I've played around with transformers for a while now and I noticed that it doesn't seem to be possible to switch them to between there two EU outputs. Instead I've seen high voltage transformers not emit any power at all unless you send it a redstone signal and the resulting EU seems to be only 512 EU/tick. This behavior extends to low voltage + medium voltage transformers too; they won't emit EU unless given a redstone signal. In my tests I attached a EU storage block to the transformer, then some cable to it's output and fed into a second transformer and that transformer was connect to a second storage block. That setup always seems to require redstone to emit EU.
I didn't notice anything in the changelog about this, so I'm supposing it is not intentional. Has anyone else encounter such behavior from transformers?