Gina

Priorities... nuts!!!  Need a break from all the hard stuff

Decided the month advance bar that turns the days-in-the-month wheel looks wrong across the 31 days wheel so I'm thinking of taking it across the bottom, clear of the 31d wheel.  Here is a rough diagram.

I quite fancy getting back to this project but unfortunately it has a lower priority...

Looking at thingiverse the other day I came across an illuminated moon globe that looked just the thing for the moon phase globe for this clock.  It's 140mm diameter with craters etc.  This would be a bit bigger than the moon in my moon phase clock which is 100mm diameter and should suit the bigger clock.  Glowing Moon  Worth a try, I think.  Probably try natural or white PETG or ABS.  It would be nice to have a moon globe with a bit of detail on the surface if I can get it to work

With this fascinating mechanism it seems a shame that it will be stationary most of the time - only operating at midnight and only doing "clever" things at the end of 30 day months or Februaries.  And it will only be me that sees it.  It seems a lot of work just for that!  A practical perpetual calendar could be much simpler - all the "perpetual calendar" data is already in the RTC module and it only needs stepper motors to drive the drums.  With the Arduino RTC library all the data is easily read out and could simply be arranged to control the stepper motors that drive the drums.

It seems to me that my time might be much better spent on other things.   While the perpetual calendar was going to be part of the longcase clock it made sense as everything would be mechanical but on its own I don't think it does.  OTOH I guess this mechanical perpetual calendar is almost finished and may take less time and effort to finish than starting again.

Well I didn't but I have done a bit of thinking...

Since I have the back focus sorted out for the 55mm lenses I think I shall go with those for my first dual imaging rig.  I need to have the minimum to do so as to be ready ASAP in case of a clear night (oh the optimism!! ).  I'm hoping I shall feel well enough to get on with things soon.  ATM I'm only doing what's necessary.  I keep looking at my projects to see if I feel up to making any progress.

For extending the bass response this would do me nicely :- The Epicenter 500 Subwoofer

Having a job to shift this cold and still not up to doing much which is making me feel depressed.  It's better than it was but still have a bad cough and just can't manage much

Assembly of turntable.

Here's the photo series from assembling the turntable.  The drive belt is supplied installed around the platter pulley (underneath) and a red ribbon is tucked under it.  This ribbon is used to pull the belt out and onto the motor pulley.

Here is a list of the equipment I have to date :-

1. Audio-Technica AT-LP3 Turntable.
2. Pioneer A-209R Amplifier - secondhand
3. Yamaha NSF51 Floorstanding Speakers - Black

Sometime in the future when funds permit I may buy a sub-woofer  such as :- Yamaha NS-SW300 sub-woofer - review here

Being much older and less capable with my hands I felt I wasn't up to positioning the pickup by hand, even with the ability to lower the arm hydraulically.  This led me to go for an automatic deck rather than a fully manual like I had before.  I had reservations about an automatically controlled tone arm but knew that buying online would enable me to return the deck and get my money back if i wasn't satisfied and maybe buy a fully manual one.  I needn't have worried - I am totally delighted with the deck I bought.

I found the sound quality of analogue reproduction was smoother and cleaner than digital.  As a scientist and engineer I couldn't see a logical reason why analogue should sound any better than digital - sampling rate and resolution both seemed more than adequate and yet I have found the analogue sound definitely better than digital having done a direct comparison.  I wasn't satisfied to take other peoples views on this I wanted to see for myself and now I have I'm totally convinced.

Now I have resurrected my interest in playing music and I'm really enjoying it.

A friend asked my to see if I could fix her record player and amplifier setup, which I did.  I had already decided it was time I started listening to music again to relax and this prompted me to think about my own vinyl record collection.  I have a number of records that haven't got a CD version and that I would like to play.  My original hi-fi system got partly lost and partly damaged in a house move and a few years ago I tried buying turntables but didn't find any that worked well enough so gave it up as a bad job.   This time I decided to buy a reasonably high quality turntable and make a proper go of it.

I might have abandoned this project as not being worthwhile in view of the amount of work required to get it to work but for two reasons - several of my friends are very interested in this project and also that I don't like to just give up

Having found that the pendulum won't synchronise unless the period is already very close to correct, it seems that some sort of period adjustment is required anyway.  In vintage clocks this is usually a thumbscrew on the pendulum bob to move it up or down.  Adjusting the other end is equally valid.  This could be manual or servo controlled (automatic) and I like a clock that looks after itself   Now since it seems that a servo controlled period could do the whole job of timekeeping it seems unnecessary to use magnetic synchronisation as well.

The above approach differs from my previous idea which was to manually adjust the period until close enough to synchronise by mechanical levers etc. from the auto-winder.

Thinking about pendulum timing control servo system, it might be worth doing this in two stages viz. coarse and fine :-

1. Measure the cycle time and adjust to make it 2s.
2. Compare pendulum phase with RTC phase and fine adjust to produce synchronism.

All this can be done with the Arduino I'm already using to drive the auto-winding system.  The mechanism for controlling the pendulum length could be a threaded rod driven by a stepper motor.

Been looking again at slave clocks and those with pendulums seem to use solenoids mostly.  In my clock design I have been using levers and a spring running off the auto-winding mechanism which is timed from a Real Time Clock module.   Magnetic drive to the bottom of the pendulum might be better.

Another possibility I was trying before was to vary the effective pendulum length by lifting the steel spring support while still holding it in the gap.  This shortens the pendulum and reduces it's swing time.  I could measure the swing time and control the lift with a servo system until the swing time was exactly 2s.  I have worked with servo systems in the distant past and used to know all the maths involved including damping coefficients    I have a horrible feeling that I might be past that now!  What I don't want is an unstable system that deviates more and more from correct timing

Looking back at where I got to before, I see I didn't even get the clock to run continuously without any timekeeping control so on a practical level (when I get back to it) I shall need to produce a decent escape wheel and get everything set up for a running clock.

Since posting last I have made good progress on the "GinaRep Mini" 3D printer but most projects are on hold until I shake off a heavy cold.  Also, this project has to take a back seat to astro projects and I need a calendar more than another clock - the Moon Dial Clock is working fine.  OTOH while I'm resting with this cold there is no reason why I shouldn't think about this project and after a considerable break I may have some new ideas :D. 

I have one serious problem with this pendulum clock - the pendulum and escapement.  I can't expect to make a perfect time-keeper with just a weight driven pendulum clock - even the most expert clock maker has not achieved this, so synchronisation to a true source of perfect time is what I have been trying to do.  So far I have not achieved this.  I know I need to make a better escape wheel but also I need to sort out a workable way of driving the pendulum from my time source.  Slave timepieces have been made in the past so I see no reason why I shouldn't be able to do the same.

The Pentax-M 28mm f2.8 lens arrived today - very good condition   Fits the adapter I bought for it too   Now I just need to find the EOS-T2 adapter that I bought a while back for another lens

I checked focus with the M42 screw mount 28mm f3.5 lens and it was on the limit - may need a bit more spacing.  I've ordered a 12-16mm adjustable T2 extension.  I checked the spacing and I reckon 14mm would be about right.

Let's look at a calculation...  Back focus of M42 is 45.46mm.  Back focus of camera is 6.5mm.  We want 45.46mm plus 1mm for Astrodon filter = 46.46mm.  So distance from lens to camera faces wants to be 46.46-6.5 = 39.96mm.  ZWO EFW is 20mm so about 20mm of extension wanted.  Since the lens moves forwards for focussing extending the spacers required the extension required with EFW is 20mm+ depending on the lens focal length.  The 28mm only moves 3mm whereas the 135mm lens moves 13mm.

I've managed to get both of these lenses to focus on the distant horizon within their focussing range by swapping extension tubes around.  Since these are 55mm the longer focus lenses should be alright.  I have yet to check the 28mm f3.5 lens and the 28mm f2.8 lens has a Pentax K mount which will need an adapter or two so I don't yet know about that.

Been trying the cameras for focus and despite the calculations I can't get focus on either of them - one is past the infinity setting and the other is past the nearest setting.  There is something very odd going on here as both imagers are correct by calculation and camera to lens distances match within a fraction of a millimetre.

Been sorting out extension tubes and rings for Asahi Pentax M42 lenses and the ASI1600MM-Cool cameras, one with ZWO EFWmini, the other with fixed filter held inside the 11mm extension ring with ZWO adapter (supplied with camera).

Back focus of M42 lens is 45.46mm.  Back focus of camera is 6.5mm.  We want 45.46mm plus 1mm for Astrodon filter = 46.46mm.  So distance between the faces of the lens and camera wants to be 46.46-6.5 = 39.96mm.  ZWO EFW is 20mm so about 20mm of extension wanted and the full 40mm (approx.) for the other camera.  Since the lens moves forwards for focussing extending the spacers required, the extension required with EFW is 20mm+ (and 40mm+ without) - depending on the lens focal length; longer FL lenses move more.

Here is a photo of the dual rig with 55mm f1.8 Super Takumar lenses.  All the M42 thread mount lenses have the same back focus so should be fine with these extension tubes/rings.

I guess I made reasonable use of this month's clear night but I seem to be a bit further away from being ready for imaging than I thought.  I think for the auto-focus to work properly I need finer focussing which can be obtained by a higher gear ratio and micro-stepping of the stepper motor.

Well, I think I've just about had enough for tonight and I don't think I can achieve much more ATM.  I need to sort out the focussing and I think I can do that in the daytime using a distant tree or trees.