Power box

I have made a "Power Supply Box" for use with any layout I eventually make. This is a plastic tool box, approx 390mm x 185mm x 170mm (internal), with all the mains supplies, transformers and voltage regulators built into it. It is also lockable for safety if used at exhibitions or outside the house with a portable layout. There are two cooling fans, one on each end, to help keep the equipment cool and running at a reasonable temperature. This has been monitored now the box is built and operating to see if any further cooling was required and all is fine over an extended operating session.

Power requirements are as follows:-

Mains 240v, UK style 3-pin socket - for Prodigy Advance
Mains 240v, UK style 3-pin socket - for soldering iron or other normal mains powered items
Mains 240v, US style 2-pin(flat) socket - for Prodigy Express. For this I have fitted a "Multi-use socket" which can take mains plugs from almost any country
Bare transformers - one has dual outputs, one has split output and one has a single output. These can supply either AC or full wave DC via bridge rectifiers or half wave DC via two diodes. They are as follows
1. Gaugemaster T1 dual 16v AC 32va - 1 amp per output.
  This powers supplies any combination as follows
  - 16v AC 1 amp - for anything that requires this type of power supply
  - Home built DC regulated supplies of 9v and two 12.5v (one for the cooling fans) with a suitable bridge rectifiers
2. 13.75 - 0 - 13.75 volt transformer, this is used, with a 5-pin DIN plug/socket as AC power supply the Fulgurex & Tortoise point motors via diodes. This means only one cable per point motor is required from the control panel so reducing the number of cables required. Only pins 1 (13.75v), pin 3 (0v) & pin 5 (13.75v) on the 5-pin DIN plug/socket are being used. Using two or three diodes in series will reduce the voltage at the motors and make them run both slower and quieter.
3. 11.2 volt 80watt transformer - use with a bridge rectifier for home built regulated supplies of 5v & 7.5v for layout buildings & yard lamps, turntable or point motors
Home build 5v, 7.5v, 9v and 12.5v DC regulated supplies which can be used to power lights in layout buildings & yard lamps, the Peco Turntable and the Fulgurex & Tortoise point motors if I did not want to go down the DCC route for point operation. Probably be the best option is DCC for the large loft layout and either manual rod operation or electric by switches for a portable layout.
Hornby C912 - 16v AC 13va mains plug-in type transformer. This can power 16v AC or DC regulated supplies as follows
- LS150 accessory decoders
- MRC 1628 & Gaugemaster DCC30 Accessory Decoders
- 16v AC 0.8amp - for anything that requires this type of power supply

The Power Box has the following power sockets available

240v Mains - one IEC-320 3-Pin C14 Male Euro Power Chassis Plug (on side). 110-250VAC, 10A - power into Power Box
240v Mains - one standard switched single socket (on front)
240v Mains - one standard un-switched single socket (on side)
240v Mains - one multi-national switched single socket (on front)
16v AC - using a 2.5mm DC socket
13.75 - 0 - 13.75v AC - using pins 1, 3 & 5 on a 5-pin DIN socket for slow motion point motors/li>
5v DC - using a 2.1mm socket
7.5v DC - using a 2.1mm socket
9v DC - using a 2.1mm socket
12.5v DC - using a 2.1mm socket
12.5v DC - internal for the cooling fans at each end of the Power Box

Low voltage requirement for either 16v AC or 5v, 7.5v, 9v & 12v DC items to be used on my layouts are as follows:-

MRC 1628 & Gaugemaster DCC30 Stationary Accessory Decoders. These need a 16v AC supply and they rectify their outputs to 12v DC so no seperate rectifier is required.
Lenz LS150 Accessory Decoders. These need a 16v AC supply.
Tortoise slow motion point motors. These need a Maxinumun of 12v DC supply which can be either full wave or half wave rectified. Typical power consumption is 14-16ma so a 16v AC 500ma transformer rectified will supply approx 30 motors. The voltage can be lower than 12v DC which will make them work slower but also quieter, 9v is probably about the best.
Fulgurex slow motion point motors. These need a Maxinumun of 12v DC supply which can be either full wave or half wave rectified. Typical power consumption is 200ma. Unlike the Tortoise motors they are not "stall" type and the power is cut off when the motor reaches its limit so no power is used when they are idle. The voltage can be lower than 12v DC which will make them work slower but also quieter, 7.5v or 9v is probably about the best.
Peco Turntable motor. I will try between 5v & 9v DC to see which is most suitable for this motor. I will try a selection of the DC regulated supplies to see the most suitable one.

I will also build a seperate variable regulated DC supply of 1.25v to 15v, using the twin 20v AC transformer mounted in the metal case, for bench repair work.

Hoefully this will cater for all the requirements of the two layouts and has made it futureproof!!!

Some photos of my Power Box - now it is completed

Here are photos of the ends of the Power Box showing the fans, the unswitched round 3-pin socket and the mains power inlet socket, main swithch and mains fuse. Also note the guards to keep little fingers out.

And the inside of the Power Box showing the sockets, fans, transformers and the five fused DC regulated power supplies. Any electricians looking please note that I am not an electrician but I do respect electricity and try to comply with the IEE regs.

This is the wiring diagram of the Power Box

Components used in the Power Box

Part No	Item	Qty	Additional Information	Make/Supplier
Transformers
T1	Transformer	1	Dual 16v AC 1 amp outputs - for Power Box 9v, 12.5v & Fan regulated supplies	Gaugemaster
	Transformer	1	11.2v AC output - for Power Box 5v & 7.5v regulated supplies
	Transformer	1	13.75-0-13.75v AC outputs - for Power Box split AC supplies
Bridge Rectifiers & Diodes
OF432/E7914	Bridge Rectifier	1	Bridge Rectifier - for Power Box 5v & 7.5v regulated supplies	Philips
KBL10	Bridge Rectifier	1	4amp 1000v Bridge Rectifier - for Power Box 9v, 12.5v & Fan regulated supplies	HVCA
Fuses & holders
Main 240v input fuse
	Fuse holder	1	10amp 250v for 1 1/4 x 1/4" (32 x 6.3mm) fuse
T3.15AL	Fuse	1	32x6.3mm - slow blow 10amp fuse
Transformer supplies and voltage regulator outputs
	Fuse holder	10	5x20mm PC board mount fuse holder	RS
KC01	Fuse holder	5	5x20mm Chassis mount fuse holder	Maplin
GJ90	Fuse	10	1amp 5x20mm - slow blow 1amp fuse	Maplin
Switches
GU55	DPST switch	1	DPST 16amp 250v red illuminated rocker switch for mains power supply	Maplin
GU51	SPST switch	3	SPST 16amp 250v red rocker switch for the three transformer supplies	Maplin
Plugs & sockets
C14	Mains socket	1	10amp 240v 3-pin C14 Male Euro Chassis socket
	5-pin socket	1	5-pin DIN socket
2.5mm x 9mm	DC power socket	1	2.5mm x 9mm (8mm hole) DC power socket 12v DC 3amp rated	Maplin
2.1mm x 9mm	DC power socket	4	2.1mm x 9mm (8mm hole) DC power socket 12v DC 3amp rated	ebay
	3-pin mains socket	1	Standard switched mains single socket
	3-pin mains socket	1	Multi national switched mains single socket - bought on ebay from Singapore	ebay
	3-pin mains socket	1	Inset 'circular' un-switched mains single socket - mainly for soldering iron etc
Misc items
A91CJ	Cooling fan	2	80mm ultra quiet case cooling fan	Maplin