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A mechanical phase locked loop!
On 05/08/2017 22:24, rickman wrote:
Gareth's Downstairs Computer wrote on 8/5/2017 3:14 PM: On 05/08/2017 20:06, rickman wrote: Yes, because it *is* a PLL. In fact the problem most people have with it is that it doesn't adjust the phase by adjusting the frequency of the slave. It adjusts the *phase* so clearly it *is* a phase locked loop. All pendulums have circular error where the frequency is determined by the amplitude of swing, All *uncorrected* pendulums have circular error. The Fedchenko clock has a mounting spring for the pendulum that corrects for circular error. Hadn't heard of that one. At the BHI lecture there was mention of another correction of circular error by a colied spring attached somewhere at the bottom, but I wasn't paying full attention at that point. There were also other means such as cycloidal cheeks around the suspension spring. so for the half cycle where the phase is adjusted by abridging the swing by the hit of the hit and miss stabiliser, the frequency of the slave is, indeed, changed. This has nothing to do with the circular error. It has everything to do with the circular error and the variation in frequency that comes with varying amplitude of the swing. The standard formula given for the cycle time of pendulums .. 2 * PI * root( L / G) ... is only valid for those small angles where sin( theta ) = theta, and such angles are so infinitesimal that no visible movement of a pendulum would be seen! This equation is an approximation which ignores the higher terms of the power series of the full equation. It is only truly valid for no swing at all. .... which is virtually the range where sin( theta) = theta. |
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