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Type: Posts; User: rompelstilchen

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  1. Closed: Re: humbucker preamp - j201 gain is 1:1, why ?

    I got these values, how can I calc gm and gain ?

    what is the difference between gm and gain ?

    155782

    - - - Updated - - -

    I got these values, how can I calc gm and gain ?
  2. Closed: humbucker preamp - j201 gain is 1:1, why ?

    Hello,

    I wanted to build a humbucker preamp, allowing me to learn JFET amplification in the context of electric guitars

    someone pointed once this circuit to me
    ...
  3. Replies
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    Closed: Re: gamepad black conductive compound

    tried yesterday with epoxy and graphite...meh
    I could maybe add some more graphite on top while it dries..but it will wash away

    I found a formula yesterday, but some parts would be hard to find
    ...
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    560

    Closed: gamepad black conductive compound

    Hello,

    I want to make my own game controler

    so I was wondering, as I would etch the pcb, what is the black stuff they cover button contacts with ?

    I mean I can order rubber buttons...
  5. Closed: Re: I cannot power that pelletier module

    no idea... just trying to follow this tutorial : https://www.instructables.com/id/Peltier-Cooled-Cloud-Chamber/

    I'll purchase a piped cooler like the one he uses, this gotta work
  6. Closed: Re: I cannot power that pelletier module

    I can try many different voltages
    yet, finding datasheets is not easy
  7. Closed: Re: I cannot power that pelletier module

    yes, checked the temp with an ir temp "gun"
    I am indeed building a bigger cooler/double fan apartus :-)
  8. Closed: I cannot power that pelletier module : TEC2-25408

    Hello,

    I have tried to power that pelletier module with an AT power supply but I reached max -10C or something

    so I ordered a 12V 10A power supply,

    as I measure the pelletier module, it...
  9. Closed: Re: LM3940 (3.3V reg) cannot supply 9V buck-boosk ?

    it does not work, I added a 33F like in the datasheet , yet it's not working
  10. Closed: Re: Audio IC (rec/play/spi) that does not s..

    wow, nobody ever needed a good audio ship ?

    #deception :-(
  11. Closed: Audio IC (rec/play/spi) that does not s..

    hello,

    I really feel like asking for the moon on google, but I have been digging for a long while, yet I am desperate to find an IC that rec/play audio with the least basic features :

    -...
  12. Closed: Re: LM3940 (3.3V reg) cannot supply 9V buck-boosk ?

    Ok thx, I'll check this out
  13. Closed: LM3940 (3.3V reg) cannot supply 9V buck-boosk ?

    Hello,

    I use a 3.7V 16850 cell that gets boosted to 9V (board : https://www.aliexpress.com/item/32844818160.html?spm=a2g0s.9042311.0.0.27424c4dSXahMo)

    as I sometime, have to recharge my cell, I...
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    Closed: Re: mosfet J201 -> DC motor switching

    thanks guys I am a complete dummy with analog electronics, first time I use a PNP
    also guessing I fried the poor thing

    I'll make the change and test these

    ;-)

    - - - Updated - - -

    ok, it...
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    Closed: Re: mosfet J201 -> DC motor switching

    I probably was on ***** yesterday, the schematic is not correct, I took the wrong datasheet

    here is the actual schema

    150615

    do I have to add a resistor or something ?

    [ ps : I changed...
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    795

    Closed: mosfet FDN340P-> DC motor switching

    Hi,

    I want to do PWM from an mcu using a FDN340P mosfet, driving a dc motor, so I made a test, without the mcu first

    if I set the gate to 0 (vss) the motor runs smoothly (200mA)

    if I want to...
  17. Closed: Re: digital aaudio - 4066 for audio switching ?

    google says "a humbucker will probably range from 400 to 800 mV or more." (just realised I did not mention it was to switch guitar pickups signal)

    datasheet "says" it has low charge injection...
  18. Closed: Re: digital aaudio - 4066 for audio switching ?

    found this for the preamp

    http://www.till.com/articles/GuitarPreamp/images/preamp.gif

    - - - Updated - - -

    TS3A44159 is 3V and lo ON res, I'll try it
  19. Closed: Re: digital aaudio - 4066 for audio switching ?

    so you mean switching after the preamp ? what sort of preamp ?

    I hesitate between these two

    http://www.autex.spb.su/ad/SSM2404.pdf
    http://www.ti.com/lit/ds/symlink/ts3a44159.pdf
  20. Closed: digital audio - 4066 for audio switching ?

    hello,

    I wanna switch audio signals (guitar pickups) with a 4066 instead of using 4PDT mechanical switches

    considering I would add some dc to the signal to be around 2.5v, yet is it a good...
  21. Closed: Re: calculating saturated NPN drives me nuts

    "Maybe you should try Rc=47ohm and Rb=100ohm. "

    dude it works
    so I have to have Ic=100mA ??? I cant choose a smaller current ?
    jeee...I'll try with a 2222

    - - - Updated - - -

    found this...
  22. Closed: Re: calculating saturated NPN drives me nuts

    double checked everything
    I tried a 50k pot for Rb, it should switch
    I tried with another 818 that has a different id on its back, even worst, no matter what, the output is always 5v
    I'll go to...
  23. Closed: Re: calculating saturated NPN drives me nuts

    I tried 20k , does not work either...I dont get it , I tried 1K, 230k, 500k, now 20k, I should get closer somehow...that bloody p of s does not switch at all
    from 5v, it barely goes to 4.5v

    tried...
  24. Closed: calculating saturated NPN drives me nuts

    Hello

    I try to invert a 5V ttl with a bc818...I need to figure Rb when Rc is 1K (guess I dont need high current since there is no load)

    in the datasheet, the BC818 has a gain between 250 and...
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    Closed: Re: comparators - pull up or not ?

    if USB (through mosfet) and VIN (through VREG) both produce 5V and reach the same 5V point in the schematic

    then a simple diode would do the trick, right ?
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