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"The JMST" — a quest to restore a 1974 C8 by a telescope newbie

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#26 RSX11M+

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Posted 17 February 2021 - 02:02 PM

I just ordered a 12v-110ac sinewave inverter - let me check it out with my scope before I provide the info. It's ~$50.

 

My concern is how accurate the 60hz is. - will advise



#27 davidmcgo

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Posted 18 February 2021 - 09:18 AM

Orion Dynamo mini works fantastic with my Questar and vintage Celestrons.

 

https://www.telescop...ord=Dynamo mini

 

Dave



#28 RSX11M+

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Posted 18 February 2021 - 05:06 PM

I have been looking for an inverter with programable variable frequency. I want it to do the various astronomical rates, or at least a close approximation. Since so many of the vintage scopes use synchronous motors, one would think this would be more commonly available in the era of everyday microcomputers. (maybe it once was)  

 

I keep hoping I'm just missing it, but I don't find anything new with the sophistication or precision I would find compelling.

 

I may end up making something out of an Arduino and parts. It has to have voltage-regulated AC sinewave output, but doesn't need a lot of power. (200w-500w should do) Better to use two cheapies and have a spare than one big expensive unit. Did some basic research in this direction a few months ago, but have to write myself a spec if it's to go further.

 

JMST could use one, if it was available. Otherwise just power is a start. On a whim, I tried calling Bestek to chat about the precision of their freq standard - no answer. Bought one to check it out. Will advise-


Edited by RSX11M+, 18 February 2021 - 05:55 PM.


#29 CartoonOwl

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Posted 19 February 2021 - 01:06 AM

Responding to this in a meaningful way requires me to know, or assume, where you live on the planet - generally.

 

I'll take a stab at "North America" or USA.

 

In this locality, the most important view for astronomy purposes is Polaris (North Star), and an unobstructed view South.

 

All the Planets appear in an east-to-west arc across the sky to the South.

 

A view straight up, while useful, is not as important. Is this a small courtyard? Can you get a Polaris view at all by moving to one end or the other? What about the South?

 

Lets see if your equipment works before we get into all that deeply. - But it is coming.

 

Update:

 

Do you have a small computer UPS handy? I've been meaning to try one out with my Sand cast C8 - maybe I'll do that for giggles.

I'm in Los Angeles, and the courtyard is very small. I mean it when I say I can only get a view more-or-less straight up, because as I get closer to the edges of the building I get too much light. So I'm going mobile (It worked great on the solstice when I got nice views of the conjunction and just manually fiddled with the knobs once a minute) The question I was asking was about how to power him if I'm taking him out in the car to more open views. These battery packs you guys are suggesting with plug-ins or just a good old-fashioned UPS will do the trick. But first, I have a wire to deal with grin.gif



#30 CartoonOwl

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Posted 19 February 2021 - 01:07 AM

I have been looking for an inverter with programable variable frequency. I want it to do the various astronomical rates, or at least a close approximation. Since so many of the vintage scopes use synchronous motors, one would think this would be more commonly available in the era of everyday microcomputers. (maybe it once was)  

 

I keep hoping I'm just missing it, but I don't find anything new with the sophistication or precision I would find compelling.

 

I may end up making something out of an Arduino and parts. It has to have voltage-regulated AC sinewave output, but doesn't need a lot of power. (200w-500w should do) Better to use two cheapies and have a spare than one big expensive unit. Did some basic research in this direction a few months ago, but have to write myself a spec if it's to go further.

 

JMST could use one, if it was available. Otherwise just power is a start. On a whim, I tried calling Bestek to chat about the precision of their freq standard - no answer. Bought one to check it out. Will advise-

Ooh, this is the part that's a bit over my head. Am I going to blow something up if I power this wrong? Myself, perhaps? Realistically, though, am I going to ruin something in the mechanism if I power it wrong, and how likely is that with zero prior knowledge about wiring?


Edited by CartoonOwl, 19 February 2021 - 02:14 AM.


#31 RSX11M+

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Posted 19 February 2021 - 05:46 PM

Ooh, this is the part that's a bit over my head. Am I going to blow something up if I power this wrong? Myself, perhaps? Realistically, though, am I going to ruin something in the mechanism if I power it wrong, and how likely is that with zero prior knowledge about wiring?

1:07AM huh? Your ARE a Night Owl.

 

Short Answer: Nope, nope and ... nope.
 
The long explanation is - too long. Basically, objects cross the night sky at slightly different rates than... the night sky passes.
 
In tech talk - Lunar rate is slightly different from Sidereal.
 
AC bases (aka "Clock Drives") had to be designed to do the best for the county they are to operate in. This is why some motors are made for 50Hz and others for 60Hz.
 
However, the variation in frequency to deal with ideal tracking for an object is very slight. You won't hurt anything in your equipment - it's just that objects won't stay centered as long if the rate isn't ideal.
 
So the "perfect" AC inverter for astronomical use would let us select the AC rate for our need, or even take input from a "guider". 
 
Hopefully I haven't over explained this.

 

Basically - if you can plug your scope into a wall outlet, you should be good to go on an inverter.


Edited by RSX11M+, 19 February 2021 - 05:54 PM.


#32 CartoonOwl

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Posted 19 February 2021 - 05:55 PM

Nope, nope and ... nope.
 
The long explanation is - too long. Basically, objects cross the night sky at slightly different rates than... the night sky passes.
 
In tech talk - Lunar rate is slightly different from Sidereal.
 
AC bases (aka "Clock Drives") had to be designed to do the best for the county they are to operate in. This is why some motors are made for 50Hz and others for 60Hz.
 
However, the variation in frequency to deal with ideal tracking for an object is very slight. You won't hurt anything in your equipment - it's just that objects won't stay centered as long if the rate isn't ideal.
 
So the "perfect" AC inverter for astronomical use would let us select the AC rate for our need, or even take input from a "guider". 
 
Hopefully I haven't over explained this.

No that's perfect. It makes me profoundly less nervous about plugging this beast in, because chasing objects with the fine controls is nowhere near as scary as frying it or myself. But it also tells me enough to understand what particulars you are discussing about the power supplies and why.



#33 RSX11M+

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Posted 19 February 2021 - 06:07 PM

I'm in Los Angeles, and the courtyard is very small. I mean it when I say I can only get a view more-or-less straight up, because as I get closer to the edges of the building I get too much light. So I'm going mobile (It worked great on the solstice when I got nice views of the conjunction and just manually fiddled with the knobs once a minute) The question I was asking was about how to power him if I'm taking him out in the car to more open views. These battery packs you guys are suggesting with plug-ins or just a good old-fashioned UPS will do the trick. But first, I have a wire to deal with grin.gif

Yeah, I'm responding out of sequence.

 

I'm glad you explained this. I was thinking we might be able to mark your courtyard so is wasn't necessary to see Polaris to get a good alignment from the ideal place for your scope. If the building has so much light pollution that you can't escape it in the courtyard at all, thats another thing. (short of erecting a temporary local barrier around your viewing spot)

 

An AC car inverter is a good approach. An ideal car inverter for astronomical use - is less important in the beginning, and is mostly what my other post's ruminations are about.

 

 

See if your newly acquired cable makes "him" work plugged into a wall outlet, otherwise all this other chat is academic. 



#34 B 26354

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Posted 19 February 2021 - 08:06 PM

No that's perfect. It makes me profoundly less nervous about plugging this beast in, because chasing objects with the fine controls is nowhere near as scary as frying it or myself. But it also tells me enough to understand what particulars you are discussing about the power supplies and why.

PM sent.  grin.gif




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