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Re: Any Bright Idea's?

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  • Jeff BAZ-man
    Hi Garth, true, the Reverse Voltage rating is normally about 5V but I never power 1 LED, usually 3 or 4 in a string (i.e. 15-20V PIV equivalent) so it has not
    Message 1 of 13 , Jul 31, 2009
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      Hi Garth, true, the Reverse Voltage rating is normally about 5V but I never power 1 LED, usually 3 or 4 in a string (i.e. 15-20V PIV equivalent) so it has not problem for me.

      On Z-Bend Track modules, there is a standard in place for Accessory Power. We have been using 12VDC as it is the most common source for all of our Accessories. Those with home layouts using a common power pack could either use a 4 lead bridge rectifier (the ~ symbols are the AC pins and the + /- pins are as they are - if the package is marked) or just a single diode (stipe end to the Red or + lead of the LEDs, preferably with the resistor somewhere in series with this side.

      Jeff
      SF Bay Area Z

      --- In z_scale@yahoogroups.com, "Garth Hamilton" <garth.a.hamilton@...> wrote:
      >
      > I think there are some caution notes required here. Standard LED's can be run on AC or DC but like a diode you have to know the PIV rating of the LED or Diode to be sure it is safe to use in an AC circuit. You still have to make sure the LED is current limited and it is the current that determines the brightness not the voltage depending on the LED and it design parameters.
      >
      > Many of the SMD LED's (Surface Mounted Devices) are designed for 3-5vdc and will not stand up to raw AC even with a current limiting resistor. This is why most SMD LED's are used with lighting modules in our trains which condition the power for the device. Essentially they limit the current and prevent reverse polarity reaching the LED making sure it receives the correct current/voltage regardless of the track power or polarity.
      >
      > Standard incandescent lamps are fine on AC or DC as long as the voltage limit of the lamp is not exceeded.
      >
      > cheerz Garth
      >
      >
      > --- In z_scale@yahoogroups.com, "Jeff BAZ-man" <sjbazman49@> wrote:
      > >
      > > No Rob, you do not need a bridge rectifier to run them off AC. The LED's are diodes but will only conduct half the time on AC so 'half' the brightness. 1k resistor will still work for the 14-16VAC Accessory terminals.
      > >
      > > Make life simple.
      > >
      > > Jeff
      > > SF Bay Area Z
      > >
      > > --- In z_scale@yahoogroups.com, Reynard Wellman <micron@> wrote:
      > > >
      > > > Hello Robert Ray,
      > > > Thanks for the specification requirements
      > > > for running the new streetlights. I also purchased a passel
      > > > of them from HongKong. Other lamps from Germany
      > > > came with resistors and are running brightly off the
      > > > Marklin 17 VAC terminals for one of my dioramas.
      > > >
      > > > I always run solenoid operated equipment using the AC
      > > > as well. Atlas momentary switches, no resistor required.
      > > >
      > > > Since others have been lauding the brightness benefits
      > > > of running lamps from a DC source, I will look into
      > > > purchasing a new DC supply, the 1K, 1/8W resistors. The
      > > > power supply will be dedicated to operating these HongKong lamps.
      > > >
      > > > best regardZ,
      > > > Reynard
      > > > On Jul 29, 2009, at 5:50 PM, Robert Ray wrote:
      > > >
      > > > > doerzm wrote:
      > > > >
      > > > > Can anyone provide simple instructions on how to do so? Not very
      > > > > electrically inclined.
      > > > >
      > > > > It's best to use a DC power supply to power these type lamps. If
      > > > > you have a 12VDC power supply, then a 1K ohm 1/8W resistor will
      > > > > work fine.
      > > > >
      > > > > If you have a 5VDC power supply, then a 470 ohm 1/8W resistor works
      > > > > great.
      > > > >
      > > > > If you plan on using the AC Accessory side of a typical train power
      > > > > pack, then you must use a bridge rectifier and a 1K ohm 1/8W
      > > > > resistor. Hook the 2 pins of the bridge rectifier marked with the
      > > > > squiggly lines (AC side) to the accessory terminals on your power
      > > > > pack, and the other 2 wires to the resistor in series with the
      > > > > lamp. If it don't light up, swap the lamp's wires around. It don't
      > > > > matter which lamp wire gets the resistor.
      > > > >
      > > > > -Robert Ray
      > > > >
      > > > >
      > > > >
      > > >
      > > >
      > > >
      > > > [Non-text portions of this message have been removed]
      > > >
      > >
      >
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