Recent content by Wollowstone

  1. W

    How to make transistor ON

    Additionnal note: You can use simulator for those circuits, if you don't want to blow off your components. Under TINA and CircuitLab, you can use the NPN as defined by default; under LTspice, you have to specify the parameter Br ( beta reverse) since by default, it is set to 1.00 and not often...
  2. W

    How to make transistor ON

    Sure. Assuming the Vbe > Vbe_on, you will be in deep saturation, with almost or no "amplification" at all (the "beta" value won't be what you expect, though, probably close to 1, since beta is relatively more or less constant at low frequency, but only in active mode, not as you pass into...
  3. W

    Experiment to show that current leads voltage by 90° in capacitor (Using RC circuit & Oscilloscope)

    You can try the (excellent, imvho) video from Texas Instruments on their site: https://training.ti.com/ti-precision-labs-op-amps-bandwidth-bode-plots-cutoff-frequency?context=1139747-1139745-14685-1138800-13124 It is clear that on the time domain (generally what is available on a 2 channels...
  4. W

    Toggle between 2 LEDs on separate circuits in the same circuit?

    You have to supply a resistor for each individual LED, otherwise, only the one with the lowest threshold voltage will light up. Here, an example of what to do, with the two leftmost LED, and what to not do, the two rightmost LED. The circuit is made with TINA (TM), free simulator by Texas...
  5. W

    How can a MOSFET in TO220 handle this much current?

    The Vdss of 40V is the minimum garanteed voltage that can passthrough the IRF1404. The 121A is for a short pulse, as stated in the annotation (4) of the section Electrical Characteristics. Use the SOA (figure 8) to have an information which COMBINES voltage passing through AND current passing...
  6. W

    How to lower voltage of frequency signal

    A static voltage divider is nice, but the involved resistances have to be small, so that the "equivalent resistance" of whatever you add in parallel to one of the resistor appears "big" (1000 times, or higher), but that may draw a lot of current, if not too much, from the original source...
  7. W

    What to do with all these chips?

    Yes, he often spots "a mistake" in the circuit (or a limitation, whatever...) and THEN add a correction. You learn not just to "weld" components on a printed circuit, but "how to debug" a circuit. Not often the standard way of doing things which are more like: "and here, a circuit which work"...
  8. W

    What to do with all these chips?

    Some projects shown by Ben Eater, on You Tube, seems to use those chips. There are mostly related to building a computer on breadboards, and video card, etc.
  9. W

    Can integer variable store char value?

    Since, in theory, a character code can be ANSI 7 bits, EBDIC, HTML, ... for PORTABILITY, it is strongly suggested to use a char when a char is supposed to be used, and an int for an int. But sure, a sequence of 64 bits ... is readable in many possible ways, among other, when using an Assembler...
  10. W

    8051 UART Chart

    If you have access to it, I will suggest a look at section 18.3, "Interrupt-driven UART" of "Introduction to Robotics Embedded Systems" by J. W. Valvano, ISBN 9781074544300. ---------------- Updated: You can also see a summary using TI Acronyms for their MSP432 at...
  11. W

    Interesting circuit usb with 2 led lights with different brightness

    Could be based on a shift register used as a circular buffer with the "click" playing the role of a clock edge signal. Part of the problem could be to initialize the original state of 0s and one 1.
  12. W

    Multimeter testing led

    Even if it is an auto-range, you may have to "select" the measure that you wish. As example, on ANENG(TM) AN8008, the same dial position can be used for Ohm-meter, Capacitor, Continuity and for Diode, and by default, it occurs to be on the Ohm-meter. You have, in this case, with the gold button...
  13. W

    Logic mosfet pwm

    True, but the current for the regulator, its comes from the Arduino which is limited to 200 mA from its 5V pin ( and 40 mA if it comes from a GPIO pin). (Unless it is a special board.) https://playground.arduino.cc/Main/ArduinoPinCurrentLimitations Should try without any other component, just...
  14. W

    Logic mosfet pwm

    The link that you supplied for the LED specifies that it need 300 mA, which is too much for the Arduino (for each GPIO, the maximum is 40 mA, for a total of all GPIO not exceeding 200 mA, unless you have a special board...). Try using an independent power source as source for the regulator. If...
  15. W

    What is KCL, KVL?

    KCL and KVL refer to the Kirchoff laws. Kirchoff Current Law (in a steady state, the sum of currents which enter in a node equal to the sum of the currents which leaves) and Kirchoff Voltage Law (the sum of the voltages, in any close loop, is zero).
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