What does 1N4148 do

Discussion in 'General Discussion' started by April155, Jul 11, 2018.

  1. April155

    April155 Member

    Good day,all

    As we know: the main characteristic of the diode is the unidirectional conductivity, that is, under the action of the forward voltage, the conduction resistance is very small, and the resistance is great or infinity under the action of the reverse voltage. Because of the characteristics of the diode, the cordless telephone often uses it in rectifying, isolating, stabilizing, polarity protection, coding control, FM modulation and static noise. The crystal diodes used in the telephone can be divided into rectifying diodes (such as 1N4004), isolated diodes (such as 1N4148),

    I have 2 PWM ports, one generates 5V PWM and another at 3V. But only 1 will be generating at a time. However, their output is going to a same wire or pin. So, to avoid the current to pass into each other, I want to put diodes on each port as protection. For this, I would need fast switching diodes as PWM frequency is KHz or few MHz. I searched for fast switching diodes and found 1N4148. It does what I need but its forward voltage is 1V. So, for 3V and 5V, it will blow up ? or am I understanding the datasheet wrong ?
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    I read in this answer that forward voltage is voltage drop ? so if its voltage drop, whats the max voltage that it can support ? also 3V will come out as 2V, so I will be required to level it up to 3V again, right ?
     
  2. mozquito1

    mozquito1 Well-Known Member

    Would that forward voltage just turn to the 3v basically adding the 2v when switched on.
    Servos have an idle current of 0.2ma forward voltage, but can pull upto a max amperage of 3.8amps. So I'm not going to get what I need from my mateks 2000ma 5v out.
    So I need something that gives 8amps?
    Or can I use the the 5v@ 2000ma but the servo will struggle. Sorry to answer a question with a question but I couldn't tell an 1N4148 from the next thing. My Electronics is pretty basic & quad based. I can wire a house but when it gets to the maths of it I may aswell be stoned.
     
  3. Jackson

    Jackson USA member at large

    You can find schottky diodes with lower voltage drops, ~0.3V.
     
  4. LoneRCRanger

    LoneRCRanger Well-Known Member

  5. Tentoes

    Tentoes Well-Known Member

    I'm guessing they're there to protect the 3v pwm generating device from the 5v pwm generating device in a simple "OR" gate.
     
    mozquito1 likes this.

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