The Lowspec spectrometer

[Thalestris24]

5 hours ago, Fellside said:

Hi

I`m right at the beginning of my Lowspec journey.

Can anyone tell me approximately how much material is required to print the Lowspec parts and what is the preferred material to use.

Many thanks

Graham

PLA has been fine for me. I would advise:

1) Calibrate your printer

2) Practice bed levelling

3) Get familiar with your particular printer. Do lots of practice test prints of rectangular pieces with holes in them to check how they come out and to be certain your bed is level  

Hth

Louise

[Fellside]

Louise and Jom 

Thanks for the advise. When you say a "whole real" is this a 1KG real?

Many thanks

Graham

[Thalestris24]

13 minutes ago, Fellside said:

Louise and Jom 

Thanks for the advise. When you say a "whole real" is this a 1KG real?

Many thanks

Graham

Yeah, filament comes in 1kg reels. I think my Lowspec 2 weighs around 500g including lenses and grating (it's actually 1.18kg with cameras and t2 tubes attached but my qhy183m weighs about 450g on its own). Exact weight will depend on the density you print at. How much you actually use is going to depend on whether you have to do reprints. I've had to reprint some of the parts 3 or 4 times... But I'm not an expert 3D print person! I was a complete 3D and slit spectrograph beginner when I started.

Louise

[Thalestris24]

On 02/03/2020 at 12:30, Fellside said:

Hi

I`m right at the beginning of my Lowspec journey.

Can anyone tell me approximately how much material is required to print the Lowspec parts and what is the preferred material to use.

Many thanks

Graham

Meant to mention before, there is quite a bit of useful info and peoples' experiences of printing and using the Lowspec on here

Louise

 

[saac]

On 02/03/2020 at 21:27, Fellside said:

Louise and Jom 

Thanks for the advise. When you say a "whole real" is this a 1KG real?

Many thanks

Graham

Graham, yes as Louise said above the standard reel is 1 kg.  I can't remember exactly but I'm pretty sure it was done on one  1kg reel.  Longest part to print was the main body that was over 2 days ! My printer has an pause print function which made it a bit easier but I was glad when it was finished. Be prepared to do a little bit of fettling on the internals to get them to fit exactly - small needle file comes in handy.   It's a great project to do -I'm still working on my optics.  Good luck if you decide to do it. 

Jim 

[Thalestris24]

3 minutes ago, saac said:

Graham, yes as Louise said above the standard reel is 1 kg.  I can't remember exactly but I'm pretty sure it was done on one  1kg reel.  Longest part to print was the main body that was over 2 days ! My printer has an pause print function which made it a bit easier but I was glad when it was finished. Be prepared to do a little bit of fettling on the internals to get them to fit exactly - small needle file comes in handy.   It's a great project to do -I'm still working on my optics.  Good luck if you decide to do it. 

Jim 

I just bought a Tacklife rotary tool off Amazon to help me with some 3D printing post-printing tasks. Yep, (needle) files are useful too. Having a cfl bulb is useful for initial testing as well as a neon. Building the Lowspec was my first ever experience of tapping a thread - better late in life than never! 🙂 

Louise

[Fellside]

Louise and Jom 

Thanks for the advise. Particularly the Astronomical Spectroscopy Group link Louise.

I still have not pushed the button on a printer yet. There are a lot of options to thing about.

Many thanks

Graham

 

[drjolo]

On 07/02/2020 at 13:03, Thalestris24 said:

Yeah, one of those would work to generate the voltage. The only trouble is that it's a dc-dc converter which means that only 1 half of the starter bulb will light which is why I've steered clear of them. That may not be a problem in practice, I'm not certain, but it may affect the life of the bulb and may affect it's behaviour. Certainly worth a try! 

Both Nixie tube converters arrived, both work, however only one meets our requirements. Output voltage in the first device can be set between 80 and 380V. I tested it with two Relco SC480 starters and they start to glow at 220-240 VDC, and optimal brightness is at 260-270VDC. There is 27 kohm resistor in series with the starter bulb (it can be two 47 kohm resistors in paralell). 

So this is the first one device:

This converter is okay

Second one is also regulated, but this regulation can be done in a range 100-230VDC, and that is too low. At 240VDC one of my starters just starts to glow, and second one does not even start. So when you choose Nixie tube converter, select the one that gives at least 270-280 VDC output.

This one gives too low output voltage

Remember to put resistor in series with the starter. Otherwise bimetal will be short in a few seconds, and the converter may be damaged. I left first one turned on for about 15 minutes and all was fine. 

Edited March 5, 2020 by drjolo

[Thalestris24]

1 hour ago, drjolo said:

Both Nixie tube converters arrived, both work, however only one meets our requirements. Output voltage in the first device can be set between 80 and 380V. I tested it with two Relco SC480 starters and they start to glow at 220-240 VDC, and optimal brightness is at 260-270VDC. There is 27 kohm resistor in series with the starter bulb (it can be two 47 kohm resistors in paralell). 

This converter is okay

Second one is also regulated, but this regulation can be done in a range 100-230VDC, and that is too low. At 240VDC one of my starters just starts to glow, and second one does not even start. So when you choose Nixie tube converter, select the one that gives at least 270-280 VDC output. 

This one gives too low output voltage

Remember to put resistor in series with the starter. Otherwise bimetal will be short in a few seconds, and the converter may be damaged. I left first one turned on for about 15 minutes and all was fine. 

If you can find the data sheet for the particular starter bulb you have it will quote a  non-reclosure voltage. For a Philips S10 'Ecoclick' 4-65W that voltage is 140V. So below that it shouldn't close the bimetallic contacts. I've bought a couple of EL power supplies which output 120V. I was hoping to use them without a resistor. However, I've not got around to trying them yet - they were very cheap so no great loss if they don't work. I also bought a white EL panel to maybe use for flats. I've also bought a nitrogen spectrum tube which might be better than a starter bulb as it has a limited spectrum but covers the visible range. I haven't got it working yet - I have to sort out a power supply that works. I think the tube needs around 2kV to strike. I have some power supplies (CCFL) and an alternative EHT one to try. Hopefully, will get around to trying them out soon 🙂. 

Louise

[Paul Gerlach]

7 hours ago, drjolo said:

Both Nixie tube converters arrived, both work, however only one meets our requirements.

Those look neat and compact.

[Thalestris24]

Well the EL Panel inverter powers the little EL panel I bought 🙂 

It does just power the starter bulb but maybe not quite bright enough. I'm not sure whether that's a current limitation or a voltage one. The inverter can also give an electric shock... 😛 

Panel:

 

Starter Bulb:

 

As I have two of the EL inverters, I might try connecting them in parallel to see if it's a current problem. On the other hand, at 120V the bimetallic contacts don't switch on and off.

I'll try out the EHT source plus a power controller with the nitrogen spectrum tube tomorrow. I know the EHT source outputs a very high voltage...

Louise

 

[Thalestris24]

Had the nitrogen spectrum tube running. I connected it up to a '400kV' 'Step-Up Boost Power Module' I got off Ebay. Input voltage was from a 12V battery via a variable DC-DC converter. The Boost module is supposed to run from a 18650 4.2V battery but I don't have anything that will properly control the 18650 voltage. 

Anyway, are a couple of YouTube videos I made:

1. Using a minimum voltage from the DC-DC converter:

 

2. Using a slightly higher input voltage:

 

Now I just need to get the Lowspec up and running again (I still have a problem with the guide platform 😞 I've reprinted it yet again but need to tap the holes and clean it up in order to get all the parts to fit together.

Louise

 

[saac]

I am a fair bit behind with my Low Spec spectroscope - I'm hoping to make some proper progress over the upcoming Easter holidays.  Anyway, I was messing about with it today and I had a trial to see if I could get focus.  I used a CFL  and then daylight ; still some way to go  -  I can't get proper focus , I think I need to get the camera (Starlight Xpress SXVR H9C) closer in to achieve focus I think.  That said, I was relatively pleased with this effort, tantalising glimpse of some Fraunhofer lines.    If anybody has any tips for focusing I'd be grateful to hear.   

Jim 

[Thalestris24]

3 minutes ago, saac said:

I am a fair bit behind with my Low Spec spectroscope - I'm hoping to make some proper progress over the upcoming Easter holidays.  Anyway, I was messing about with it today and I had a trial to see if I could get focus.  I used a CFL  and then daylight ; still some way to go  -  I can't get proper focus , I think I need to get the camera (Starlight Xpress SXVR H9C) closer in to achieve focus I think.  That said, I was relatively pleased with this effort, tantalising glimpse of some Fraunhofer lines.    If anybody has any tips for focusing I'd be grateful to hear.   

Jim 

Maybe not far off focus. The focal length is determined by the Lowspec camera lens. I got mine close to focus by measuring from the lens to the sensor plane to get the right T2 tubes between the camera and the Lowspec body. I've not found my Lowspec focuser easy to use - my one tends to be a bit stiff 😞 Oh, I added a rotator to get the camera sensor horizontal.

Louise

[Paul Gerlach]

1 hour ago, saac said:

I am a fair bit behind with my Low Spec spectroscope - I'm hoping to make some proper progress over the upcoming Easter holidays.  Anyway, I was messing about with it today and I had a trial to see if I could get focus.  I used a CFL  and then daylight ; still some way to go  -  I can't get proper focus , I think I need to get the camera (Starlight Xpress SXVR H9C) closer in to achieve focus I think.  That said, I was relatively pleased with this effort, tantalising glimpse of some Fraunhofer lines.    If anybody has any tips for focusing I'd be grateful to hear.   

Jim 

Jim,
the back focus outside the LowSpec (using the 100 mm lens) is about 51 mm (from the face of the threaded ring to the focal point and when the camera lens is placed halfway it's travelling distance). The SXVR H9C has a back focus of 17 mm so you'll need a spacer of about 34 mm. Or less if you also want to introduce a rotator.

Paul

[saac]

Paul thanks very much for that swift reply;  your drawing makes it so much easier to understand.  I think I'm only a few mm off as Lousie hinted at above,  but I had used all the spacer combinations that I had available.  I'll order up some additional extension tubes to give me  the 34  mm I need. Thanks again., Im really looking forward to using the Low Spec in school as a bench spectroscope as well as at home with the telescope   

Jim   

[Merlin66]

With the 51mm backfocus, the normal DSLR and T2 adaptor won't fit (needs 55mm), but there's a very narrow T thread to Canon adaptor available (only 1.5mm thick) which should work.

I think I got mine from Bern at Modern Astronomy.

 

[Paul Gerlach]

13 hours ago, saac said:

Paul thanks very much for that swift reply;  your drawing makes it so much easier to understand.  I think I'm only a few mm off as Lousie hinted at above,  but I had used all the spacer combinations that I had available.  I'll order up some additional extension tubes to give me  the 34  mm I need. Thanks again., Im really looking forward to using the Low Spec in school as a bench spectroscope as well as at home with the telescope   

Jim   

Jim, I could design a spacer that you can print. I've done that for my Atik 314L.

[Thalestris24]

5 minutes ago, Paul Gerlach said:

Jim, I could design a spacer that you can print. I've done that for my Atik 314L.

FWIW, I aimed to get my spacing to align close to the mid-point of where the focuser puts the lens. That gave me focusing leeway. Of course, it all changed when I swapped my camera...

Louise

[saac]

7 hours ago, Paul Gerlach said:

Jim, I could design a spacer that you can print. I've done that for my Atik 314L.

Thanks very much Paul, I've downloaded the T2 thread plugin that you made for Fusion 360 and I thought about having a go at making a spacer myself ( I'm still a novice at 3d modelling and printing) though.  Optics is something that I must admit I need to put a wee bit more effort into understanding but your drawing yesterday really helped. My lens is not your specified 100 mm fl rather its 95 mm (supplied from Surplus Shed)  I'm going to play around with it over the next weekend and if I can't get it working them I may come back to you and take you up of your kind offer.   I actually think I may ultimately have to get a different  (proper) lens from Thor lab - my lens  from Surplus shed is an un-cemented doublet. I fear that any misalignment may result in aberrations/shadows/reflections  - but I will play around before I make the decision.  Your drawing yesterday really cleared things up and I can now see what I have to measure.  I'll let you know how I get on.  

Jim 

Edited March 16, 2020 by saac

[Merlin66]

What's the latest status on the various LowSpec builds?

Been quiet for a while.

 

[Thalestris24]

9 hours ago, Merlin66 said:

What's the latest status on the various LowSpec builds?

Been quiet for a while.

 

I'm afraid mine's been put to one side for the moment.

Louise

[saac]

9 hours ago, Merlin66 said:

What's the latest status on the various LowSpec builds?

Been quiet for a while.

 

Mine is waiting for a replacement lens (camera) from Thor Labs.  I was close to focus with my original two element (two separate lenses not joined) lens (f95 mm) but I couldn't quite get it nice and sharp not even after playing around with spacers following help from Paul. I think the two separate lens may have not have been properly aligned. Anyway, the new lens should arrive tomorrow so hopefully I'll be able to post a nice sharp solar spectrum.  

Jim 

[Paul Gerlach]

Yes, it's been quiet on the 'LowSpec-front' 😉 but I'm still working on it.
I'm busy with a calibration unit for the LowSpec. I abandoned the idea of a unit on the side. Instead I want to build a unit that's more like the one the ALPY uses.
I also want to design a separate slit/autoguide unit. The idea is that these two parts can be reused in other future designs.

[Merlin66]

Paul,

If you can configure a reference lamp arrangement where you can "easily" switch from say Neon (Ha region) to the RELCO (Hb region) that would be great.

I think we both agree on the DIY need for a separate slit/ guider module.

Ken