proportional to PWM percentage, so the answer is not particularly relevant to those. In the old light organs the audio voltage drives a triac circuit and the...
  5. ccurtis

    Light organ, human brightness versus loudness perception

    Yes, ZZO. In light organs, a sound threshold must be established below which no light is output because there is always some ambient and circuit noise present. The peak of the music is detected and a line is calculated from the threshold to the peak level that determines the gain, before any...
  6. ccurtis

    HDC3020 and HDC3020 Humidity Sensors

    When considering performance I look to the datasheets because I certainly don't have the precision measurement equipment required for real-life experience. But, to add a fly to the ointment, there is a very similar deice, SHT35-DIS from Sensirion to consider also. The only real-life experience...
  7. ccurtis

    Light organ, human brightness versus loudness perception

    It may not be immediately apparent, but once the x^2 correction is applied, the result is a logarithmic response that is equivalent to the human hearing response, y=x^0.67, which is quite close to a square root response, y=x^0.5. If you plot y=x^0.67 (hearing) and y=x^0.33 (vision) as a graph...
  8. ccurtis

    Light organ, human brightness versus loudness perception

    In a light organ, the amplified signal from a microphone, or audio line output, is applied to a controller that subsequently drives the light intensity of a light source(s) for the purpose of adding a dimension of sight to the music listening experience. In most designs the goal is to have the...
  9. ccurtis

    Probability distribution of mail time of arrival

    The time of mail arrival does vary a lot. From my data so far, mail arrival spans 1:47p to 7:22p with two humps in the histogram; one huge hump in the interval from 1:47p to 2:54p and another small hump in the interval 4:01p to 5:08p. There is also an interesting gap from 3:00p to 4:00p when...
  10. ccurtis

    Probability distribution of mail time of arrival

    Hello, Just for fun I have collected data, 40 points so far, of the daily time of arrival of snail mail to my house. I applied normal distribution stats to the data to get an objective view of the probability of receiving mail within certain time intervals. But, there is an issue. The data...
  11. ccurtis

    Continuous, very small reverse voltage on electrolytic capacitor

    Thanks, folks. Good stuff. I opted to lift the voltage on the + (input) side of the cap a few millivolts to counteract the reverse voltage, just to be sure.
  12. ccurtis

    Continuous, very small reverse voltage on electrolytic capacitor

    I designed and built a circuit that works as desired, but I am concerned about a several nanovolt reverse voltage that is continuously developed across one electrolytic capacitor. The minus side of the cap is tied to the base of a NPN BJT. There is a 10K resistor also connected from the base...
  13. ccurtis

    PIC 8-bit mode TX and 9-bit mode RX on same USART?

    I am happy to report that on my 18F series device, I can successfully receive 8 bit and transmit 9bit on the same USART.
  14. ccurtis

    PIC 8-bit mode TX and 9-bit mode RX on same USART?

    Thanks, folk. I expect to try it and will let you know after I do. I like to check with youse experts first so maybe to save time in case someone has done it successfully already.
  15. ccurtis

    Force the state of PIC I/O pins for reprogrammer use

    Okay, thanks. I was hoping that the PICKIT3 could possibly set the port pins to high impedance, or as inputs, before trying to connect, via the MCLR pin, but I guess that's not certain.
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