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  1. Sunnysky

    ribbon code

    alec's part seems to be the closest match To reduce self heating, I would use 500 uH rated for 240mA with DCR of 7Ω which is two of Alec's chokes in parallel . These are like 1/4W resistors which would burn out with 1/2W. A lower DCR of 3Ω would work but increase dissipation power in 1000uF...
  2. Sunnysky

    ribbon code

    next question is why did it fail? why was it suspect? THis choke reduces the current surge charging up the 1000 uF cap to some voltage when switched on. The cap ESR may be lower than the choke DCR of 12 Ohms. thus the current di/dt =V/L where dt is the charge up time. This is a basic Current...
  3. Sunnysky

    Trunk Charger

    Does this charge from vehicle only when engine is running? 14.2V > current shunt ( 100mV @2A = 50 mΩ)> amplifier > current sense out. LiPo 4.2x3 =12.6 in Charge mode limited to 2A thus 14.2-0.1-12.6=1.5V drop Using a power Schottky diode , Vf options 0.4-1V @ 2A to block reverse charge. ALso...
  4. Sunnysky

    ribbon code

    The value is correct, but other options are DC current , Frequency - SRF and of course DCR. If this is critical, we need to know circuit parameters & application The red coating was added?
  5. Sunnysky

    Toshiba CRT TV fault... what could the problem be?

    I agree it is a HV problem. The flyback transformer operates at high audio f is making the noise and is connected to high voltage rectifer caps called voltage doublers which if touched will give a big shock , even after a long time.. Since the sound continues, it is working but with an arc...
  6. Sunnysky

    ribbon code

    is that Brown black red gold? 102 5% 1000 uH http://www.digikey.com/product-search/en/inductors-coils-chokes/fixed-inductors/196627?k=&pkeyword=&pv19=338&pv3=2&pv16=1&FV=fff40003,fff80013&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25 choose one with low DCR
  7. Sunnysky

    Amp In Protection Mode

    I agree @de Edd, except I've been saying all along , a positive DC output to speakers will only be caused by leakage R in Q603 in spite of working diode junctions.
  8. Sunnysky

    Common collector configuraton

    @Athul When using emitter followers ( preferred name over CC ) we think of them as Voltage Followers with a diode drop, as long as there is sufficient current in the base to "saturate" the base emitter using the minimum current gain.at specified Vce. This results in an output impedance at the...
  9. Sunnysky

    Common collector configuraton

    I meant to say if temperature drifts higher using a true voltage source, you must allow for the Shockley (NTC) effect in the transconductance model , when it is far simpler to use the Norton equivalent circuit with an external base R and assume a range of current gains provided in the datasheet...
  10. Sunnysky

    12VDC to 3.3VDC LED Metered after resistor

    Thanks Steve for affirming my past experience. 10 yrs ago my LED client in NZ was having 10% Field,returns with at least 1 in 20 per unit bad LEDs and one symptom was increased capacitance causing a loop on VI sweep on bad LEDs and some still working also had similar peculiarity. I decided to...
  11. Sunnysky

    12VDC to 3.3VDC LED Metered after resistor

    try using base emitter as a Zener. The current is very limited before failure unlike collector emitter breakdown
  12. Sunnysky

    Need help finding a weight sensing on/off switch? Like in lawn mowers.

    If the seat has no springs, this can be a mechanical challenge. An optical reflector thru hole in the seat might work powered by ignition switch.
  13. Sunnysky

    Common collector configuraton

    I was referring to the common practise of choosing a min hFE when Vce is saturated or less than 2V at high current rather than using the transconductance model for reliable operation.
  14. Sunnysky

    Amp In Protection Mode

    Yes I believe Q603 is at fault, but not from appearance
  15. Sunnysky

    Obscure high power electronic device,what is it?

    Yes late 80's , the PSU and unit will have date codes with their S/N's Made in California during the Silicon Valley era.
  16. Sunnysky

    Common collector configuraton

    Since Vbe drifts downward with rising temperature, it is more useful to view transistors as current amplifiers within several decades of specified output current. However in emitter followers The output will be just the Below Vbe and load current is limited by emitter resistance, but as long...
  17. Sunnysky

    12VDC to 3.3VDC LED Metered after resistor

    I guess Not all LEDs have the same failure threshold , but most will fail or be damaged with lower efficacy.
  18. Sunnysky

    That awful "yellow glue" - How to remove it?

    I would trust the MG . If sealed , it should last years.
  19. Sunnysky

    For LEDs, is there a device that maintains a steady "power" output, interms of watts or amps?

    You can model this UV Diode as Vf=2.8 +If*18Ω THen ensure your Vreg is stable to adjust Series R This is my method which has worked for decades from sources with tight tolerance. Your mileage may vary.... Thus is using 12.0V Reg and choose MOSFET switch with 0.2V drop (11.9...
  20. Sunnysky

    12VDC to 3.3VDC LED Metered after resistor

    LEDs are rated at -5V ( reverse bias ) at 10uA If you apply -12V in reverse, you will damage the LED. Replace it and dont do that again.
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