kbrown

Just out of curiosity I tried my cheap Canon 50mm f/1.8 as an eyepiece. I think I managed to attach it to the 2" focuser directly without adapters. It worked great but hasn't had much use since I don't really do visual observing.

51 minutes ago, Dr_Ju_ju said:

I have made & use my own, using heavy duty waterproof material, but they are a bit heavy and cumbersome & over time the material has a tendency to 'crack' allowing seepage...

I've recently also started using one of these https://www.ebay.co.uk/itm/313611338500  which are much lighter & quick to deploy. 

 

Thanks for the tip. I'll look into those a bit deeper.

Even with the cover I still probably would be assembling and dismantling the kit as per need and not just leave it outside 24/7 365. Just need some temporary cover for a week or two of clear sky spells...

Looking for ideas for a telescope cover. Has anyone made one? What garment/material did you use?

I'm toying with the idea of designing and sewing one together to cover all of this with some weatherproof material:

I have seen some commercial covers available but they're rather expensive and I have no idea whether they would fit. I do have a heavy duty (good enough for denim/leather etc) sewing machine so I'm tempted to make use of it and go creative...

8 hours ago, Len1257 said:

That's your problem then. Constraining the size is a restriction you are placing upon yourself. You could easily re-hash the physical layout to make it more thermally efficient.  Your flat minimal height layout isn't helping at all. Then making it out of plastic is another shot in the foot.

This is what I use.  Nevada Power Supply Note how the case is the heatsink. You can buy thermally efficient finned aluminium cases in all sorts of sizes.

Maybe your underlying problem is actually your battery. If it drops below your quoted 12.5V and it's a lead-acid one then maybe look for one that holds up better under load like a suitably rated LiFePo4 one? When I'm away from home I use a 36Ah one that easily lasts a full night supplying my rig.  Definitely a more expensive solution and the battery managment system will chop the supply off if you should exceed it's minimum voltage. Can't remember offhand how far my volts drop though, I'de have to dig my notes out.

Yes I know the enclosure is a bit constraining. But height wise there isn't more room available where I want to have this sitting. I'll see if I can find a suitable aluminium case. At very least I could easily replace the existing lid with an aluminium one and perhaps have the Q4 mounted on it.

Nonetheless I managed to get it run a bit cooler by lowering the +19V at the booster output down to +17.2V. Still seems to perform well under load. I also added a 15uH 10A choke before the input caps and that seems to help with the interference to other devices.

10 minutes ago, Mandy D said:

Obviously, as others have said, more cooling is required for your pass transistor (TIP35). You have 5.4 volts across that transistor and up to 1.5 amps collector current. By my reckoning, that is a dissipation of 8.1 watts. For a comfortable rise of 50°C, that requires a heatsink rating of 6K/W.

You note that adding more capacitance to the input and/or output does not improve things. If you want to continue with this design of converter, I would suggest proper input and output LC filters, rather than just capacitance. So, a choke (inductor) in between pin 1 of J1 and the filter capacitors and similar on the output side will improve your situation.

I don't think it's quite 5.4V across the Q4 as the capacitance multiplier circuitry before the regulator stage lowers the 19V down a bit but I get the point. Have to probe what's actually going into the regulator stage at C3. I'll play around with some chokes tonight as well. Thanks for the tips!

1 hour ago, Len1257 said:

Not sure that you need all of that circuit complication but.............

Linear regulators always generate heat, nature of the beast. Get a fan in there at least. The old 'standard' heavy current supplies we used in our 1970's mini computers at work had multiple 2N3055's in parallel with suitable sharing resistors. But I guess your heat issue is the heatsinks in your photo look positively puny with a constrained air flow. Better to get a heatsink that can be bolted to a wall of your case with fins to the outside and mount your Q1 and Q4 with insulated mica's to that. Something like a Fischer Elektronic SK48 65 x 20 x 50mm at 2.8C/W or equivalent. Some on Ebay £6.39. I would have looked for one that maybe was wider with room for two devices and spanned across the side of your case. Lots of choice out there. Rapid Online Heatsinks have lots of variety. Else get a PC fan!

Not sure if I can get any bigger heatsinks in the enclosure which is pretty much at it's maximum size already. Maybe a thin laptop style cooling fan...  Think I'll build everything again from C3 towards right on the schematic on a breadboard again and see whether I can find a solution that would naturally run a bit cooler under load.

Been testing this a while now and while it works; It's not without quirks...

Originally I was going to power just the CCD with the power conditioner. But I also wanted to get rid of the cable clutter running to the scope so I divided the 12V input between the power conditioner and other (direct) outputs which I have connected to various devices on the system. By doing this I encountered an unexpected side effect: When the CCD cooler is working hard it occasionally draws a lot of current momentarily. While this is not a problem at the output of the power conditioner, it does show up as a voltage drop at the input (i.e. the other direct outputs as well). The drops in my case last only about 100ms but it does go down to something like 9.5V. This manifested as flickering on my flat panel for example...

First I tried adding more capacitance at the input and output but this didn't really fix the problem. In the end I ended up connecting all the devices to the power conditioned output. Everything works fine and is stable but I'm now drawing more current out of the device than I really wanted to. Below is my current circuit. While it works my concern is the Q4 getting a bit too hot. It's a TO-247 package with roughly a same size and 6mm thick heat sink on top of it. But it still gets too hot to touch under load.

Are there any electronics gurus out there who could give me tips on how to get this circuit to run a bit cooler? Perhaps my Q3/Q4 transistor choices are not the best here?

Brilliant. I had completely forgotten about those. I've two of them already so no need to send. Thanks for the kind offer though!

Title says it all. Does anyone know of a good quality and flexible (silicone preferably) USB3 Type A to Type B cable around 2m long? The average cables I have are very stiff especially when they get cold. Just trying to relieve the strain on the connectors and prevent the cables catching anything on a moving scope...

Have a look at my focuser project, if you're interested in controlling it with INDI (Ekos/Kstars): http://knowhere.myqnapcloud.com/WordPress/2021/09/04/bullseye-diy-focuser/

Very nice! Well done! Is that battery a deep discharge lead acid battery? If it's a normal car battery then I'd keep it topped up frequently to prevent sulfation.

15 hours ago, rsarwar said:

Hi. I am in the process of making one as well. 

For led strip I am using these 13cm Diameter Backlight Panel 
https://a.aliexpress.com/_mMybhPc

It means there is an inverter I have to include along with a rpi pico to control it, but the light from it is well balanced I think.... Have to confirm, item still on its way. 

 

Still going to use a defuse to mitigate hots tops or lines

Yes, EL panel is probably the better choice for better flatness. But it does require more electronics and isn't so easy to control brightness with.

I'm still tweaking my setup and haven't been able to verify whether my design is good enough yet or not.

+1 for FreeCAD. It's not perfect and does have a bit of a learning curve but it's pretty capable once you get used to it.

18 minutes ago, tomato said:

I do have room for one in my warm room but I was raised in the realm of machine tools, and I would still prefer to machine a piece of billet rather than extrude plastic filaments.

I'm by no means an experienced machinist but I started off with a desktop CNC router. I still have it and use it occasionally but since I got my 3D printer it has proven to be much more versatile for my purposes.

Maybe you could print housings for the bearings and then add thin teflon strips as the mating surfaces?

Suppose if you can just print everything then it would be easier and faster to put together? I'd probably use bearings though...

I like using V-Coil thread inserts.  So far I've been using all sizes between M2 to M10 and they always just work. For for example M3 thread I would simply model a 3mm hole which typically ends up printed a bit smaller. I'd print it with at least 3 perimeters. Then just use the drill bit and tap in the V-Coil kit to get the hole prepared for the insert.

Watching with great interest. I haven't progressed much with my version. Too busy with other things.

Originally I thought of NTC thermistors too but with them you need to take into account wire lengths or go with 3 or 4 wire configuration. That's why I decided to use digital sensors instead. Drawback is more coding involved and the poor Nano has very limited ram.

I'd be scared to put a 3D printed part in such a critical spot. Even with 100% infill you'll still risk a failure with layers coming apart. 

43 minutes ago, Dr_Ju_ju said:

If you truly want a clean output voltage, instead of using a "switched" supply, with its' inherent switching noise, I'd suggest a linear supply, based around a toroidal transformer, bridge rectifier etc.....

That is true. But I'm running things off a car battery hence the need to boost the voltage for the Atik. Wish I had a RoR obsy...

Hi,

Thought I'd share some first results of a project I've been working on for some time. The background to this is that I have an Atik 383L+ CCD that does not like low supply voltage. There's been numerous posts online about how its noise levels go up, when the supply voltage goes down. Some say this starts happening already below 12.5V!

My original remedy to this was to get a cheap XL6009 chip based DC-DC boost converter to keep the voltage at steady 13.5V and to be honest things worked okay. But at some point I had a look at what the voltage actually looks like under load with an oscilloscope. As you can guess it wasn't pretty. The more current you draw the higher the ripple voltage.

So after studying the subject a bit and testing things on a breadboard I came up with this device:

There's basically three stages in this:

1: The XL6009 DC-DC Boost Converter pumping up the input voltage up to 19V.

2: A Capacitance Multiplier circuit to significantly reduce the ripple produced by the boost converter. Similar to the top half of Figure 4 on this page.

3: A hight current LM317 based linear voltage regulator similar to Figure 23 on the LM317 datasheet page 17 except that mine isn't adjustable. It's set to about 13.6V.

Here's a test of the Capacitance Multiplier stage. The red channel shows the ripple on the output of the DC-DC booster which is 620mV Peak-to-Peak while drawing about 1A into a dummy load resistor. The yellow channel shows the ripple after the Capacitance Multiplier stage at the same scale. A massive difference!

Now that I've got everything put together, I have been testing it with the Atik 383L+ set to cool -30C below ambient for about an hour or so. The cooler is at about 67% power and drawing occasionally up to about 1.5A but it varies a lot. Average is probably about 1.1-1.2A. And since it's not purely a resistive load, the ripple is also very different:

Above you can see the ripple after the DC-DC converter (yellow) is a whopping 2.5V Peak-to-Peak! Yet the ripple going into the camera is only about 140mV.

There are a couple of drawbacks: The system isn't very efficient. If the camera is drawing 1.5A, the PSU could be drawing something like 2.5-3A occasionally! This means that things do get a bit hot. Overall I'm quite happy with the result anyway. I'll be taking new dark frames soon. Be interesting to see whether I see any difference to my old ones

Old thread I know but as someone just asked for the STL files I thought I'd update this thread as well. Originally I milled the threads onto the adapter after printing. This was only because I didn't realise you could actually print the thread. I modified the 3D model to include the M48x0.75 thread so you should be able to just print it with 0,1mm layer height or so. Attached are the stl files.

EOS_ClipFilterAdapter.zip

Been working on this motorised flap flat panel for quite some time already. Thought I'd finally post something about it as I just got the flap opening and closing properly for the first time. I initially designed this around the 28BYJ-48 stepper but that just turned out to be too weak. I did manage it to make it move by converting a 5V version to bipolar mode and driving it with 12V. But as soon as you removed power the gravity would take over and the flap would be a bit too flappy...  Keeping the motor energised continuously would have made it too hot over time and it probably would have not lasted very long so I decided to go with a high torque servo instead. This one is using a Hiwonder LDX-227 servo. Seems plenty strong for this application.

The flat panel itself is still work in progress. My original idea was to shine the light straight to the edges of the diffusing perspex but that didn't work out very well so I started experimenting with other ideas. At the moment the LED strip ring is hidden behind the diffusing perspex and reflecting off a reflector (aluminum foil on a concave surface). To the eye it looks pretty flat but if I take a photo of it and stretch the levels, you'll start to see a bit of a gradient. Whether this is a problem, I'm not sure... More about this later...

Sorry for the delay in answering. Only just saw this. Here's what I was able to find. Hope it helps:

TripodTray.zip

Hi guys,

Decided to upgrade the NEMA17 version of my focuser from direct drive to a timing belt system for my WO FLT91. More information on that and a video of it in action can be found here:

http://knowhere.myqnapcloud.com/WordPress/2022/04/21/bullseye-diy-focuser-upgrade/

Enjoy...