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  1. 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.
  2. 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)...
  3. crutschow

    Solid-State Switch?

    You can't use an N-MOSFET for a positive high-side switch in your application. :confused:
  4. 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...
  5. 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.
  6. crutschow

    NE555 reset pin using transistor

    Without a complete schematic of what you have, I can not further help you.
  7. 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...
  8. 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.
  9. 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).
  10. crutschow

    NE555 reset pin using transistor

    So you want the 555 to stop when the signal is low?
  11. 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? .
  12. 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...
  13. 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?
  14. 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...
  15. 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.
  16. crutschow

    Change 3 phase Steam Boiler to 3 phase Hot Water Boiler?

    A single-phase thermostat controlling a high-current 3-pole contactor (relay) may be cheaper.
  17. crutschow

    output of power supply reads 24V should be 12V

    To add to the info on the sense lines, they are the feedback connections that determines the output voltage, so they must be connected to the output terminals to get the correct output voltage. If they are not properly connected than the output will go to the maximum voltage the supply can output.
  18. crutschow

    Wire Size for Security Camera

    The cameras should have a power rating in their specifications, but the power draw is likely quite small (a few watts). 18Ga wire should be sufficient, even for the 80 foot run.
  19. crutschow

    Temperature Probe Testing

    Hard to say. I see no mention of how long it can provide power. I suggest a wide mount vacuum, bottle such as this, to store the water. It should have a minimum heat loss to ambient. You can heat it to temperature from the mains, and then use a battery powered heater to maintain the temperature.
  20. crutschow

    Soldering temperature indicator

    What laser? The IR temp gun uses a passive IR detector to determine the temperature from the radiated IR energy.
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