Electronic Circuits and Projects Forum

Are you using the 24VAC to make a rectified and filtered +32VDC and 0VDC? Then there is no negative voltage.
Maybe your center-tapped transformer also made a rectified and filtered positive DC voltage and 0VDC with no negative voltage.

Your transformer data sheet will tell you the color code for the wires. I don't know that there is a standard for the color code, so check the makers data sheet. But to answer your question about the center tap, you connect the wires of the right color together for a center tap.

Originally Posted by irishape

I am making up a power supply for an amplifier I intend to make. I thought I would use an toroidal tran. It is a 230/115, 160va, 48v on secondary to be used in a parallel form so as to get two 24v leads. It will be parallel on the primary also which will use the 115v supply. My question is where do I get the neg. for the secondary as four of the secondary wires are jumped so as to use the parallel circuit. I have used a regular tran. that was center tapped and the central wire being neg. made it easy. On the sec. of this tran. it has four wires , black, orange, red and yellow. Bk. to Or and Red to Yel. gives me the two 24v leads. Help on the neg.? Thanks, IA

You use a 4 diode full wave bridge rectifier to get your negative. Like this;


The four-diode rectifier circuit shown to the right serves very nicely to provide full-wave rectification of the ac output of a single transformer winding. The diamond configuration of the four diodes is the same as the resistor configuration in a Wheatstone Bridge. In fact, any set of components in this configuration is identified as some sort of bridge, and this rectifier circuit is similarly known as a bridge rectifier.

It sounded to me like you were looking to make a + / - supply using your transformer. This would go better if you better explained exactly what you want the output to be and had a link to the transformer data sheet.

While the color scheme is not the same note the dots on the attached images, if you want a dual + / - supply it would be wired per the attached last image. This assumes you want a dual supply, if not the previous schematics are what you want.

Ron

I didn't know that you are making a plus and minus power supply because you said you were connecting the secondaries in parallel.
In series, their connection forms a center-tap.