Transformer help

Minas transformers are typicallyy referenced by the nominal voltage output ratehr than the turns ration. A lot of them now have a pair of priamry widnings rated at 115V each. You connected them in prallel for 115V mains or series for 230V mains. The polarity _does matter_, it may be AC, but the relative phase is important. Most standard small transofmers have a pair of equal-voltage secondary windings. Again you can connected them in series or parallel if that's appropraite for what you are doing. The 'VA' rating is essentially a power rating. It's product of the ouput votlage and the maximum output current. So, for example, a '20VA' tranfromer with a single 4V secondary winding would have a maximum output current of 5A. Note that when there are 2 idnetical secondary windings (as is often the case for the mains transfomers we get over here) each winding has half the total VA rating. So a 20VA transformer with a pair of 4V secondaries would have a maxikum currnet rating of 2.A for each secondary. You could connect them in series ot get an 8V 2.5A AC supply or parallel to get a 4V 5A AC supply. Yo ucan always use a tranfoirmer with a higher VA rating than you think you need, but don't be ridiculous about it. If you need 9VA (say 9V and 1A), then you might fiud na 12VA transformer (a standard size over here) is easier to get. That would be fine. But don't use a 200VA one. It is too large, heavy, and expensive. What exactly do you need? If it's the 9V AC at 1A for a C64 supply, then you need a 9VA or higher transfoemr with some way of wiring it to give 9V. The 2 obvious candidates (and I think both are not too hard to find) would be a pair of 4.5V secondaries that you wire in series or a pair of 9V secodnaries you wire in parallel. -tony