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ORD-20 20 Amp booster for DCE, DCC232, DDX and SPAX

**Very important issue**

Peter Giling developed a large number of useful pc-boards, all made for self assembling.
This self assembling will include the fact that the assembler / installer of these units must confirm CE regulations, and will be hold responsible for any problem that occurs.
As long as this installer is the only user of the assembled units, there is hardly no problem,
but as soon as other people are involved, one should be aware of that.
Almost all designs by Peter Giling stay below 42 Volt and max 3 Amp, which makes CE regulations pretty low level.
But his unit is made to supply up to 20 Amp, so be very careful with that.
Peter Giling cannot be hold responsible for any mistake in design or installation.
If you are not sure to follow the CE recommendations and/or regulations, please refrain from construction of this unit.
Though the pcboard as stand alone is available now, in a very nice quality, self construction might be a bit too dificult,
because you will need a test unit to be sure short circuit and overload protection are working properly. That is why the ORD-20 will be available as completely build and tested unit. All you have to do is creating a nice housing for it.

The professional board is made

The board has extra thick copper layers, but still need some
addional 1,5 mm² (+/- 15 AWG) wire-bridges
These pictures show 13 wire bridges at top-side
and 3 wire bridges at the bottom-side

And the tested end product is here

The ready assembled unit

Description

So far ORD-3 did a good job, but the limit of 3 Amp is not suitable for larger setups.
Though a chain of several ORD-3 booster is the perfect option for HO/TT/N-scale, it is not the ideal situation for G/1-scale.
Trains in that scale need a higher supply to get all functions properly working.
That is where this booster is coming in.
So far these high current boosters are quite expensive, but ORD-20 offers you a much cheaper way.
It is basicaly just a booster, without integrated supply as with ORD-3.
This is chosen because self construction of these high power supplies is rather complicated.
And there is a wide market of 20-30Amp power supplies available.
Big advantage of using an -off the shelf- power supply, is also that these power supplies can be set to a certain maximum current output.
This limits already a lot of problems with this high current.
The booster consists of High Power P- and NFET transistors.
All inputs, including CDE Lenz connection are isolated by opto-couplers.
There is no isolation between the individual inputs, which is hardly needed,
because only one input will be used at the same time.
Still, adjusting the advised power supply to the max of 20 Amp for this unit is not adequate enough.
If the current will be overrun, the power supply will control back to the max of 20 Amp, but still the full 20A will run through the short circuit.
That is called welding, and we do not want that.
The first issue is to have the power suply available for far more than 20 Amp.
Then max current out is et on that supply to 23-24 Amo, just as a safety measure.
Now, the ORD-20 itself can shut off on overload of approx 21 Amp.
Avoiding short circuit is of course the main issue here, but accidents happen, unfortunately.
Therefore, a current sensor is also implemented, to be sure the booster shuts OFF when 20 Amps are exceeded.
Automatic switching back on will be done in the same way as with ORD-3.
Unit just waits 5 seconds after shut down, and then try to restart again.
If short circuit is still there it will time out again for 5 seconds.
The time the max current will flow is less the 10 milliseconds.
The sensor for that is a low resistance shunt, to avoid too much heat on the pc-board, and also too much loss of power on higher loads.
5 Volt supply on board was original a simple well known 7805 linear regulator.
But since the latest version is also running with 24 Volt, the heat in this regulator was unacceptable.
With approx 100 mA for the total 5 V current this regulator was consuming (24-5) x 100 MA = 1,9 Watt.
A TSR 1-2450 switching regulator also solved that problem.
Despite the use of very efficient N- and P-Fet power transistors, the rather small cooling is getting pretty warm on full load.
I cured that by installing two small 40mm Fans 24V.
To avoid people to start complaining about the noise, I also included a small processor and a temperature sensor.
This will avoid that there is any noise when booster is running on low load.
At the same time I drilled a few holes right in front of the shunt SH1.
This very little airstream is enough to keep the shunt on a decent temperature.

Thanks to a lot of solar cells on my roof, I was able to keep the booster on full load (20,7 Amp 24V ) for hours, without
really being 'environment unfriendly'.
Booster is an absolute hit!

Features

  • Compatible with Spax Booster (Fremo)
  • Input for USB / RS232 / LocoNet Railsync / CDE (Lenz)
  • Short circuit / overload protected
  • Digital DCC driving directly with Rocrail DCC232
  • Galvanic isolated from all inputs
  • Prepared for RailCom cut out (so far hardware only)
  • Power input between 15 and 24 V dc.


Input examples

  • Rail connection of any standard central station ( connected to C and D of CDE1 connector).
  • Serial (COMx) port from any PC when using DCC232 in Rocrail (connected to RS232 connector).
  • Some USB to serial cables are useable in the same way like previous line.
  • Instead of RS232 connector, a direct USB connector could be mounted, which will work!
  • Useable as Spaxbooster, which includes the standard three RJ12 LocoNet connectors.
  • Booster connection on Intellibox or Twin center.
  • Just ask Peter if you have questions on this matter.


Led indications

Led colour Function (when lit)
L1 red Booster off
L2 yellow Input signal OK
L3 green Power on


Hardware files

Availability

So far all units were made for self construction.
But this ORD-20 is not an easy job for everyone.
And since it also needs a very serious check on load on shut off functions,
it is better to deliver it completely assembled and tested.
So no construction kit is available.

ord-20-en.txt · Last modified: 2018/11/26 02:55 by rainerk