On Sun, 25 Aug 2013 14:44:55 +0100, charles
wrote:

In article ,
Dave Plowman (News) wrote:
When building a split rail low current PS with discrete components - like
say +/- 15v - does it matter if the transformer doesn't have a centre tap
on the secondary? It's just that I've seen circuits for both around. Some
say to omit the centre tap connection to ground even if it has one.

It depends on what you are trying to power. If the device simply wants a
30v supply, then the centre tap isn't needed. If the requirement is for
+15, 0, -15 then you are going to have to get the 0 reference from
somewhere. It can be done in the load device with suitable circuitry, but
it's much easier to use the centre tap.

The question is a bit too genralised. What's the purpose of the PSU?

What design[s] did you have in mind for the circuitry?


A CT transformer may not be needed, but why not ask for some equally
relevant information such as the type of mains switch or colour of the
box you want to put it in?

AB