last nights attempt at M51 with 1100D

[DrRobin]

Hi,

Excellent, you got there. Looks like your two transistors are load sharing quite well and if you can keep your finger on them, they must only be getting to around 50 - 60 C, that is my limit anyway.

If you ever want to go higher and still get a smooth output (variable voltage, variable current limit) I would go to a PWM (class D) design. You will probably know all about class D from your Synth/Amp/Music background. Power PWM is a little different, but the concepts are the same. For any given output, the heatsink will be much smaller, but you do need to watch the smoothing.

I designed a small PWM PSU with voltage and current limit some years ago, built a prototype and then never finished it. I did look to see if there are any desings on the web, but drew a blank after a quick search, although I am sure there would be something.

Anyway back to Astronomy, it was clear last night, but I noticed from my Night Sky camera it didn't get properly dark until after midnight and it started to get light again at 3am. I am going to give DSOs a miss for a couple of months.

[todd8137]

very nice ,and great color

[Gina]

I designed a small PWM PSU with voltage and current limit some years ago, built a prototype and then never finished it. I did look to see if there are any desings on the web, but drew a blank after a quick search, although I am sure there would be something.

Yes, I've searched the web before for PWM PSUs but also drew a blank. Using a reasonably high frequency should ease the inductor problem but I believe you do need inductive smoothing. I feel a new thread coming on

[mindburner]

hi Robin

I am dying to get out for some AP. The perfect antidote to the daily grind. Yes it's after midnight before it's dark and then 3 hours later the sun's up. Still good for getting the likes of the dumbell. You should have a shot at that with the edge. Would look great.

I actually had the 12 incg dob out a few nights ago. Moon as up but had a look at Saturn and it was superb, with lots of detail.

As far as the PSU goes. I am glad it;s finished. I can now sell y little Lascar supply.

[DrRobin]

Hi,

I am having a little bit of a break from DSOs for a couple of months until we get some darker nights. If it is clear on a weekend, I might have a go, but I am just too busy at work to stay up half the night mid week.

[Gina]

I've pretty much given up for a while too but mainly it's the weather. We get slightly longer nights down here but the nights are still quite short so any imaging does entail waiting up and staying up until the small hours. I'm just slowly sorting some of my equipment out and doing final touches to my obsy.

[DrRobin]

Hi,

Mindburner is just a little further north than me, (I think) but a lot further west so it gets darker much later, probably about 20 minutes later, still dawn is 20 minutes later as well. Gina, you probably get around 30 minutes more night than us and you aren't suffering from all of these North East winds bringing rain and mist that we are enjoying at the moment.

Going to give the Dumbell a try if we get a clear weekend night, as well as M101 and M66, that will probably be it until August. I will give the moon another try next full one and the sun when there are interesting sun spots.

[Gina]

We have been getting quite a lot of rain and winds, some torrential rain, and a lot of cloud. I am definately suffering from SAD!

[DrRobin]

11pm here, just back from taking the dog for a walk. About 50% cloud cover, no stars visible, it's just too light. I mean not one with the naked eye. Roll on Autumn.

[Gina]

We seem to have a reasonably clear night here First time for two months, so I'm making use of it. Capturing subs of the Iris Nebula. I'll post results later.

[michael.h.f.wilkinson]

Really superb. This kind of image has me itching to get myself a DSLR and attach it to my little 80mm.

[DrRobin]

Hi Gina,

Hope your session on the Iris Nebula yielded some good results? 11:25pm, just back from taking my dog for her last walk of the day. Only a handful of bright stats visible, yet the is almost no cloud here. There is nothing visible to the north at all. In fact if I draw a line from west to east passing straight overhead, there isn't a single star visible north of that line and everything that is visible is south of the line. That's the problem with the sun being only 20 degrees below the horizon.

[mindburner]

I was hoping that the weather would be clear for the weekend but it's not looking likely. My problems is that if I don't use it I loose it and spend time trying to get back to where I was some months earlier.

[Gina]

I was hoping that the weather would be clear for the weekend but it's not looking likely. My problems is that if I don't use it I loose it and spend time trying to get back to where I was some months earlier.

Oooh I know just what you mean Just been lucky to have one and a half clear nights after two whole months of cloud and/or rain! The first (half) night was spent sorting myself out and getting my scope lined up, mount adjusted etc. Then last night I was more back into things and managed a couple of hours of imaging. I was able to get lined up on the Veil Nebula while it was getting dark so ready for proper imaging by midnight when it was just about dark enough. It started to get light about 2am so I packed up doing lights, parked scope, closed roof and set up for darks which I left running while I went to bed.