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  1. crutschow

    Mosfets as voltage dividers.

    Rebuilding it why? Can't tell about adding variable voltage (power) and current control unless we see the schematic of the supply.
  2. crutschow

    Can I remove DC motor driver's speed control potentiometer and drive it with microcontroller DAC output ?

    You need a voltage to PWM board such as this, to drive a PWM to Motor driver, such as the D4184 posted by BJ.
  3. crutschow

    pls help need to pass for my finals

    So what are you going to have the servo do?
  4. crutschow

    pls help need to pass for my finals

    First decide what you want the servo to do, and then you can determine what the required rest of the circuit should be.
  5. crutschow

    MOSFET circuit for latch to enable switching 12 V battery power by micro-controller.

    I suggest switching the 12V, as that would eliminate any quiescent power taken by the converter supply with no output load. Below is the LTspice sim of a high-side P-MOSFET / BJT latching switch that should do what you want: It requires a positive going (0V to 3V) pulse to turn on, and a...
  6. crutschow

    MOSFET circuit for latch to enable switching 12 V battery power by micro-controller.

    So is that a momentary or steady digital signal? Can it be either a high or low signal as needed? Is it the same digital signal or two separate digital signals?
  7. crutschow

    Marconi 4461 dial cord nightmare

    Typically there is a small coil spring similar to the one below, that the cord connects to for maintaining the cord tension. The string length is such that the spring is slightly extended during normal operation. Without that, the cord is unlikely to work. Does your cord have one?
  8. crutschow

    Looking for a 12v 'micro ups' circuit to last 1-2s at 2A

    A super capacitor such as this 1.6F, 16V unit should work. Its voltage will drop about 2.5V when suppling 2A for 2 seconds, which should be sufficient to keep the camera activated.
  9. crutschow

    Using mosfet to switch 12V to a load with a hard ground.

    Yes, a BJT will work upside down, but with very low current gain.
  10. crutschow

    Want to make a box that will open at a programmed time.

    The latch could be one of these. The lid you will likely have to build or modify.
  11. crutschow

    VOIP setup for paging system to a warehouse horn

    If I understand correctly yes, you are missing something. The Cisco ATA 191 has a POTS current output of around 20mA into a 600-1200Ω load, so you must add an interface to convert that to the AC signal voltage for the Bogen. Also it puts out a 40-90V ring signal @ 20Hz into a open circuit...
  12. crutschow

    Using mosfet to switch 12V to a load with a hard ground.

    Yes. A P-MOSFET's normal operating voltage is positive, source-to-drain (negative drain-to-source). The diode is to suppress any negative spikes from the inductive horn load that might otherwise damage the MOSFET.
  13. crutschow

    Using mosfet to switch 12V to a load with a hard ground.

    Here's a high-side P-MOSFET switch to power the grounded horn: It powers the horn with a 3V to 12V input. The P-MOSFET can be any with at least a 15A, 30V rating.
  14. crutschow

    Revamping my Kenwood speakers

    You should be able to use that same crossover network for the new speakers. Are you replacing the speakers for some reason other than to just have ones with a greater wattage rating, as I see no reason to go with speakers that have a higher rating than 120W?
  15. crutschow

    16 ohm to 8 ohm quad box conversion

    So your choice is 4Ω or 16Ω. Which will your amp be happier with?
  16. crutschow

    How to reduce IR sensitivity for can trash

    Our kids had to get rid of their electronic trash can in the kitchen, because their dogs would cause it to open as they walked by, allowing them to feast on whatever was in the can.
  17. crutschow

    Question about DC current flow

    No. Solid wire and stranded wire of the same AWG have the same resistance, and carry DC current with the same voltage drop.
  18. crutschow

    LED Circuit for Electric Fence Light

    I recommend using real neon lamps or tubes in series with a high resistance for the indication. The current LEDs require to light will likely kill the fencer voltage.
  19. crutschow

    IRFP4332 250V Mosfet Rise & Fall Times

    Do you have a diode across the motor to carry the motor current when the MOSFET is off? Post a schematic of what you have.
  20. crutschow

    Solenoid alternative

    Not enough info-- How much force is needed to move the "component". How fast does it need to be moved?
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