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Old 7th Dec 2017, 9:06 am   #12
Argus25's Avatar
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 1,660
Default Re: Matched Transistors

Originally Posted by Neil Purling View Post
The audio stage transformers are probably rubbish anyway.
Thanks anyway for the discussion.
I think you are right there, especially the very small pcb mount transformers, might only be good for 35mW output if that. This is one thing I admire about very vintage transistor radios, they often had very impressive transformers in the audio.

Have a look at the transformers in the Pacemaker radio in figure 6 in this article, you can see the size compared to the 6V lantern battery. The driver transformer is the same size as the output transformer:

On page 7 of this Sony TR-72 article you can see the substantial transformers they used:

Naturally these radios sound wonderful, both had rear ventilated cabinets, like many Hacker radios.
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