Re: [softrock40] Re: SP-70 Transformer performance?
- At 12:36 PM 6/29/2008, Pete Smith wrote:
>Yes, I did, Jack - I was very careful to make sure that the top of theHello, Pete and the group--
>windings (pins 1 and 3) went to the signal lines from the SoftRock and to
>the sound card, and that the bottoms (2 and 4) went to the common lead on
>their respective side of the transformer. I will double-check, because I
>have a history of this sort of mistake, but I don't think so.
>I did notice that the DC resistance of the primary and secondary are quite
>different - 72 vs 92 ohms. <snip>
I'm not surprised that he resistance windings are different. The
primary winding goes on closest to the core, and the secondary winding
gets applied next. However, the length of turn increases because the
secondary is physically further away from the core. Thus, the
primary might require 100 feet of wire while the secondary requires
140 feet for the same number of turns.
The manufacturer can use a larger-diameter wire for the secondary
winding, but the larger wire takes up more space and makes
it more difficult to get the required number of turns onto the core.