13-01-2018, 03:02 PM
We used to fit RS 'Boost' transformers in TVs, either to isolate the heater in the rare cases of breakdown of the heater/cathode insulation or to boost a flat tube to get a bit more life out of it.
These had mains powered primaries and were designed to have a very low capacitance between windings.
I did though once come across an anonymous boost transformer in a set that came to us which was just an auto-transformer inserted in the heater chain. No use for isolation, of course, but I would imagine a much cheaper solution for the usual boost function.
As I say, the maker was anonymous and I only ever saw that one example.
Auto-transformers were also widely used for running US 117V kit off 240V mains. Woe betide anybody who also thought they were buying an isolating transformer because they weren't!
These had mains powered primaries and were designed to have a very low capacitance between windings.
I did though once come across an anonymous boost transformer in a set that came to us which was just an auto-transformer inserted in the heater chain. No use for isolation, of course, but I would imagine a much cheaper solution for the usual boost function.
As I say, the maker was anonymous and I only ever saw that one example.
Auto-transformers were also widely used for running US 117V kit off 240V mains. Woe betide anybody who also thought they were buying an isolating transformer because they weren't!
