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  1. (*steve*)

    I thought I'd measure the leakage current of a few caps

    After measuring the leakage in some diodes, I thought I'd measure the leakage in some caps. I have some nice (we'll find out how nice) 330pF polystyrene capacitors, and for comparison an X rated 3n3 capacitor. The 330pF capacitor measures 1.95x10-13A, that's 195fA with about 12.8V across it...
  2. (*steve*)

    High Voltage Probe and DMM internal impedence question

    I just measured the impedance of one of my multimeters (a Tektronix DMM916). It reads either 10MΩ or 9MΩ depending on the voltage range. On the 4V range it reads 11MΩ, on the 40, 400, and 1000V range it reads 10MΩ. These were read on my HP973A. On the mV range it is also 10MΩ Reading it...
  3. (*steve*)

    RF Circuit Battery Efficiency

    Sure, it's an H bridge. What is its quiescent current? Can you do better?
  4. (*steve*)

    Surface Mount Part Identification - TC

    Yeah, I was impressed when I saw the first 1μF SMD ceramic. Then I was impressed when I saw 10μF. After seeing 100μF, I had learned to expect the unexpected and vowed not to be impressed until I see 1000μF. I'm almost impressed again.
  5. (*steve*)

    I purchased a semi-automatic espresso maker that has a perplexing electrical issue.

    You don't have line and negative. You have line and neutral. In many countries neutral is earthed, but it is not safe to rely on it. Can you plug it in the other way around?
  6. (*steve*)

    Digital Signal Is Transmitted?

    Depends on the number of bits per baud. See trellis modulation for an example.
  7. (*steve*)

    Help with wiring a plug

    Yeah, it is the ground for that power supply (well, it's the negative rail -- I'm assuming it's ground, but it might not be)
  8. (*steve*)

    RF Circuit Battery Efficiency

    The radio module powered by the 3v3 regulator, does it need to be powered up all the time? You can probably reduce your power demands significantly by turning it off (possibly by using a 3v3 regulator with an enable input) when not required. The same is true for other support functions. Don't...
  9. (*steve*)

    I just thought I'd measure a few diodes V vs I

    And now the BE junction of a 2N3904 transistor: I really had to hold my tongue right to make some of those measurements! Now the leakage and noise were affecting my readings!
  10. (*steve*)

    I just thought I'd measure a few diodes V vs I

    With a little more care, I've managed to get some readings for a 1N4148: I had to allow some settling time for the readings below 10-9A, but there's no real sign (yet) of leakage (or bias currents) affecting my readings.
  11. (*steve*)

    Mains Vpp

    RMS values involve squaring, averaging, and taking the square root. Mathematically, doing that will always give you a positive number. This calculation gives you the DC voltage which would result in the same heating effect in a resistor. If you consider that reversed voltage results in heating...
  12. (*steve*)

    I just thought I'd measure a few diodes V vs I

    For this first (rough) try, the voltage was calculated rather than measured. The battery was a 12V lead acid battery chosen because, under the load used here (a 10k decavider) the voltage remained fairly constant over the period of the test (it dropped 5mV). There decavider has 0.005%...
  13. (*steve*)

    I just thought I'd measure a few diodes V vs I

    This information is very useful if one is protecting the input of an electrometer. Google "low level measurements handbook Tektronix" for more information. fA leakage is what you require. With my current setup, that's hard to measure, but it would be interesting to see how close I can get.
  14. (*steve*)

    Mains Vpp

    Measuring the mains with your oscilloscope is potentially dangerous. Please be careful
  15. (*steve*)

    I just thought I'd measure a few diodes V vs I

    Did you ever wonder what V vs I looks like for diodes for very low forward (and reverse) voltages? Well I decided to run some tests today, partially to see how low I could go before noise got in the way. At present I don't have a shielded enclosure etc, so all of this was done with banana...
  16. (*steve*)

    Woo-Woo Charging...food for thought

    I charge glasses with champagne. Although after I do it they're all wet and it's hard to read.
  17. (*steve*)

    Woo-Woo Charging...food for thought

    *BANG*
  18. (*steve*)

    Looking for a high current darlington transistor.

    When you choose a transistor, be very sure to carefully read the specs. Maximum voltage and current can't be achieved together, the maximum power dissipation can often not be maintained indefinitely without exotic heatsinking, and beware of secondary breakdown.
  19. (*steve*)

    building a HF transceiver

    In some countries.
  20. (*steve*)

    Multi meter question?

    This is an interesting article.
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