Type: Posts; User: schmitt trigger

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  1. Closed: Re: Electronic Load Circuit for 380 Vdc (2A to 3A) Power Supply

    The only reason electronic loads are better vs power resistors, is that it is continuously adjustable (or in very tiny increments) and its transfer function can be changed from resistive to constant...
  2. Replies

    Closed: Re: Halogen Lamp Limit Resistor?

    What Brad says is correct!

    I once made the mistake of running a halogen lamp thru a dimmer, and shortly afterward the bulb started to darken.
    Don’t know the exact failure mechanism, but believe...
  3. Closed: Re: How to measure differential signals using an Oscilloscope has to make sure that both probes are properly and equally compensated.

    A good way I have found is to compensate each probe individually (with the scope's CAL SIGNAL output).
  4. Replies

    Closed: Re: Bridge Rectifier won't Rectify

    I remember seeing the schematic for a Tektronix HV probe similar to the one in the photo. The compensation network was really complex, as you can tell from the several visible adjustments.

  5. Closed: Re: Optimally Accurate 28-bit A/D conversion

    Flash A/Ds anyone?

    Although I don't think 28 bit flash A/Ds were commercially produced. The power consumption alone would be humongous.
  6. Replies

    [SOLVED]Closed: Re: dc current gain variations

    Be aware though, that the specified Hfe is in the linear region. Which in this instance, it means a Vce of at least 5 volts.

    As the transistor approaches saturation, the Hfe will start to drop.
  7. Closed: Re: How stop Micro burning when GND & VCC short circuit?

    Very likely a recovery overshoot. Do you have access to a digital scope?

    -Either a SCR crowbar as discussed previously, which would latch and you'll have to remove the main supply to...
  8. Replies

    Closed: Re: Motor winding Temeparture

    Operating at higher voltages increase the core losses as well.
  9. Closed: Re: Tube filaments on 230v? What do I need to know?

    There is something additional, that was explained to me *decades ago* by a tube engineer: the maximum filament to cathode breakdown voltage.

    For instance the 12AX7 / ECC83 tube has only 180 volts...
  10. Replies

    Closed: Re: TLV4172 low-cost substitute

    Opamps have literally dozens of parameters, as others have mentioned. Only you know the circuit and application, and be able to determine what parameters are important, what parameters may be...
  11. Replies

    Closed: Re: overvoltage protection

    If you really want to do things right, select a crowbar IC which provides a hard SCR-gate drive, and which has both an accurate voltage threshold and an adjustable time delay to prevent nuisance...
  12. Closed: Re: 5 Transistors Linear Triangle Wave Generator

    I love discrete semiconductor circuits. Especially when they are simple and elegant like yours.

    But as FvM mentioned, Q4 and Q5 are gated current sources. Otherwise the capacitor would not charge...
  13. Replies

    Closed: Re: Low drop voltage regulator

    You should have included the datasheets in your message such that people here could perform a quick analysis and comparison of parameters.

    The only other parameter I would consider what is the...
  14. Closed: Re: I cannot power that pelletier module

    After all is done and said, this is a thermodynamic problem.
    -What is the fan’s airflow and under what static pressure?
    -What is the heatsink’s thermal resistance, with the calculated airflow?...
  15. Re: Help unlock microcontroler atmega644pa-mu

    You are finding exactly the reason to lock up a microcontroller: to prevent unauthorized copying or altering the code.
  16. Closed: Re: Make a led shut down immediately after power off

    You are absolutely correct Brian, but you still were able to get the gist of it.
  17. Closed: Re: Make a led shut down immediately after power off

    and put a series blocking diode between the rectifier and the bulk capacitor. Wire your LED right after the bridge rectifier, but BEFORE the bulk capacitor.
  18. Replies

    Closed: Re: Differential probe build

    Additionally, you must add a trim capacitor to frequency compensate your dividers, otherwise the stray capacitance will form a low-pass filter.
  19. Closed: Re: Help in using digital potentiometer with LM386

    I believe Klaus has figured your problem. You are connecting the POA pin to some sort of voltage.

    Speaking of supply voltages....Digipot's supplies are constrained to logic supplies. If you are...
  20. Closed: Re: High voltage (60kv) insulator material and glue

    Teflon is an excellent insulator. It is also easily machined.

    But most adhesives will not adhere to it either.
  21. Closed: Re: Small Inductor in Buck DC/DC Converter

    Very likely it is to suppress very high frequency noise.
    The larger inductor may have a significantly low SRF which makes it unsuitable to filter that HF noise. Thus a smaller inductor with a much...
  22. Replies

    Closed: Re: LM2575 variable 7A power supply

    The LM2575 is a switchmode regulator.... How can you predict that your simplistic transistor drive will dynamically share the current correctly, even if statically it "appears" to do so?
  23. [SOLVED]Closed: Re: OCXO Freq Stability Vs. Layout design guidelines

    What has worked for me, is to not place ANY copper traces or planes below the OXCO's footprint. They form an unintended heat sink.

    If you are using a ground or Vcc plane, place a keep-out area...
  24. Replies

    Closed: Re: 9V rechargeable battery circuit

    In addition to a wide initial tolerance, common zeners have a significant tempco and a very soft knee.
    In other words, *very sloppy* charging characteristics.

    As Klaus mentions, Li ion batteries...
  25. Replies

    Closed: Re: 12V to 220V with no isolation

    For low current outputs, this is quite common.

    There are many "Nixie" power supplies which increase a low voltage source (usually 12 volts), to the Nixie's anode voltage, which is anywhere from...
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