| Electronics > Projects, Designs, and Technical Stuff |
| Transformer impregnation: paraffin + rosin + natural wax |
| << < (3/4) > >> |
| Gyro:
Well if it's a signal transformer that's not dissipating power and not in a hot environment, then the simpler the better. I remember plenty of '60s stuff using simple wax, eg. Candle wax. If you want decent impregnation without a vacuum chamber then you need something with a low enough melting point that you can safely immerse and heat the transformer to allow air to naturally bubble out of the windings. Wax (heated in a water bath) seems to fit the bill. P.S. I wouldn't expect any impregnant to have a significant enough impedance to affect the 'feeling' at audio frequencies but it would at least be soft enough to damp any winding / core vibrations if that's what you mean. |
| Conrad Hoffman:
The transformer may not get hot on its own, but don't forget the total environment. I think they were using varnish in the '60s, at least for better stuff. Probably have to go earlier to find wax, though I've seen a few telephone coupling transformers with wax or something similar. |
| vk6zgo:
It makes a bit more sense, being for an audio transformer, as, apart from standard "Telephone company" types, which were made in the millions, (& were not wax coated), full sized audio transformers were made in much smaller numbers than power transformers, so may well have used such techniques. I have seen, used, & messed about with, power transformers from late 1920s units to present day types, & I can't recall any using wax coatings. Power transformer manufacture is a mature technology, & the insulating materials & varnishes they used back in the 1940s, '50s, & '60s were more than capable of,doing the job they were used for. Most of the failures I have seen were open circuit windings, or windings with shorted turns. These are usually from severe overload, which would cook any modern transformer equally badly. |
| Gyro:
There's clearly a lot of overlap - I've certainly seen wax used in IF and output transformers (and to damp microphonics in the FM coils) in '70s transistor radios. I guess it depends what the OP means by a signal transformer (and as you say, Conrad, the temperature of the overall environment). I'm not sure if varnish automatically means vacuum impregnation? It certainly seems to be the case with modern polyurethane types. |
| 001:
--- Quote from: Gyro on September 07, 2019, 09:32:15 am --- I guess it depends what the OP means by a signal transformer (and as you say, Conrad, the temperature of the overall environment). --- End quote --- It is transformer in grid circuit of vacuum tube 1:20 I see similar wax-look transformers in common tube radios 40 year ago --- Quote from: Bud on September 06, 2019, 07:53:22 pm --- --- Quote from: 001 on September 06, 2019, 12:40:23 pm ---it is signal transformer of some audio gear wax increase bobbin capasitance and it adds "authentic" feeling --- End quote --- Authentic feeling to the sound? :-DD --- End quote --- Why not? It is customer demand so I must make it as described. Lets customers be happy :-+ |
| Navigation |
| Message Index |
| Next page |
| Previous page |