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  1. Sunnysky

    Digital Space Noise Detector

    No it is not truly random. Over sufficiently long periods, there are repeating cycles. 7 , 11 , ~10ky etc Even the Mayan Calendar shows these longer periods between major events that are linked to celestial magneto wobbles of rotational , orbital and inertial frequencies of planets. Have you...
  2. Sunnysky

    Amplifier SMPS died mid play

    This ought to be returned to supplied and request an RMA. It is beyond normal repair. The damage is extensive and clues from the Cap outgassing and mylar discoloration without a blown fuse, indicate an unstable condition resulting in excessive thermal losses. Assuming interconnections are...
  3. Sunnysky

    Simplest BJT configuration for a SPDT, single pole double throw switch

    define SPDT in measurable terms or delete this useless question.
  4. Sunnysky

    Switching DC motor with TIP122 and Arduino

    You have some good advice already. I would approach it like a Thevenin source and load impedance and find out what the values are or need to be for the supply, converter and load. In order to regulate torque with current and low loss the supply must be the lowest ESR, then the "switcher" must...
  5. Sunnysky

    Synchro motors for wind direction indicator

    - any sync motor including steppers needs datum or home sensor for 0 deg. - any wind vane needs a damper to prevent "gust inertial overshoot" to be critically or over-damped. It can be small but must be damped. _ I was on a team in my 1st job to design the world's 1st wind-powered arctic-ice...
  6. Sunnysky

    Hit Sensor

    I would do it this way. - 25 cent electret mic to pullup (R determines gain (330 to < 3k3) to Vbat (3.6 Lipo or Li Ion) - diode peak and slow decay RC. to CMOS inverter to R+ LED and/or piezo buzzer - This will flash LED once for the duration of RC time value e.g. 250+ ms but very bright using...
  7. Sunnysky

    Looking for suggested dynamic microphone power level

    Its a slang abbreviation for Your Mileage May Vary.
  8. Sunnysky

    How does capacitor C2 discharge ?

    I will attempt to explain from power-up as follows, but it is almost identical to the basic dual NPN astable vibrator circuit except there is only one flyback cap so there is only one sawtooth polarity. 1. The initial condition for C2 & C1 = 0V thus Vbe=starts near 0 with weak pullup from...
  9. Sunnysky

    DIY electromagnet

    work out the Ek , kinetic energy = effic.* electrical energy , magnetic force to reach max speed, displacement then repeat to stop.
  10. Sunnysky

    Looking for suggested dynamic microphone power level

    The advantage of the 25-cent mic is the open back cancels distance sounds so it amplifies near sounds only with the mic near the corner of the lips. This is great to eliminate feedback with a loudspeaker due to the far field attenuation. The bad news is quality if this feature is all over the...
  11. Sunnysky

    DIY electromagnet

    I think you will be very disappointed with a linear magnetic actuator for force, power and size to pull a robot arm with a wire. You would do far better with a small gear motor and large spool to take up the wire with loop to push-pull and spring tensioner pulley for the wire.
  12. Sunnysky

    How does capacitor C2 discharge ?

    TOT is self-biased with negative DC feedback using R11=100k between C-B and emitter R2 Bypassed for high AC gain. Since T2 has a grounded emitter it also has high gain and inverting thus C2 is "positive AC feedback with gain >>1) which automatically makes it an oscillator. This type of...
  13. Sunnysky

    Interesting Power Supply Issue

  14. Sunnysky

    Interesting Power Supply Issue

    I re-arranged your schematic. Feel free to edit and export shortcut link like this. https://tinyurl.com/28sbdegc
  15. Sunnysky

    Interesting Power Supply Issue

    It would be easier to analyze what output is needed and replace this mess with something better. It looks pretty low power. It seems the source was measured at 160V and R73 scales that down to 1% at R32. With the revised schematic comes revised hunches. Now it looks like a zero-crossing...
  16. Sunnysky

    Interesting Power Supply Issue

    Not sure on purpose of Q9 but Vbe is reverse biased to -8V and with DMM probe between Q9-b and GND will certainly trigger Q9-be to short circuit failure and start a cascade of reactions. This is a puzzle since Vebo = 6.0V so why use it at 8V reverse bias? and Q8 is also reverse biased except...
  17. Sunnysky

    Need help troubleshooting control board

    It seems the company is gone and the original website was bought out by a Chinese lottery. There might be some useful specs on the archive but I wouldn't expect it. More direct to resolve is to analyze the purpose and best solution. Your tire changer needs a motor and you have some sort of...
  18. Sunnysky

    Reducing brightness of LED bulb

    It will be difficult to find the current sensing resistor for this constant current source. However if you find a resistor with the constant voltage drop used for current sensing, by increasing the resistor value of that current sense you can reduce the current
  19. Sunnysky

    Need help to identify this zener diode

    The diode checker should read 0.6 and open in reverse zener being > 2V If the battery cells are aged and mismatched >10% voltages or < 3V you have more problems to consider.
  20. Sunnysky

    Need help troubleshooting control board

    https://www.lektronix.com/equipment/fiel-srl-1018a-01/274142 repair?
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