Big power supply

A big layout demands a big power supply. This is especially true for digitally controlled layouts. A power supply with insufficient power will show a decrease in voltage when a lot of power is needed. Also, sudden demands in power will cause spikes in the voltage level. This is not good for digital components. Of course one can buy a number of Märklin transfomers. These are expensive and can provide only a limited amount of power. Fortunately you can easily build a strong power supply yourself.

These are the schematics of a simple power supply for digital units or lighting. The power supply is constructed around a transformer of 2 x 16V/10A. The total power it can supply adds up to 320W and that is well enough to run 32 locos at the same time. If that is not enough, you just add another power supply. The low price makes that easily affordable.

How does it work? The transformer supplies 16V AC. Any transformer will do. The current is divided over six outputs. Each output is protected with a 4A fuse. A green LED shows if an output is working. A red LED shows that an output is connected to a load and that the fuse has been melted or switched off. This may indicate a short-circuit. The blue LED indicates that the power supply is switched on. The blue LED is connected to the mains via a little circuit (available from Conrad) to reduce the voltage.

The finished power supply, in this case with four outputs. On the front you will find the mains switch, the LEDs and the fuses. The connections are all at the back and use screw-on terminals. Take care when building a power supply! You are dealing with 220V - 240V. Do not forget the fuse in the mains connection. If you use a metal housing, the housing must be grounded and the power supply must be connected using a power plug with ground terminals.

The Dutch firm Amplimo offers suitable toroidal transformers. They can even deliver a 300 VA/16 V transformer for 115 Volts by special order, but you can also settle for a 15 Volts version. You can order the other components from Conrad or any other electronics store.

2001