Coiled spring door closer, by J. Pearson, c.1890 Coiled spring door closer, by J. Pearson, c.1890 1890
Coil about 240 turns No. 28 S.W.G. aluminium wire to suit gap but with tripod broken away, part of Oliver Lodge’s microphone amplifier or relay, 1898 (British patent 9712 of 1898) ), a precursor of the moving-coil loudspeaker Coil about 240 turns No. 28 S.W.G. aluminium wire to suit gap but with tripod broken away
Circular coil used with Transcranial Magnetic Stimulation (TMS) machines Circular coil for Transcranial Magnetic Stimulation machine
18.5 turn aluminium strip coil to suit gap with wooden tripod support, part of Oliver Lodge’s microphone amplifier or relay, 1898 (British patent 9712 of 1898) ), a precursor of the moving-coil loudspeaker 18.5 turn aluminium strip coil to suit gap with wooden tripod support 1898