Vintage Synth Repair

Hi

 

You make a statement that     <A 15V transformer with a non-connected
secondary will measure around 21 volts>             this is not necessarily
true!

 

It will depend solely upon the design of the transformer.  For example
choose a lower Gauss value, increase the amount of iron, increase the wire
gauge for both primary and secondary and you will have very much improved
regulation and the difference between no load and full load may only be a
volt or two.

 

In terms of regulation a laminated core of Is and Es will generally be
better than a toroidal core.  The reason for this is that you can get larger
wire gauges onto laminated types than on a toroid where you have less space
to play with.

 

In a word it is all down to the impedance.  Lower the impedance and improve
the regulation.

 

Regards

Brian G3OYU