Model Railway Forum banner

The ultimate DCC Power Supply

667 views 0 replies 1 participant last post by  VS-Admin 
#1 · (Edited)
The ultimate DCC Power Supply
"nec plus ultra"
by Doug Teggin - January 2006

I have a normal 16 volt AC transformer for my DCC layout. It does the job well, but I needed more power. I want to add further boosters, ensure a clean source of power for my point decoders and install 12V lighting circuits around the track. Looking around at prices of about ÂŁ36 for a 42VA (3amp) transformer and about ÂŁ47.50 for a 70VA (4.6amp) transformer, I realised that I needed 3 or 4 of these things, the bigger the better.

So I thought: Why not make one? So I did.

I found a plan on Huib Maaskant's site for a 6 x 16V AC power supply fed by a toroidal transformer with 2 x 16V / 10amp circuits (300VA).

Toroidal transformer

Product Human body Circuit component Font Automotive lighting


I modified his plan slightly. Original plan here: Pwrsply.pdf (78 kb). On my plan (below), I increased the main power fuse to 2.5amps and I added 1N4001 diodes in series to all of the circuit indicator LEDs to protect them better from the AC current.

Rectangle Slope Font Handwriting Parallel


I bought the components from Conrad, having to order a few times as you never get everything in one go. Hopefully this shopping list at the bottom of this page will prevent you from having to do that if you decide to build one of these yourself.

So here are the bits and pieces laid out.

Circuit component Drinkware Gas Electrical wiring Liquid


I first marked and drilled all the holes in the case. This was a bit of a mission as the box is steel and very hard. I suggest drilling a small pilot hole of about half the width of the final hole to prevent any issues with miss-aligned holes. If you need to drill a 12mm hole, get yourself a 12mm bit - don't do what I did and use a 10mm bit and an hour with a file...

Wood Tool Slip joint pliers Knife Fashion accessory


Here, the power connectors, power switch, the fuse holders and LEDs are fitted.

Electronic instrument Gas Audio equipment Rectangle Auto part


View from the other side.

Eyewear Vision care Wood Rectangle Gas


Behind the power switch, LEDs and fuse holders.

Wood Gas Audio equipment Hardwood Bumper


Everything wired up. Relatively straight forward. The wire I used was ridged household wire that gave some structural strength to the diodes and resistors. Note the toroidal transformer is bolted to the chassis. The box is earthed to the earth connector on the power plug.

Gas Auto part Engineering Audio equipment Cable


There is order to the madness... :)

Product Audio equipment Electrical wiring Gas Eyewear


Audio equipment Electrical wiring Circuit component Red Hardware programmer


So does it work?

Yes, I am pleased to say that it does. 16 volts across all the outputs. All working fine.

Musical instrument Electronic instrument Audio equipment Gas Machine


The multimeter checks the voltage. All is fine. The 1amp fuse on the mains power side of the transformer in the original plan by Huib Maaskant did blow as I expected it would. The 2.5amp fuse that I have added in the plan above works fine.

Audio equipment Electrical wiring Electronic engineering Gas Technology


When a device is plugged in to one of the circuits and the fuse is removed (or blows), the red LED for the circuit illuminates. It does not illuminate if there is no device using the circuit and that circuit's fuse is blown.

Toy Audio equipment Abacus Electronic instrument Gas


I'm very happy with this project. I was slightly worried that I wouldn't get it together as I have not built any circuits for a while, but it was quite easy. It is very solid and safe.

Shopping listCost
I bought the toroidal transformer on eBay from Antek (Antek's eBay shop)ÂŁ20.00
1 418250-62 RESISTOR 1% 0.6W 1 KOHMÂŁ00.21
1 418439-62 RESISTOR 1% 0.6W 33 KOHMS (added to the one above to make 34KOHMÂŁ00.21
12 418277-62 RESISTOR 1% 0.6W 1.5 KOHMÂŁ02.15
1 162248-62 DIODE 1N 4004ÂŁ00.07
12 162213-62 DIODE 1N 4001ÂŁ00.74
7 550825-62 FUSE HOLDER 6.4X31.8 MM. 6 XÂŁ19.22
1 068959-62 10 FUSE 6,3X32MM 2,5 AMP SLOWÂŁ01.51
1 068961-62 10 FUSE 6,3X32MM 4 AMP SLOWÂŁ01.51
1 521442-62 METAL BOX 300X102X195MMÂŁ15.76
4 523151-62 FEET ABS 21 MM FOR BOXÂŁ01.38
6 064580-62 INSULATED PLUG 4 MM REDÂŁ05.78
6 064581-62 INSULATED PLUG 4 MM BLACKÂŁ05.78
1 064464-62 DOUBLE THROW SWITCH ON/OFF 10AÂŁ02.68
6 730661-62 BANANA PLUG 4MM RED SCREWÂŁ04.33
6 730670-62 BANANA PLUG 4MM BLACK SCREWÂŁ04.33
6 184586-62 LED 5 MM RED CQY40ÂŁ01.24
6 184730-62 LED 5 MM GREEN CQY72ÂŁ01.44
1 184934-62 LED 5 MM YELLOW CQY74ÂŁ00.24
13 178942-62 LED SUPPORTS 5MM PLASTICÂŁ02.68
1 612600-62 POWER SOCKET 10A/250VÂŁ00.83
Total ÂŁ92.09

The rest of the components come from Conrad (Conrad France site ). I have noted that some of the reference codes do not work on the British Conrad site (www.conrad-direct.co.uk ) so you should perhaps look at the item and find a corresponding one from Conrad UK, Radio Spares or Maplin Electronics. The Conrad (France) code is highlighted.

So I figure that if I bought 4 70VA (4.6amp) transformers at ÂŁ47.50 each it would cost ÂŁ190.00

This 300VA (20amp) power supply cost just less than half that. So it's a good deal overall.
 
See less See more
13
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top