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  1. Sunnysky

    Test jig for testing production PCBs

    Next time do some research on Design for testability (DFT) at the board level or system level. This must be done at the same time as defined the Design Specs for Functions. But being an R&D and Test Enginerr for many decades, I know this afterthought occurs and when no headers or loop back...
  2. Sunnysky

    1980 Soviet Radio Cassette amplifier problem.

    What isn't clear to me (no pun intended) is the harmonic distortion from non-linearity at various stages when distortion occurs and confirm it is not from clipping or saturation ( by audio coupling high impedance to external headphone). Once the node where distortion occurs at a node then...
  3. Sunnysky

    1980 Soviet Radio Cassette amplifier problem.

    I've lost track what you are trying to accomplish because you cannot get more power when it is clipping with too much gain. You can only get more power with a lower impedance speaker. That's Why I said reduce gain or just dont go past clipping. try an external speaker.
  4. Sunnysky

    1980 Soviet Radio Cassette amplifier problem.

    OK Thankyou for the quick results. Good luck. I missed that. Without a scope, one needs a high impedance listening device to sample each stage to see where distortion occurs. From my simulation, your DC values seem near normal range, so I assume your pots are set to optimum.
  5. Sunnysky

    1980 Soviet Radio Cassette amplifier problem.

    1) Measure the AC voltage across C35 500uF when output is 900mVac, Any mV here is a loss in output power. This can be increased to x mF. Use battery V- as Gnd for AC measurements. ( more later)** 2) Also measure DC R of speaker. It should be ~ 1/2 of rated speaker impedance. e.g 4 ohms(DC) for...
  6. Sunnysky

    Design bass amplifier

    What do you suggest for others to use as a replacement? LM3886?
  7. Sunnysky

    Nichrome wire help

    0.4mm 26 AWG 8.992 Ohm/M 50cm = 4.5 Ohms I=V/R=12.5/4.5=2.78A P=VI=12.5*2.78A=35W
  8. Sunnysky

    Noise Activated Switch, with a Difference.

    Make a list of all problems in list form with test results and expected results and an accurate schematic.
  9. Sunnysky

    What specs are the most important when swapping transistors with another type?

    The devices you chose look like good replacements. I believe they include a small emitter resistor to share currents in multiple emitters inside and also give more consistent current sharing with parallel devices. Normally this is also shared externally by adding emitter R's for each device to...
  10. Sunnysky

    Microphone and camera using same power sounds like crap

    A Microphone load may be 1k~10k so to filter noise above 20Hz use ~100 in series to mic with 47uF to 100uF at output.
  11. Sunnysky

    Design bass amplifier

    affordable log frequency response analyzer ( = Audacity =free on any PC. ) I just imported some music (Bob James) and selected some portion and >Analyze> Plot frequency Spectrum... You can also generate a Sweep signal = "Chirp" and drive your audio to test it then use Aux input to check response.
  12. Sunnysky

    BJT transistor saturation

    Vce(sat) specs are usually Ic/Ib=10~20 and the Vce/Ic=ESR is a calculation to make useful projections of Vce vs Ic. But on the fringe , Saturation is the effective rapid decline in Hfe vs Vce for various Ic levels. In a linea amp operation into a low impedance load, Vce<2V for me is considered...
  13. Sunnysky

    Design bass amplifier

    If you have a decent 8 Ohms subwoofer (12") then you cnan drive it down to 10Hz with this. for reasonable power. The breakpoints for input and output are the intersections of impedance in Red shown on the impedance chart below.
  14. Sunnysky

    LED specification - All about 3mm & 5mm LED's

    3.3V Red's are pretty bad and colour of light without lens colour is vague.
  15. Sunnysky

    LED specification - All about 3mm & 5mm LED's

    The threshold voltage at 1mA is dependent on the wavelength . This is true for all clear case LEDs. Red/Yellow Vt~1.6 635nmD to 592nmD White/Blue/Green 415~525nmD 2.6V Any Vf measured at rated current again depends on Pd = ~1/ESR +/50% of the chip.
  16. Sunnysky

    1980 Soviet Radio Cassette amplifier problem.

    The fix is either attenuate input signal or reduce power amp gain as I indicated. The problems I stated were "Your input signal and hiss are too strong"
  17. Sunnysky

    Power source for smoke detector

    you know that's what I meant :rolleyes::)
  18. Sunnysky

    Glowing LED Bulb - How Does Circuit Flow

    There are 4 Vin vs Vout quadrants or trigger polarity conditions in Triac switches and the sensitivity is different depending on if you choose line or neutral switching. When Neutral switching leakage may be less but stray E field on line voltage on the wires to the bulb creates more electric...
  19. Sunnysky

    Dimmable led drivers?

    This LED driver is NOT meant to be dimmable without issues. It provides a CC output of 300mA +/-3% with TOO WIDE an input range for triac dimming to be practical. max/min =265Vac / 85Vac is 3.4x ratio so the output will track and stay constant over this RMS voltage ratio. So when you want to...
  20. Sunnysky

    Really basic circuit help needed (swtiches, LED, resistor and usb)

    It is so much easier to buy a 6 port USB hub to charge any mobile with the suitable lightnng or micro connector and let the mobile charge with 2.4A available on any port and forget about indicators. Use the mobile to indicate when it is full charged.
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