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.
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!
|Led||colour||Function (when lit)|
|L2||yellow||Input signal OK|
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.