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  1. crutschow

    Replacing electrolytic cap with non-polarized a mistake with tube radio?

    A black band around a non-polarized cap can indicate which wire is connected to the outside foil on a film capacitor. This can be important to know when using the cap in high frequency circuits. For example, if the capacitor were being used as a high frequency bypass to ground, you would...
  2. crutschow

    Replacing electrolytic cap with non-polarized a mistake with tube radio?

    If the non-polarized cap had the same capacitance and voltage rating as the original, then that should cause no problems, such as blowing the tube filament.
  3. crutschow

    Why use diodes in this circuit

    There are few motors that aren't. ;)
  4. crutschow

    On/Off switch MOSFET based

    Why is R3 scribbled in?
  5. crutschow

    Why Do DC Inverters Damage Items?

    A surge protector won't improve the waveform from the inverter. It might be cheaper to see if you can find a heating pad without any electronics (if they still make them).
  6. crutschow

    Why Do DC Inverters Damage Items?

    Does the heating pad have any electronics or is it a simple ON/OFF type. The electronic type could be damaged if the inverter generates a quasi-sinewave and not a true sinewave.
  7. crutschow

    Why use diodes in this circuit

    The diode is to suppress the negative inductive spike from the motor when the switch is opened, to prevent damage to the transistor or switch. Incidentally the transistor circuit won't work as shown with the posted control voltages. The OFF voltage must be equal to the supply voltage (12V here)...
  8. crutschow

    Solid-State Switch?

    You can't use an N-MOSFET for a positive high-side switch in your application. :confused:
  9. crutschow

    Modify a motorized projector screen to run on batteries

    You will have to determine what the internal DC voltage is and how much current it takes. Otherwise you could measure the AC power consumption and buy a DC-AC inverter to run it from the battery. The problem with that is, you would need to shut off the inverter when not powering the screen to...
  10. crutschow

    Beta and VHS repairs

    I would buy an assortment of video recorder belts, since a bad or broken belt is a common failure in VCRs. Several assortments are available on Amazon.
  11. crutschow

    NE555 reset pin using transistor

    Without a complete schematic of what you have, I can not further help you.
  12. crutschow

    NE555 reset pin using transistor

    Below is the LTspice simulation of a 555 astable circuit with the output On (green trace) when the Enable input (yellow trace) is 5V and Off when the Enable input is 0.6V. Note that the first 555 pulse is longer than the rest (typical when the 555 starts oscillating), and the last pulse can be...
  13. crutschow

    How to make composite video black and white?

    That, of course, only applies to standard-definition interlaced video, not the 1080p the TS mentioned in post #10.
  14. crutschow

    How to make composite video black and white?

    Yes, it should have more than sufficient bandwidth for that, assuming the circuit is laid out with a good ground layout (preferably a ground plane) on a small board (no plug-in type breadboard).
  15. crutschow

    NE555 reset pin using transistor

    So you want the 555 to stop when the signal is low?
  16. crutschow

    NE555 reset pin using transistor

    Pin 4 has to be pulled below 0.5V for reset, which an NPN BJT or an N-Channel MOSFET can do. What "tranzistor" did you try? .
  17. crutschow

    How to make composite video black and white?

    I know of no ready built circuit but you could sum the 3 color signals of the VGA to make one black and white signal, and then connect that signal to the three VGA color inputs on you monitor. That should give a black and white picture. That could possibly be done with just a simple emitter...
  18. crutschow

    How to make composite video black and white?

    Turn down the color (intensity) pot on the receiver. Why do you want to eliminate the color? To eliminate it in the composite signal, you would have to sharply filter out anything above about 3MHz. Why would you want it converted to component video?
  19. crutschow

    LM380 in positive ground circuit???

    Below is a typical circuit LM380 circuit diagram. For your application just connect the Vs connection to ground, and the ground connections to -16V except the bypass capacitors and speaker ground. Reverse the polarity of the 500µF output capacitor (+ towards speaker) Also add a 0.1µF ceramic...
  20. crutschow

    555 Trigger

    The sensor should give a pulse out when it detects a noise. Does it? What voltage are you using to power the sensor and the 555? Note that the 555 takes a negative going signal to trigger it.
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