Focus control of a Meade 1209 electric focuser

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lknoll
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Focus control of a Meade 1209 electric focuser

Post by lknoll » Wed Oct 18, 2006 7:26 pm

Hello: I have a Meade 1209 focuser on order and want to control it remotely using some sort of autofocusing sw via MS Remote Terminal. I have two questions ...

1. Do FCUSB and/or FocusPal support the Meade 1209 electric focuser?

2. If FCUSB supports the Meade 1209, what popular (but relatively inexpensive!) software package(s) drives FCUSB via the ASCOM focuser standard?

If all else fails I suppose I can just use a parallel port bit controller like GPINTcheck to control my 1209 (with my own parallel port interface to it), but it sure would be nice to buy something that already works.

Cheers,
- Leonard Knoll
The first step is admitting you are addicted to astronomy.

dpanderson
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Post by dpanderson » Fri Oct 20, 2006 9:14 am

I have not yet had a customer try the FCUSB with a Meade 1209 as far as I know. I did a little Google searching, but could not find enough information where I can conclusively say that it will work. I suspect it does, because it appears that the 1209 uses a DC motor.

Do you already have the 1209? If so, perhaps you can give me the information I am looking for. Does the coiled cable unplug from either the focuer or the hand controller? If so, what type of connector does it use (take a picture and send it to me if you don't know the connector style)?
Doug Anderson
Shoestring Astronomy
http://www.ShoestringAstronomy.com

lknoll
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Controlling Meade 1209 with FocusPal and FCUSB

Post by lknoll » Fri Oct 20, 2006 11:14 am

I haven't got the 1209 yet but when I do (probably in a week or so) I'll let you know what kind of connectors and motor it uses. I'm an electronics technologist so I plan on poking around in it anyway. Another thing I want to do is eliminate the need for batteries in its controller since I'll be using it remotely (hopefully via your sw) with a MS Remote Desktop connection to my outdoor computer from my dining room this winter.

If this works out OK, it could mean a relatively inexpensive remotely controlled electric focuser solution for a lot of folks like me who don't have thousands of dollars kicking around for astrotoys. Hey, it could also mean more sales for you! :)

- Leonard
The first step is admitting you are addicted to astronomy.

dpanderson
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Post by dpanderson » Fri Oct 20, 2006 12:45 pm

That was exactly why I developed the FCUSB. I found myself looking at a picture on a laptop display to evaluate focus, then turning around and trying to find the focuser handcontroller in the dark to adjust focus, repeat, repeat... Now I can run it all from the laptop. I use a JMI Motofocus on my ED-80 and I love it!

I look forward to working with you on this.
Doug Anderson
Shoestring Astronomy
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dpanderson
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Post by dpanderson » Fri Oct 20, 2006 4:25 pm

Oops! To answer your second question:

Shoestring Astronomy provides stand-alone software for free called FocusPal. It can be downloaded from the website, it is free, and it does not require the ASCOM platform.

Any third-party software such as DSLRFocus, MaximDL, and I believe Images Plus that supports ASCOM focusers should work with the FCUSB and its ASCOM driver.
Doug Anderson
Shoestring Astronomy
http://www.ShoestringAstronomy.com

lknoll
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Received Meade 1209 focuser

Post by lknoll » Thu Nov 02, 2006 7:10 pm

It does indeed have the 3.5mm 'stereo plug' (ie: tip, ring, and ground) interface to the hand controller. The hand controller also supplies 12VDC (eight AAA size batteries) to the focuser. I still have to taske it apart to see what's inside the hand controller, but I suspect it is nothing more than polarity reversal switching of the 12VDC through one of the tip or ring contacts.

The hand controller has the following three buttons: "IN", "OUT", and "SPEED". The "SPEED" button is probably nothing more than a contact which supplies a pulse on either the tip or ring (for the duration of the switch closure) to the focuser which tells it to switch to the next speed. Switching of the speeds is cyclic which reinforces my guess about this function.

I'll keep you up to date. I'm very busy right now but I'll probably get around to it this weekend.

- Leonard
The first step is admitting you are addicted to astronomy.

MacDougal
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Post by MacDougal » Sat Nov 04, 2006 12:39 pm

I plan on purchasing a 1209 also. It is about the only thing I can afford looking at all the choices. I could pay more for the focuser than I paid for my scope :-)

I hope someone is sucessful using the Focus Motor Control. I don't know the current draw for the motor. Anyone know if it is less than 100ma?
Also I am guessing the motor is probably 12V since it uses 8 AA batteries.

Please help... Thansk

lknoll
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Meade 1209 focuser on the operating table

Post by lknoll » Sat Nov 04, 2006 4:13 pm

OK, I took apart the hand controller and unfortunately it's not just simple switch closures. There are about 5 small ICs which I will have to identify to reverse the circuit. I've reversed entire amplifiers and ICs under microscopes before so this is not a problem. But before spending time on this, I am first going to see what the signals on the 3.5mm phono plug look like on my oscilloscope. I'll send an update soon (menaing +/- 1 week :).

The buttons on the hand controller are the simple carbon impregnated polymer type which press against exposed HASL contacts on the PCB. I measured the resistance of the carbon impregnated pads and they are ~100ohms, so a simple relay closure or analog switch across these contacts would work just fine.

So the quick and dirty route here would be to have relays or analog switches (controlled by 5V TTL level signals from a parallel port) to simulate the 3 button closures on the hand controller.

- Leonard
The first step is admitting you are addicted to astronomy.

MacDougal
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Post by MacDougal » Sun Nov 05, 2006 9:25 am

I have ordered a Meade 1209 focuser. I did a little research on a LX200 Yahoo Group and found the following. I do not understand how all of this works but I hope this is helpful information to someone who does.

1209 motor control is a two wire circuit. Direction is changed by polarity reversal. Slow speed is at 5V and Fast speed is at 12V. PWM would be better than DC because you can vary the PWM pulses to change the speed. If using DC you may not get variable speed functions.

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Post by dpanderson » Sun Nov 05, 2006 5:25 pm

MacDougal and Leonard

Thank you for this information, this is exactly what I needed to know. Assuming the information you found is correct, the 3.5mm connector of the 1209 should just plug in and work with the FCUSB. The FCUSB uses pulse-width modulation (PWM) that varies the effective DC voltage from 5V all the way down to 0V by using the speed control slider within the FocusPal software.
Doug Anderson
Shoestring Astronomy
http://www.ShoestringAstronomy.com

lknoll
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meade 1209 on the operating table

Post by lknoll » Wed Nov 08, 2006 8:13 pm

Hi Doug:

OK, I had a chance to do a little oscilloscope probing on the 1209 hand controller unit (with the 'in', 'out', and 'speed' buttons).

As I stated before, it has a 3.5mm 'stereo' plug interconnect.

It turns out that the tip of the plug is the control voltage for the motor. It presents the motor with +12VDC for 'out' direction and -12VDC for the 'in' direction. There are 4 speeds. Highest speed is simply 12VDC to the motor (either + or - for out and in respectively). 2nd speed is 66% duty cycle PWM 12Vp waveform. 3rd speed is 50% duty cycle PWM 12Vp waveform. 3rd (lowest) speed is 33% duty cycle PWM 12Vp waveform. On the highest speed (when 12VDC is being presented to the motor) the current is roughly 40mADC.

The ground sleeve on the 3.5mm plug is, of course, the zero volt reference voltage in the hand controller's circuitry, or 'ground'. The 'ring' connection on the 3.5mm 'stereo' plug appears to have no signal on it at any time wrt the ground sleeve. The 'tip' connection of the plug is where it all happens.

It appears as though the circuitry associated with the 'speed' control button in the hand control unit does not communicate at all with the focuser through the 3.5mm plug. It only changes the duty cycle of the 12V going to the focuser via the 'tip' and 'ground' connections of the 3.5mm plug.

Hope this helps ... please let me know.

Cheers,
Leonard
The first step is admitting you are addicted to astronomy.

dpanderson
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Post by dpanderson » Wed Nov 08, 2006 8:35 pm

Leonard,

I appreciate all your work on this. Your information alone would be enough that I would say the FCUSB will work with the Meade 1209. Furthermore, I just received word today from a customer in Italy that has successfully used the FCUSB with his Meade 1209.

The next time I edit the website, I'll add Meade 1209 to the compatibility list.
Doug Anderson
Shoestring Astronomy
http://www.ShoestringAstronomy.com

lknoll
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Control of 1209 focuser

Post by lknoll » Wed Nov 08, 2006 9:24 pm

Doug: Well, it looks like you just gained another FCUSB/FOCUSPAL customer. It will save me a lot of time that I would otherwise have to spend making mods to the 1209.

Thanks,
Leonard
The first step is admitting you are addicted to astronomy.

anmol77
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Re: Focus control of a Meade 1209 electric focuser

Post by anmol77 » Sun May 01, 2016 8:38 pm

If FCUSB supports the Meade 1209, what popular (but relatively inexpensive!) software package(s) drives FCUSB via the ASCOM focuser standard?????

dpanderson
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Re: Focus control of a Meade 1209 electric focuser

Post by dpanderson » Mon May 09, 2016 8:35 pm

The only one I am familiar with is our Focus Pal app at http://store.shoestringastronomy.com/downloads.htm. It is free but it does not use the ASCOM driver.
Doug Anderson
Shoestring Astronomy
http://www.ShoestringAstronomy.com

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