Small model train layouts can get by with the basic transformer that comes with many starter train sets.

Remember, that a starter train set transformer probably doesn’t have a lot of extra power, and may not have a circuit breaker to prevent burn-outs.

If however, you’ve purchased a locomotive that doesn’t have a strong engine, then this type of transformer may be all you need to get started.

The transformer that comes with a typical starter train set (rated as low as 7 volt-amps, or just 0.7 amps delivered at 10 volts) will run one (maybe two) locomotives at the same time.