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RPi + Other Software Level Shifter based MOS

Discussion in 'Hardware Support' started by azzuro, 7 March 2017.

  1. Biggles

    Biggles Member

    Messages:
    53
    Hardware:
    RPi1/Zero
  2. azzuro

    azzuro New Member

    Messages:
    18
    on my sketch you can see 4 wires, the max drop should be 0.38v with Full brightness, with my own calculator.
    but maybe my choice is bad, or my soldering is bad too, wasn't easy to solder 18awg on the strip.
     
  3. Akriss

    Akriss Active Member

    Messages:
    496
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    I used short, less then 100mm of 20 gauge leader wire to solder to the strip. I found that the thicker gauge wire increases the risk of damaging the solder pads if you snag a.wire.

    Hope it helps.
     
  4. penfold42

    penfold42 Moderator Developer

    Messages:
    750
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    262 leds at 0.06A is about 15 amps

    5m of 18awg wire will drop about 3v which is terrible:

    http://www.calculator.net/voltage-d...nce=5&distanceunit=meters&amperes=15&x=61&y=7

    Remember you lose voltage on both the positive and negative wires which could cause the data signal to be too high AND too low at the 1st led.

    You could use thicker wires for the 5m run and then a short 1inch wire at the end to make soldering easier
     
  5. azzuro

    azzuro New Member

    Messages:
    18
    hello,
    yep 15Ais the total current, but i have 4 wires who link the PSU to leds . so we can sayeach channel can take 3.97A at full brightness.
    Voltage drop: 0.83
    Voltage drop percentage: 16.60%
    Voltage at the end: 4.17

    http://www.calculator.net/voltage-d...=5&distanceunit=meters&amperes=3.97&x=93&y=10

    i will try to use the data wire for connect the +5v on psu too !
    for reduce the number of led on it.

    but the best will be to have 16AWG instead of 18. :mad:
    with my calculator the dropvoltage was good on 18 AWG, but you own not
     
  6. penfold42

    penfold42 Moderator Developer

    Messages:
    750
    Hardware:
    RPi1/Zero, RPi2, RPi3, 32/64bit, +Arduino, +nodeMCU/ESP8266
    Cool - is that 4 power and 4 ground wires ?
     
  7. azzuro

    azzuro New Member

    Messages:
    18
    yep !
    4x +5v / GND ( directly from PSU)
    1X +5V/GND/data/clock ( from PSU and RPi )

    And forgotten i have an wire behind the TV who make an loop of the gnd.for connect the last led to the first. for reduce the drop on ground and bypass the gnd on strip for the dataline.

    but for now, my best result is mosfet level shifter.
     
  8. Rick164

    Rick164 Administrator Staff Member Administrator

    Messages:
    190
    Hardware:
    RPi2, +Arduino, +AtmoOrb