Edgerton Lab Notebook T-1, Page 31:
April 11, 1930
- Page start date:
- April 11, 1930
- Content type:
- notes
- Transcription:
- Frequency Limitations of the Mercury Stroboscope
A General Radio oscillator was used to regulate the freq. Mr. Hall fixed up this circuit. It fed into the grid circuit same as the experiments of apr 5, except the neg. bias of the grid was varied to fit the needs of the oscillator. With 110 volts on the condenser freq. up to cyc. p.s. 1200 were reached with with fair definition of the line. This line was a radial white strip (about 1/8") on a 12" black disc. The disc rotated at 1200 r.p.m.
In the afternoon we put 220 volts on the condenser and varied the amount of capacity. For the high frequencies the constant of the condenser circuit were not fast enough for the stroboscopic action.
With a high voltage on the condenser more energy can be stored in the condenser and discharged more quickly (due to small capacity for equal light). However the resistances that blocks the circuit must be larger and thus the time constant of the circuit that charges the condenser is slower.
We showed I believe that this tube would gain satisfactory stroboscopic action from 20 cyc/sec. to 700 [+/-] cyc./sec.
A large Western Electric cone was excited with 150 volts 60 cyc ac. and the stroboscope was run at about 59 or 61 cycles. The surface of the cone could be seen to warp and oscillate at a slow speed. We could see the vibration patterns of the surface. Prof Borises saw this and was interested.
- Keywords:
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