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  1. Closed: Metal detector with Arduino ADC channel.

    156825

    i need help with sensitive metal detector design. i'm using swg20 x 15 wound on an

    iron ring with 6 inch diameter. can this design be used for a sensitive metal detector by using
    ...
  2. Closed: Sensitive metal detector using microcontroller ADC channel.

    need help with metal detector circuit if i use arduino/PIC micro controller ADC channel.

    156811
    if i want to switch the coil inductor at high current using mosfet for greater depth. because...
  3. [SOLVED]Closed: Re: uc384x PWM DC-DC converter not regulating.

    156644

    i made my own voltage divider calculator for getting fixed voltage by using excel worksheet.

    and set the 100k trimmer by shorting its variable and one fixed pin to get 86k in series
    ...
  4. [SOLVED]Closed: Re: uc384x PWM DC-DC converter not regulating.

    156635

    the components listed within post#3 works fine with my design. the circuit now works as regulated boost converter

    with output voltage greater than the input. i put the divider resistor...
  5. [SOLVED]Closed: Re: uc384x PWM DC-DC converter not regulating.

    the input to the circuit is Vin = 9-25vdc. the output is 48vdc. i need to know the reason why the oscillator

    stops when i connect the voltage divider trimmer to Vfb pin of uc3843. voltage...
  6. Replies
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    1,507

    Closed: Re: current-mode boost converter UC3845

    with Vout = 48vdc. if the trimmer is set to the bottom then the voltage at Vfb = 3.1 volt.

    for Vfb = 2.5v by setting the trimmer at the bottom mean 10k + 4.7k = 14.7k in series with 0.8k.

    but i...
  7. [SOLVED]Closed: Re: uc384x PWM DC-DC converter not regulating.

    i will try it with 10R/10watt resistors in series but i don't have any specific rated load of 48vdc.

    how to decrease the output voltage to 14vdc. the output regulator trimmer not working to...
  8. [SOLVED]Closed: Re: uc384x PWM DC-DC converter not regulating.

    i want fixed Vout = 14vdc from Vin = 9v-25vdc not 48vdc. possibly it may be the problem

    of pin#2 Vfb = 2.5v which in this circuit is not 2.5vdc. i want 14vdc output but it give 48vdc how to reduce...
  9. [SOLVED]Closed: uc384x PWM DC-DC converter not regulating.

    156589
    156590

    the input to the circuit is Vin = 9vdc. output of the converter is 48vdc but the regulator trimmer is not working.

    connecting the trimmer with the Vfeb pin#2 of the oscillator...
  10. Replies
    28
    Views
    1,507

    Closed: Re: current-mode boost converter UC3845

    156566

    i made this circuit with all the components used instead of the current sense resistor

    at the source pin of the the mosfet. wound the inductor choke myself. the circuit input is 9vdc
    ...
  11. [SOLVED]Closed: Re: Flyback SMPS power MOSFET getting hot? uc3843 pwm converter

    for the time being the problem of power FET heating solved by adding a turn off RC snubber across FET.

    the power FET now heat up normally with load.
  12. [SOLVED]Closed: Re: Flyback SMPS power MOSFET getting hot? uc3843 pwm converter

    155626

    this protective turn off RC snubber? is it necessary with power FET?

    the xformer have RCD snubber with R = 47k/2w, C = 103pf/1kv & fast recovery diode FR107.

    - - - Updated - - -
    ...
  13. [SOLVED]Closed: Re: Flyback SMPS power MOSFET getting hot? uc3843 pwm converter

    155621

    the power mosfet don't have any RC snubber circuit. is it necessary in a flyback smps with power mosfet?

    the xformer have an RCD snubber with R = 47K/2W, C = 103pf & fast recovery diode...
  14. [SOLVED]Closed: Re: Flyback SMPS power MOSFET getting hot? uc3843 pwm converter

    155619

    i have PQ3230 core with fixed air gap of about 0.979mm. for this air gap Bmax = 0.2600T which is much higher.

    i have no tool to change the air gap. the frequency fs = 77 KHz, core area...
  15. [SOLVED]Closed: Re: Half bridge SMPS xformer turns calculation

    i wrote mistakenly 1500mT. it's 0.1500T or 1500 gauss.
  16. [SOLVED]Closed: Re: Flyback SMPS power MOSFET getting hot? uc3843 pwm converter

    155456

    this air gap of transformer as shown in the image ?
  17. [SOLVED]Closed: Re: Flyback SMPS power MOSFET getting hot? uc3843 pwm converter

    the figure above show an xformer have air gap & numbers of turns mentioned above.
    and the same problem occurs from the beginning that mosfet heating up. i want to stop heating of the power
    mosfet....
  18. [SOLVED]Closed: Re: Flyback SMPS power MOSFET getting hot? uc3843 pwm converter

    yes i measured it with DVM, but unfortunately i have no scope. i didn't understand why Vgs = 0.7v when Vcc = 21vdc.

    the gate series resistor at the uc3843 pulse is 22R/1w. and the Bmax for the...
  19. [SOLVED]Closed: Re: Flyback SMPS power MOSFET getting hot? uc3843 pwm converter

    i measured the pulse voltage of uc3843 in mu circuit today. it is 0.7v not 2v.
    Vcc of the uc3843 at the 47uf capacitor is 21vdc but pulse voltage = 0.7v

    primary clamp/snubber include 47K-2W...
  20. [SOLVED]Closed: Re: Flyback SMPS power MOSFET getting hot? uc3843 pwm converter

    without loading why mosfet heat up??? and when loaded mosfet get hot extremely. i 'm using 20NM60 power mosfet

    with this flyback battery charger circuit. it is a readymade chines switch mode...
  21. [SOLVED]Closed: Re: Flyback SMPS power MOSFET getting hot? uc3843 pwm converter

    i change the frequency of uc3843 oscillator by putting 10K variable resistor on the Rt/Ct pin.

    still it does not work and the power mosfet still getting hot without load. i think this is not the...
  22. [SOLVED]Closed: Re: Flyback SMPS power MOSFET getting hot? uc3843 pwm converter

    this power mosfet getting extremely hot even without any load connected.

    the box of the power supply act as heat sink not shown here.

    but mostly battery charger or power supply is not getting...
  23. [SOLVED]Closed: Flyback SMPS power MOSFET getting hot? uc3843 pwm converter

    155356

    today i built this flyback smps transformer for this circuit as shown above using PQ3230 core

    with Nprim = 24T (swg 26 x 4) , Nsec = 4T(swg 23 x 4) & Naux = 5T(swg 26 x 1). but the smps...
  24. [SOLVED]Closed: SMPS transformer for Half bridge topology

    155291

    i enter the operating conditions according to my specification

    fs = 50000Hz

    Bmax = 1786mT.

    & powerEsim calculate N0 = 10T (AWG24 x 6)
  25. [SOLVED]Closed: Re: Half bridge SMPS xformer turns calculation

    http://tahmidmc.blogspot.com/2013/02/ferrite-transformer-turns-calculation_22.html

    for transformer i 'm referring above URL. is the calculation based on this is correct?

    they consider half of...
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