Re: Max Current Draw for GM811G?
Thanks Brian and Michael.
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Jim W
Phoenix, AZ. USA
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Re: Max Current Draw for GM811G?
Hi Jim,
One more critical factor: balance!? and total scope load.??
If in good balance, my mounts take:
0.35 to 0.55 amps per motor to slew at fastest speed.? So to Park (both motors slew at fastest speed) from a distant target, the total current (17V DC power supply) can take 0.7 to 1.1 amp...usually under that.??
If your system is unbalanced, then it's a question of friction...the worm to ring gear is the place that has no roller bearing...all the friction is there.? For that, I recommend the CRC Brake and Caliper Grease.? That gives lowest friction and highest Timken load rating (60 lbs).? This also will lower the motor power needed.
You can reduce the motor current also by changing the digital "max rate" for the motors.? Gemini has a setting for this.? Lower that max rate to lower the motor current max.? It can take longer to complete the GoTo but that's ok.? We are patient in this hobby!
Here are images of my power booster digital monitor system.? You see that the mount was initially unbalanced and it took 0.77 amps during a fast slew.? Then rebalancing that dropped to 0.6 amps.? When the Gemini is parked no motors turning the amps drops to like 0.18.? this is running a big G11T with Titan RA, a C14 Edge HD scope and Gemini-2.? (That secinfmd photo looks like 18.8V but is really 16.8V...due to slow nighttime camera exposure.... really set to 17.0 V.)
Best, Michael
I know the max current depends on voltage (12 vs 15) and overall load on the mount but has anybody measured the current while slewing using a 12 volt supply?? I am trying to determine if the Pegasus Pocket Powerbox can drive my equipment.
GM811G while slewing - ?
Pegasus FocusCube2 - 0.6 amps
ASI2600MC Pro at max TEC - 3 amps
Dew heaters 2 each - 2.5 amps
Pegasus Pocket Powerbox - 0.5 amps
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Jim W
Phoenix, AZ. USA
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Re: Max Current Draw for GM811G?
Hi Jim
it varies depending on the load and balance, but generally I've found 1.5amps max is about right.
I have a powerbox ultimate (didn't know about the micro version) and while I think it would power the mount, I have mine mounted on the OTA, and power everything on top of the telescope. I prefer to keep my Losmandy powered from a? ground source, it's one less cable that may catch
Brian
On Sat, May 15, 2021 at 11:41 AM Jim Waters < jimwaters@...> wrote: I know the max current depends on voltage (12 vs 15) and overall load on the mount but has anybody measured the current while slewing using a 12 volt supply?? I am trying to determine if the Pegasus Pocket Powerbox can drive my equipment.
GM811G while slewing - ?
Pegasus FocusCube2 - 0.6 amps
ASI2600MC Pro at max TEC - 3 amps
Dew heaters 2 each - 2.5 amps
Pegasus Pocket Powerbox - 0.5 amps
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Jim W
Phoenix, AZ. USA
-- Brian?
Brian Valente portfolio
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Max Current Draw for GM811G?
I know the max current depends on voltage (12 vs 15) and overall load on the mount but has anybody measured the current while slewing using a 12 volt supply?? I am trying to determine if the Pegasus Pocket Powerbox can drive my equipment.
GM811G while slewing - ?
Pegasus FocusCube2 - 0.6 amps
ASI2600MC Pro at max TEC - 3 amps
Dew heaters 2 each - 2.5 amps
Pegasus Pocket Powerbox - 0.5 amps
------------------------
Jim W
Phoenix, AZ. USA
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Re: Minimum duration for Pulseguide?
Hi Paul
How will Gemini respond when it gets a pulse duration that is shorter than the minimum movement for a given gear/servo combination? Will it?
a) ignore the pulse?
b) issue a minimum pulse??
Likewise, will all longer pulses be "rounded up" to the shortest combination of steps corresponding to the requested pulse duration or truncated down?
Reading this thread made me go back and look at the guide logs for my GM811 Dec axis and a "quantization" error may explain some behavior. I am seeing.
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Re: Roadside Treasure will be a Counterweight
Soy el tipo de espa?a, yo me hice mi contrapeso con cemento con el nucleo de 10 kg de acero recubierto de caucho, utilize unas mancuernas viejas, me hice un molde, distribu¨ª los pesos y los cemente con fibra de poliuretano, es solido como una roca, para el perno de apriete a la barra utilic¨¦ una rosca la cual corte en dos y estan unidas con un iman de neodimio, asi la parte interior que toca la barra de contrapeso no gira y no crea marcas. ? 
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Re: Roadside Treasure will be a Counterweight
Hahaha that's easy...near the vets memorial......wink wink wink
I threw it away it was rusty......hahaha
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Brendan
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Re: Roadside Treasure will be a Counterweight
Ok, that's fine. Just tell me at which mile post on Highway 101 you dropped yours. I don't want to give away a piece of junk someone else dropped at a different location.?  ??In the meantime, I'll be turning the slab into a work surface for my wife's jewelry making endeavors. It's only fair since she found it. Russ
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Re: Is G11g/T remote observatory ready....Well almost remote
A loaded question, Jim. You may want to decide on what size SCT you want first. From what I have seen from the experience of those with 11" scopes, guiding starts getting tricky if you are doing deep sky imaging. You really need a steady mount for the long focal length and the tinier objects you'll be going after. I've seen some reports that there can be disappointment that the local seeing conditions can work against these large apertures.
Of course there is the temptation to place all your scopes on one mount and have them all ready to go. But you need to consider flexure and that the greater weights will be flexing all the connections and whatever brackets you might select. If you go side by side that might be an option if you pick some good hardware. Over and under puts a lot of stress on the base scope. And with all the counterweights with a multi-setup you need to control a large mass with precision.? ?
With my G11, I use a C925 during winter and spring to capture galaxies, then switch over to a 102mm refractor for the summer with all the large nebula targets. Sometimes I do a side by side with the 102mm and a 60mm on the other side. But I really would not try mounting all these things all at once due to the complexity. If you start having guiding issues, it might be harder to nail down the solution.
If I were to get an 11" SCT, I would get a Titan just for that, to better manage the payload. But I think the Titans are way backordered right now with the high G11 demands at Losmandy.
Hope this helps.
John
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Re: Is G11g/T remote observatory ready....Well almost remote
Appreciate the response.?
Jim
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Re: Is G11g/T remote observatory ready....Well almost remote
Hi Jim
I am sure you wrote me, but i can't for the life of me find that email, so I apologize for the late response
my answers are inline below:
I am building a new observatory. I will have an sct ( 8-11") and a 4.5" refractor to be placed on the mount.? I'll likely reduce the sct's ( .7x) . While I stated in my heading it's remote, I'm likely to be at the site when I use the equipment.? I would prefer to automate a night's imaging sequence. as if I was remote.? I'm guessing the weight of the equipment will be in the range of 40 - 60 lbs.? The questions I have are as follows;
1.? Is the G11 series with Gemini up to the automated task? In your situation, yes. I use my G11 and G11T with unattended operation for days at a time (although in my driveway). the only thing the Gemin lacks is automated homing. if you are there next to it and something happens that requires that, you can reset it to CWD position and you are good to go.
2.? Should I really be looking at the G11T vs. G11G? because of the imaging equipment? I think either mount would be appropriate.?
3.? Does the G11G with the spring-loaded Ra and DEC perform better than the G11T if you stay within its weight limits? Generally the spring loaded worm (SLW) makes life easier because you don't have to think about east biasing your mount
4.? If I purchase the G11G, the RA extension should be included. it's not included, but you can add it. I'd recommend looking at our configurable mounts where you can customize your mount configuration?
5. What else should I be considering? Additional counterweights, certainly :)
I would appreciate any advice from the group.
Thanks,
Jim
-- Brian?
Brian Valente portfolio
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Re: Roadside Treasure will be a Counterweight
Hey that's mine...I dropped it.....! hahahaha
Well maybe not!?? Ummm just some advice.....get it powder coated when done ummm also over drill the shaft and insert a soft brass collar as this will be more easy of the counterweight shaft.?? Like the . I still drool over them.....Homer style.
--
Brendan
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Re: Reducing DEC Backlash with Titan 50
OK, Michael, here are my thoughts:
I suspect I have plenty of grease in there now, and my problem has been properly adjusting the mesh.? I have made a mental note that when I'm ready to re-grease the worms, I'll order the CRC Brake & Caliper grease.? I have a friend who bought the same mount, new, when I did from Losmandy.? He uses the calipers and gave me some measurements that work good for him for gap behind the worm blocks.? I think he said 0.030" for the DEC.? I measured and I think I had to go a little wider than that to eliminate the binding noise.
For DEC backlash.... I'm just going to adjust the mesh so I have no physical play when rotating by hand, and the mount slews smoothly with no stalls, no binding noises.? The block end cap needs to be snugged with no torque (I actually saw a video yesterday that Scott did, saying put no torque on those end caps).? I'll turn off DEC Comp in PHD2, and experiment with some TVC adjustments in Gemini 2 to hold down backlash.
I'll re-grease probably sometime in the next few months.
Thanks so much.
Dan??
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Is G11g/T remote observatory ready....Well almost remote
I am building a new observatory. I will have an sct ( 8-11") and a 4.5" refractor to be placed on the mount.? I'll likely reduce the sct's ( .7x) . While I stated in my heading it's remote, I'm likely to be at the site when I use the equipment.? I would prefer to automate a night's imaging sequence. as if I was remote.? I'm guessing the weight of the equipment will be in the range of 40 - 60 lbs.? The questions I have are as follows;
1.? Is the G11 series with Gemini up to the automated task?
2.? Should I really be looking at the G11T vs. G11G? because of the imaging equipment?
3.? Does the G11G with the spring-loaded Ra and DEC perform better than the G11T if you stay within its weight limits?
4.? If I purchase the G11G, the RA extension should be included.
5. What else should I be considering?
I would appreciate any advice from the group.
Thanks,
Jim
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Re: Roadside Treasure will be a Counterweight
I had a subwoofer speaker blown one day and thought of throwing it out, but then I realized that the magnet is heavy and has a nice-sized hole, so I made a counterweight out of it.?
I bolt it to the shaft instead of the toe guard and with the addition of a #7 Losamdy CW, I am able to balance my 8" RC.
I also use a #4 counterweight from the old CG3 mount in addition to a #22 Losmandy CW for balancing my 10" RC. I also use it as a toe guard.
#22 was not enough to balance this scope.?
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Re: Minimum duration for Pulseguide?
Thank you for the solid response Paul.
I have a GM8 and G11 so the information is valuable.
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Re: Minimum duration for Pulseguide?
The minimum duration will be based on minimum step size of the mount. Step sizes are: 0.375 arcsec/step for Titan,? 0.5625 for G11, and 1.13 for GM8.
If the guiding rate is 0.5x, then the movement for 50ms pulse is 0.375 arcsecs. A Titan can move that much, but for a G11 or GM8 the step is too large. For a G11 at 0.5x rate the minimum pulse will be 75ms and for GM8 - 150ms.
Regards,
? ? -Paul
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On Wed, May 12, 2021 at 04:57 PM, Stephen Migol wrote:
Is there a defined minimum duration for Pulseguide?
Is this limited by:
1. RS232 serial port
2. Ethernet
3. Motor type
4. Gemini 1 vs 2
I'm curious about the reliability of triggering minimum movements of 50 to 80 milliseconds.? I am trying to guide at long focal lengths and need to nudge the mount to control football stars in DEC.
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Re: Minimum duration for Pulseguide?
I'll contact you off list.??
Good to know that there isn't a minimum movement during guiding.
Stephen
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Re: Minimum duration for Pulseguide?
Steve,
Min Duration for Calibration ...that sometimes needs to be like 150 msec to get a good movement, depending on the FL of the scope.? But min for guiding? That can be small...
Overall, I think that your system seems to have a mechanical issue. As you live near me, why not bring your mount head over and I'll see if I can tune it up.? I'm back home....not sure how long.? Give me a call...
Michael Sunnyvale (for now!)
Is there a defined minimum duration for Pulseguide?
Is this limited by:
1. RS232 serial port
2. Ethernet
3. Motor type
4. Gemini 1 vs 2
I'm curious about the reliability of triggering minimum movements of 50 to 80 milliseconds.? I am trying to guide at long focal lengths and need to nudge the mount to control football stars in DEC.
|
Minimum duration for Pulseguide?
Is there a defined minimum duration for Pulseguide?
Is this limited by:
1. RS232 serial port
2. Ethernet
3. Motor type
4. Gemini 1 vs 2
I'm curious about the reliability of triggering minimum movements of 50 to 80 milliseconds.? I am trying to guide at long focal lengths and need to nudge the mount to control football stars in DEC.
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Michael Herman
Davidspain
Russell Milton
Paul Kanevsky