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Where to find a Dec Cord for AccuTrack 4000 Dual Axis Controller

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#26 PaulEK

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Posted 05 November 2018 - 04:47 PM

Here are the guts of the AT 4000.

 

A-T 2.jpg



#27 PaulEK

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Posted 05 November 2018 - 04:56 PM

And, finally, I have both the general instruction manual for the AccuTrack series of controllers, and the specific manual for the AccuTrack 4000. I'll include these when I sell this scope/mount kit, but wanted to have the manuals for reference, just in case I come upon one again. I looked for more info online about these but found very little. If anyone would like some JPEGs of either or both manuals, please PM me.

 

I hooked everything up a little while ago, and it works just fine!

 

A-T 3.jpg

 

(Yes, my shop in the background is quite a mess. It's usually not so bad, but we had a fire in the fire ring in our driveway a while back and have not put things back as they should be yet!)



#28 DAVIDG

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Posted 05 November 2018 - 05:15 PM

 So you just paralleled  the wiring from the original 6 pin plug to the two conductor phono plug ? What is amazing is that all those logic ICs can be easily replaced today with a  microcontroller and about 50 lines of code.

 

               - Dave 



#29 PaulEK

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Posted 05 November 2018 - 05:28 PM

Dave: Yes, I just used a multi-meter to figure out which pins supplied the 12vdc power and my son (who is much better at reaching into tight places with his soldering iron) soldered in the phones plug.

 

And he agrees with you about the complexity of the innards of this machine! Still, it's working fine after decades, so no complaints form me.


Edited by PaulEK, 05 November 2018 - 05:29 PM.


#30 DAVIDG

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Posted 06 November 2018 - 09:45 AM

 Glad to hear that it works. How that thing works is all those IC's are taking the  frequency of the crystal which is most likely 1 Mega Hertz and divided it down to between 58 to 62Hz. The switches on the front  set the divisor. So when you divide down a big number you have a bunch a decimal places and you can chance the frequency by a very small and very precise amount.  So you can set  for example Sidereal rate at 60.1250000 Hz.

 

               - Dave 



#31 PaulEK

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Posted 06 November 2018 - 01:14 PM

Yup; 10,000 different settings. The manual includes a graph showing settings for different levels in the sky in order to counter atmospheric refraction. And it actually allows adjustment between 90 and 45 Hz. What the manual does not include (it seems to be missing at least one page) is rate settings for the lunar and solar rates. For a perfect 60 Hz, the setting should be 5000.



#32 DAVIDG

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Posted 06 November 2018 - 01:31 PM

 The circuit is based on the West Bradford drive corrector that was in the August 1975 Sky and Tel https://archive.org/...08-cbr/page/n55

  I'm sure that the manual tells you the chart is for the King rate which is also discussed in the article. Now a day your GOTO telescope  knows the DEC of the object your observing and automatically adjust the drive rate to compensate for atmospheric dispersion like the what the King rate is doing.

 If 60.000 Hz has a  setting 5000 then Lunar rate which is 57.968 Hz should be 4831  and Sidereal which is 60.164 Hz should have a setting of 5014.  These are all based on the  fact that the drive in the scope is geared to track at solar rate at 60.000 Hz which is the majority of  most vintage telescope, like Meade, Cave, Criterion, Edmund, Jaegers, etc.  

 

                - Dave  


Edited by DAVIDG, 06 November 2018 - 01:50 PM.


#33 Jeff B1

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Posted 06 November 2018 - 04:15 PM

 The circuit is based on the West Bradford drive corrector that was in the August 1975 Sky and Tel https://archive.org/...08-cbr/page/n55

  I'm sure that the manual tells you the chart is for the King rate which is also discussed in the article. Now a day your GOTO telescope  knows the DEC of the object your observing and automatically adjust the drive rate to compensate for atmospheric dispersion like the what the King rate is doing.

 If 60.000 Hz has a  setting 5000 then Lunar rate which is 57.968 Hz should be 4831  and Sidereal which is 60.164 Hz should have a setting of 5014.  These are all based on the  fact that the drive in the scope is geared to track at solar rate at 60.000 Hz which is the majority of  most vintage telescope, like Meade, Cave, Criterion, Edmund, Jaegers, etc.  

 

                - Dave  

In the late 1960’s I designed a crystal controlled motor speed control for a project for my work at Link Aviation (flight simulator manufacturer).  It replaced a magnetic drum speed controller in our GP-4B main frame computers.  Long technical story, but it managed to run the heavy drum at exactly 60-RPM.  I published an article in IEEE Journal and something else, long forgotten, with that design and years later someone hijacked my design (wonder who).  They never found out just how lucky they were because Singer-Link could have sued their pants off.

 

Later on I adapted this design as telescope dive corrector (that is no longer working).  Spiders and other critters got in it and, well, you know what happened. So I replaced it with the AccuTrack-4402.  A simple hand paddle has one toggle control for RA and switched DC outputs that operate relays for the AC declination motor. This drive corrector has all the power needed to drive both the 12.5" and 16" telescopes.  Would have loved to have a 4000, but my telescopes are stored away now.

 

Yeah, you say “that’s what they all say.”  Well, the thrill of suing someone was heavy on my nimble mind.  Some other telescope bunch did see the inside of a court house when they took my idea of putting a small drive corrector inside my Dynamics 8 gear housing.  Just got tired of carrying all that stuff so there was ample room inside the case and a “friend” gave the idea to “someone.”


Edited by Jeff B1, 06 November 2018 - 04:21 PM.


#34 PaulEK

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Posted 06 November 2018 - 07:43 PM

 The circuit is based on the West Bradford drive correctowr that was in the August 1975 Sky and Tel https://archive.org/...08-cbr/page/n55

  I'm sure that the manual tells you the chart is for the King rate which is also discussed in the article. Now a day your GOTO telescope  knows the DEC of the object your observing and automatically adjust the drive rate to compensate for atmospheric dispersion like the what the King rate is doing.

 If 60.000 Hz has a  setting 5000 then Lunar rate which is 57.968 Hz should be 4831  and Sidereal which is 60.164 Hz should have a setting of 5014.  These are all based on the  fact that the drive in the scope is geared to track at solar rate at 60.000 Hz which is the majority of  most vintage telescope, like Meade, Cave, Criterion, Edmund, Jaegers, etc.  

 

                - Dave  

I'm curious to know why they used the solar rate as their geared rate, rather than sidereal. The manual does agree with you, though, saying: 'Many telescopes have drive motor and gear systems which drive the telescope at the solar rather than the sidereal rate (when connected to the nominal design frequency AC).'

 

And, can you explain how you came up with the two numbers for lunar and sidereal rates? Are you simply aware of the quantataive difference between the different rates and translated those differences to the Hz and the ratio when related to 5000, or am I missing some math skills?

 

EDIT: I guess I should have checked the link first! Now I get the answers to my questions.


Edited by PaulEK, 06 November 2018 - 07:46 PM.


#35 DAVIDG

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Posted 06 November 2018 - 09:05 PM

 Solar rate is standard clock rate ie one rev in 24.00 hrs ie in rev in 1440 minutes. Sidereal rate is one rev in 1436 minutes so only 4 minutes per day difference. So when observing visually you would only see a slight drift in the position of the objects over a few hours. Also it is easy to make a drive that rotates in one rev in 1440 minutes ie a gear with 144 teeth  and 1/10 rpm motor or 96 tooth gear and 1/15 rpm motor. Sidereal rate requires non standards gears. So the easiest thing to do is make the gearing and motor for solar using a motor that runs at 60.00 Hz and then use  electronics to chances the frequency to drive the scope at sidereal or other rates.

   As for the setting values I took 5000/ 60 and multiplied that by  the frequency given in Sky and Tel article. That could be wrong though because the value on the thumb wheel switches set the value that the crystal frequency is divided by. So for example Lunar rate is 57.968s Hz so the value on switches may need to be larger then 5000 to make the frequency slower then 60hz.  A few minutes with an oscilloscope or a frequency meter with tell you which way the frequency is changing with the values on the switches. If you don't have either of those you can plug an analog clock with a second hand into the corrector and watch how fast the second hand turns when you change the values on the switches .

 

             - Dave 



#36 PaulEK

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Posted 07 November 2018 - 03:43 AM

As soon as I followed your link to the S&T article and was reminded that the solar rate is 1440 minutes, the other things made sense.

 

I plan to sell the whole kit (scope, mount, corrector, etc) so the buyer can choose whether to do the things you described. But it's very interesting, and if I were keeping it, I'd sure play around with this thing, even though I have much newer and easier mounts with drives that I can use for astrophotography. For visual use, I wouldn't care to be so precise, and would just use the joystick to make occasional adjustments.

 

But thanks for all the help! I'll make sure to give the buyer a link to this thread, and it might help others who, like me, wanted to understand these correctors.



#37 Jeff B1

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Posted 08 November 2018 - 02:29 PM

Oh, I always had good service and parts from Jameco Electronics, especially old stuff like your connector:   https://www.jameco.c...catalogId=10001

 

Sorry about going off on a tangent; even now it irritates me how people used to steal stuff from others. Too bad AccuTracks are no longer made.  Good units; mine still works great.


Edited by Jeff B1, 08 November 2018 - 02:36 PM.


#38 PaulEK

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Posted 08 November 2018 - 11:39 PM

No worries! As an author of a book that's had more than 100x illegal e-copies than legal ones uploaded online, I know how it is to have stuff stolen. If I had sold as many hard-copies, I could have retired by now. grin.gif, or should I have put frown.gif?

 

And yes, this does seem like a very well-made unit.


Edited by PaulEK, 08 November 2018 - 11:51 PM.

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#39 Jeff B1

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Posted 09 November 2018 - 06:42 AM

No worries! As an author of a book that's had more than 100x illegal e-copies than legal ones uploaded online, I know how it is to have stuff stolen. If I had sold as many hard-copies, I could have retired by now. grin.gif, or should I have put frown.gif?

 

And yes, this does seem like a very well-made unit.

It was well known then, probably worse now, engineers are some of the worst thieves; once you publish then it was out there for the taking.  I was a young and foolish engineer.  People hate engineers, for some reason, maybe it because we drink a lot flowerred.gif

 

Some of my ALPO Mars reports have been plagiarized in S&T, maybe Astronomy, in the past so I fixed that by inserting gross errors that stand out like a sore thumb.  The perp had no clue.  The lifted drive corrector design even used the same chips!  The last one I made smoked, so it was back to the analog gadgets.  That's okay after redesigning it with CMOS it worked 100% better.  Hum, it has not smoked as of yet. laugh.gif

 

Did you find the parts you needed?


Edited by Jeff B1, 09 November 2018 - 08:18 AM.


#40 PaulEK

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Posted 09 November 2018 - 02:03 PM

Hi Jeff,

 

Yes, it's working just fine now.




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