I'm doing a retro layout which needs DC control. I've got a number ECM Compspeed controllers lying about which I could use, but it would appear that all the old transformers I have stashed away no longer work !   Would they work with a modern power brick that gives smoothed DC or do they specifically need an AC supply ? The power bricks seem significantly  cheaper than buying a cased transformer.    I can't find any details of the circuit the compspeed uses to try and work it out myself.