Patents for H04R 13 - Transducers having an acoustic diaphragm of magnetisable material directly co-acting with electromagnet (404) | |
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05/1978 | |
05/16/1978 | US4090041 Electromagnetic sonic generator for an alarm |
02/1978 | |
02/21/1978 | US4075437 Chromium, cobalt, iron, zirconium, aluminum niobium, and/or titanium |
04/1977 | |
04/05/1977 | US4016376 Concave diaphragm for electro-acoustic transducer |
03/1977 | |
03/29/1977 | US4015227 Electromagnetic transducer |