New month, old set. Struggled a bit today and I’m not sure why, but I did make it to fifteen reps before my first fail and then failed again on twenty-one before swimming the set out.
USRPT distance this year: 135,800m
Total distance this year: 138,350m
I’ve used a couple of these power supplies for a few years for powering my NEQ6 and HEQ5 telescope mounts, but recently one of them just stopped working. It has been sitting in the workshop for a fair while waiting for me to do something about it and I recently “rediscovered” it, so I’d see what I could do.
Measuring the output voltage gave me something that was floating between about 9.5V and 11.5V, so I decided to open it up and see if anything obvious had failed. It has gained a few cobwebs and a bit of corrosion on the transformer core whilst it has been in the workshop.
Behind this board is at least one power transistor, and down on the base of the unit is the rectifier:
This is what I assume must be the regulator circuitry, though strangely it has an AC feed from the transformer. It has been suggested to me that it might be to feed some sort of circuit that senses when the unit is connected up, if it were to be used as a battery charger. There are plenty of components marked on the board that aren’t present, certainly.
And finally a couple of chunky smoothing capacitors.
I was expecting that perhaps one of the electrolytic capacitors might have given up, but actually they all look ok from the outside. Someone recommended that I twiddle with the two trimmer pots on the board in case they’d got failed, and to give them a bit of a clean so I did my best with that and powered the unit up again, at which point it gave me a nice steady 14.5V output.
So, the next step is to turn the voltage back down to 13.8V and see if it stabilises there. If it does then I think I’m done. Otherwise it doesn’t look like a particularly difficult job to replace the two trimmers as long as I can find out what values they need. A decent clean out probably wouldn’t hurt, either 🙂
Last swim of the month and it was completely chaotic. No lanes in the pool, people getting in the way everywhere, all a bit messy. I think I had two failed reps, but it was honestly hard to count it as a worthwhile session.
USRPT distance this year: 134,100m
Total distance this year: 136,650m
Hopefully when the sky is next clear at night I can get around to polar aligning my mounts, but before that I wanted to align the finders and main telescopes so I dug out an illuminated reticle eyepiece that I have mostly used to align targets for planetary imaging. I’ve had it quite some years and it’s very similar to the Skywatcher one:
It has a number of issues however.
The thread on the adjuster at the top of the eyepiece is quite loose and allows the top to wobble quite a bit. I found that (quite) a few turns of PTFE tape around the thread took a lot of the wobble out. I think that should be sufficient now as it feels fairly firm when the crosshairs are in focus.
The on/off switch isn’t great either. It also wobbles, and more often than not I forget to turn it off after using it. The knob is held on with a grub screw, so I undid that, pushed the knob on as far as I could and re-tightened it. That has improved the wobble, though it’s a little more stiff now.
I also discovered that it no longer works. Unscrewing the LED barrel revealed a couple of possible reasons:
I cleaned up the corrosion on the battery contact with some fine emery paper and resoldered the broken wire. Pleasingly that was all that was required to get it working again.
I am quite tempted to look at some means of fitting it with an external power supply. Having it plugged into a cable might actually make it easier for me to remember to disconnect it from the power. I need to give that some more thought though.
A more interesting day today, as whilst I was warming up someone who used to be a member of the club appeared on poolside and asked if she could join me and do my set (there was only one lane set out and I was the only one in it, so not an unreasonable call). She’s not swum much for the last six months and as it turned out we were reasonably well-matched in terms of speed over the set. I’d been hitting around 47s for most of the reps and before the last one she said “Push hard and go 46s on this one.” So I did, and touched the wall on 43s plus a few tenths, which I think is the fastest I’ve ever done a rep whilst swimming this set, regardless of target/turnaround time.
Two reps missed again, on thirteen and twenty.
USRPT distance this year: 132,400m
Total distance this year: 134,950m
An addendum to my previous design post. The builder dropped the motor units off for the stair lifts that he thought might be butchered to make an automated roof mechanism.
This first is the lighter weight one for the rack made from multiple steel plates. The pinion wheel here is the same.
The second is for the solid steel rack. This one also has lots of microswitches that are undamaged and might be useful as limit switches.
For the moment however they’re going to remain on one side. I want to get all the existing planned work completely before adding more. I just need to bear it in mind for the wiring and so on.
No swimming on the Monday thanks to the bank holiday, but same set again today. For the time being I think I’m going to keep these postings short unless there’s something new and interesting to report.
So, fails on reps fourteen and twenty today.
USRPT distance this year: 130,700m
Total distance this year: 133,250m
Ok, so this was accidental, but I’m sure it counts 🙂
I found it whilst reviewing frames for my last star trails image. I’d seen a meteor that night and wondered if it was caught on camera, but didn’t initially find it when I ran through the original frames. Only when I went back through them again looking for aircraft trails did I spot it. Sadly it wasn’t entirely in the frame, but as it was only caught by chance I’m not going to complain.
I got a couple of hours out in the observatory after dark and set up the 450D again to capture some subs to make a star trail image. This is better than the previous night, but I’d cut the exposure time down to try to reduce the sky brightness, not realising that either the camera or APT had reset the ISO setting when I was setting up the focus so there aren’t as many stars as I’d have liked. The good news is that even without a hood, the dew heater appears to have worked and kept the lens clear for the entire duration.
However, what really interested me was the diagonal trail at the left hand edge.
At first I thought it was a meteor. I definitely saw at least one, though I can’t be sure those I seem to catch out of the corner of my eye aren’t just odd reflections off the lenses of my glasses these days 🙁 Looking at the individual subs it’s certainly way brighter than the aircraft trails that pass overhead, but it definitely looks man-made. It actually starts much fainter, appearing from behind the barn roof in this first crop:
And continues the same way in this next one:
There appear to be white spots alternating either side of the main red line, which makes me think it has to be some sort of aircraft. And in the last frame it appears on, this happens:
It wasn’t until some time later that it occurred to me to have a look at the flightradar24.com site, but of course then it was too late. Or was it? Clicking around the site I discovered it has a “playback” mode that allows a review of earlier flights, even from previous days, so I played back events around the timestamp of the image.
It turns out that a flight from Faro to Cardiff passed within two miles east of me at just over 7,000 feet at exactly the right time according to the timestamp on the image. I feel sure that has to be the explanation. Perhaps the sudden increase in brightness is down to landing lights being turned on or something like that.
As the rest of the family has been seeing the observatory slowly being constructed over the last year and we had some clear sky I thought I’d have a go at something fun to show them now I’ve reached the point that it’s usable (though some way from complete), so I set the 450D up on a tripod with the kit 18-55mm lens wide open, pointing back at the house with the intention of taking some subs to combine into a star trail image.
Sadly the clouds didn’t appear to have read the forecast and the five hours of clear sky I was promised turned into an hour or so of mostly clear sky, and the cloud was worst to the south west — the direction of the house. So this is all I ended up with:
Perhaps the most interesting thing about it is that there are no lights on in the house at all. The lit windows are all illuminated by power indicator LEDs on chargers, clock displays and suchlike.
It’s not all negative though. I’ve been visual-only for quite some time whilst we’ve been having work done in the house because it made sense to pack kit up to keep it out of the dust, and during the construction of the observatory, so this is my first image of any kind in a fair while.
I did also grab some frames looking back over the observatory towards Cassiopeia, but struggled with the lens dewing up. I don’t have a hood for this lens which probably doesn’t help (and in fact the ones I’ve found online don’t look as though they’d be much help anyhow). I might try a dew heater, or attempt a 3d printed hood of my own. I should also have a go with my 14mm Samyang, though I suspect that will be even more prone to dew.
