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  1. bertus

    Why a pull down resistor for transistor base

    Hello, To have a transistor in saturation for switching, it is a common use that the base current is about 1/10 of the collector current. Some times for small transistors a base current of 1/20 of the collector current is used. That is why you will see a 1K resistor in stead of the calculated...
  2. bertus

    how much voltage can a vacuum capacitor suck up

    Hello, Vacuum capacitors are most times used where very high voltages occour. http://www.iequalscdvdt.com/vacuum_capacitors.html Bertus
  3. bertus

    Why a pull down resistor for transistor base

    Hello, Are you sure about the current through the led? Small leds will have a maximum current of about 20 mA, most times 5 to 10 mA is enough to make it good visible. Bertus
  4. bertus

    Why a pull down resistor for transistor base

    Hello, I have made a comment in your drawing: Bertus
  5. bertus

    Comedy Thread

    Robot act chair:
  6. bertus

    Eric basic electronics modules on the internet archive

    Hello, Here I found a couple of modules from the ERIC series. ERIC ED099498: Module One: Electrical Current; https://archive.org/details/ERIC_ED099498 ERIC ED099499: Module Two: Voltage; https://archive.org/details/ERIC_ED099499 ERIC ED099500: Module Three: Resistance...
  7. bertus

    Eric basic electronics modules on the internet archive

    bertus submitted a new resource: Eric basic electronics modules on the internet archive - Eric modules on the internet archive Read more about this resource...
  8. bertus

    Novel voltage doubler circuit need help plz

    Hello, Perhaps you should read the following pages: https://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/voltage-multipliers/ https://en.wikipedia.org/wiki/Voltage_multiplier Bertus
  9. bertus

    Heathkit Super Clock GC-1195 w/chimes

    Hello, Yes, R219 should be changed if you are planning to use a led for the illumination of the dots. When you leave the value the same, the led will be on premanently. Bertus
  10. bertus

    New project

    Hello, Perhaps you can find some info in the links of the following pages: http://educypedia.karadimov.info/education/diypedalpower.htm http://educypedia.karadimov.info/education/physicsexperimentsmotor.htm You might experience that not all motors can be used as a generator. Bertus
  11. bertus

    Why is it PNP instead of PPN for transistors

    Hello, Perhaps you should take a dive in this book: https://the-eye.eu/public/Books/Electronic%20Archive/Transistor_From_Crystal_to_Integrated_Circuits_World_Scientific_1998.pdf Bertus
  12. bertus

    Heathkit Super Clock GC-1195 w/chimes

    Hello, When you look at the schematic for the dot, there is a resistor over the C-E of the transistor: For the led, this resistor should have a much higher value. When you use a 100 Ohms for the led itself, the resistors on the transistor should be in the range of 220 to 1000 Ohms. See what...
  13. bertus

    Heathkit Super Clock GC-1195 w/chimes

    Hello, You might want to have a look at the manual: https://www.vintage-radio.info/download.php?id=84 I have composed a schematic from that manual: Bertus
  14. bertus

    Noisemaker Revenge Machine

    Hello, When you want to have space to allow the motor the turn around and no need to have the motor go forward and backwards. Bertus
  15. bertus

    datasheet and information about 6c17504 and 1d17409 8pin ic

    Hello, It can well be that the chips are OEM products. The numbers will be inhouse coded and can not be found on the internet. Bertus
  16. bertus

    Circuit help: momentary bi-directional DC motor control

    Hello, In the old days we had an automatic car antenna: https://www.google.com/search?as_st=y&tbm=isch&as_q=automatic+car+antenna&as_epq=&as_oq=&as_eq=&imgsz=&imgar=&imgc=&imgcolor=&imgtype=&cr=&as_sitesearch=&safe=images&as_filetype=&tbs= Those where put out when the radio was turned on and...
  17. bertus

    a mosfet driver question

    Hello, Just compare the datasheets. They seem to be pin compatable. The MC is a little bit faster. Bertus
  18. bertus

    Stage Line 500W amp repair project

    Hello, As for the scope, have a look at the attached document. Bertus
  19. bertus

    Noisemaker Revenge Machine

    Hello, I have seen SMPS adapters creating a dead short, blowing fuses. Bertus
  20. bertus

    Noisemaker Revenge Machine

    Hello, If you switch the DC adapter very fast, it depends on the type of DC adapter. When it is a SMPS adapter, it might fail soon, as that is not upto fast switching. When it is an old type of adapter, the output voltage may drop a bit when switched off and come back when switched on again...
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