A Handy Headphone Matching Unit

[Terry]

With me, it is no longer an obsession, and I only gain pleasure from experimentation, trial and error, and the theory can "go hang!"     I can go for weeks or months without even thinking about radio.  

I don't think anyone who posts here does anything in this field other than for pleasure, so I'm with you on that.

However, a lot of the information in this thread may well be of use to someone else of limited technical knowledge who is considering doing something similar.

"In any closed circuit of constant temperature, the ratio of voltage applied, to the current set up by that voltage is constant.   That constant is known as the resistance of the circuit!"  

I think the version I was taught is easier to understand: "When the temperature is constant, the potential difference across the ends of a resistance is proportional to the current flowing through it"

I would guess that this version precedes yours as it seems to have been written before the names of Volt, Ampere and Ohm were defined and adopted.

Many learn Ohm's law without the first part relating to temperature - or choose to ignore it - which they can later find very puzzling!