Polarotor Servo Controller Design

[Achebee]

Plenty of Interest in my area

Sadoun, I could sell 50 of these for you here in Honduras and maybe more..
I would think that adding a servo control to your GBOX would be a no-brainer...After all most serious C_Banders are using servo's, especially in the foreign markets.
Adding a servo controller would make your GBOX a complete set-up, and you would have the corner on the market...
As it stands , as good as GBOX is and handy, and well designed, it is not a complete unit... it is missing a servo control, and therefore is not the beauty that many propose it is..
You have guys like me rigging Pansat 3500's in line, or using the 920's and 922,s and all sorts of outmoded equipment to run servo on Sats that are not for 4DTV..I support and subscribe to 4DTV but that's not the point... Here in this part of the world and other locations many people rely on CBand, and always have and always will.....
The GBOX is a great unit, no doubt... but it is incomplete without a servo controller.
Keep up the good work as always Sadoun, thanks, HB

budfoot, nice design and work.

You can start a new thread about adding polarotor controls to the GBox. Do a survey. If there is enough responds and interest, we might pursue it.

 

[putney]

I was just trying to figure out how to do this with my two servo lnbs. Thanks for bringing the topic back to the surface.

 

[equant]

Time for me to chime in to several of the posts all at once without quoting anything; let's see how I can do...

Budfoot's design is very nice, and a commercial design would certainly want to follow his circuit more than mine. I'm not sure if he's releasing the hardware GPL or not, but... If someone wanted to make a commercial version, they could easily convert the Arduino code to AVR code and run it all off of an AVR. Most likely the cheapest and smallest one available since it doesn't need much I/O nor use fancy uC features like A/D or what-not.. It would take the right person with the right tools very very little time, and the end components should be less than $7.

As far as outside vs inside operation: For those interested in hombrewing... Budfoot's is for indoor use (external power), and mine was for outdoor use (powered from coax). I put the larger power type LM7805 on my Freeduino board, and it ran hot. Budfoot uses an extra 7805 circuit to power the servo, this is a good idea if you're not lazy. I didn't have room for a heat sink, and ran the controller outside in Arizona; I think April through May, so several over 90F days. It ran fine, but I can't guarantee it would have lasted forever. Since then I've gotten dual-output CBand LNBFs, so I haven't used it in a while.

Budfoot doesn't have the inductor in his schematic. Perhaps he can tell us what he used. He mentioned it to me, and it's better than what I used. In my defense, I was just prototyping with what I had on hand. It goes to show though that there's not a lot that's critical about the circuit.

If any of this does inspire a gbox with polarity control, I think Budfoot and I should be first in line for beta-testing.

 

[budfoot]

<snip>

Budfoot doesn't have the inductor in his schematic. Perhaps he can tell us what he used.

If any of this does inspire a gbox with polarity control, I think Budfoot and I should be first in line for beta-testing.

Sorry about that. I'm working on a second page of the schematic with the external components. The inductor is mounted right on the buss between the two F connectors. I used a 1000uH inductor at least in part because I have a bag full of them left over from another project. Up to a point, the more the merrier on the inductance, since we are interested only in the DC on the line. As far as powering the box and the servo from the LNB power, I am a bit skeptical about the advisability of that. Maybe someone could chime in with the specs on a typical LNB power circuit as far as total acceptable current draw, but I suspect that driving the servo from the 14/18 will put an unacceptable load on LNB power.

FWIW I definitely add my 2nd to putting servo control in the GBox. That's really the right place for it. Eliminating connectors from the L band RF path is always a good thing.

 

[crackt]

its good there is some discussion on this subject again. ive had a prototype in my head for awhile with a slightly different twist than just 14/18v polarity control (potential to handle off skew birds). when i have a need for it, ill invest the time to whip something up. at present i dont use servo controlled feedhorns but i have an interest in the wideband corotor.

as for the gbox 4k... im not sure this is the right path to take. in my opinion youd sell more units with a modular approach. i already bought a gbox 3k. why would i want to buy a 4k and end up with a spare positioner. a modular approach to a stand alone unit would make much more sense. for one, all the people who presently own vboxs, gboxs, and other positioners would not need a new positioner. secondly itd also make the use of a corotor on a minibud possible with an hh motor(where the positioner portion would be useless).

my 2 cents. thanks for the documented approach guys.

crackt out,.

 

[Anole]

brainstorming:

I thought I commented before, but let me suggest this again:
Integrating the servo control with a dish-mover, means you could remember the servo position for -each- motor location!

At setup, you dial-in the nominal servo position for say your True South bird.
Then, all other birds inherit this position, unless you adjust them differently.
When you are on any bird and adjust the skew, it is permanently remembered.


As for inside vs outside, I assumed most who had servo-feedhorns, also had wires going out to 'em.
So, the inside version (inside the Vbox 4000) made sense to me.

If I were designing an outside module, taking power off the LNB, I would:
- measure power required by the board
- measure power required to run the servo
- if it seemed there was too much current draw, I'd use a high-efficiency switching regulator to cut the 13/18 volts down to 5v.
This would require shielding and bypassing, but nothing special.
A switcher with 80 or 90% efficiency would use -less- current from the LNB line, and produce far less heat than a normal 7805 regulator.


Other ideas welcome.

 

[crackt]

I thought I commented before, but let me suggest this again:
Integrating the servo control with a dish-mover, means you could remember the servo position for -each- motor location!

At setup, you dial-in the nominal servo position for say your True South bird.
Then, all other birds inherit this position, unless you adjust them differently.
When you are on any bird and adjust the skew, it is permanently remembered.

precisely my thoughts. but this can be accomplished stand alone as well. and this would accomodate a corotor wideband that needs 4 skew positions. at least this is the direction i was heading. storing skew positions for each satellite location via diseqc. the disecq protocol does include provisions for a skew controller but i doubt they are implemented in any way shape or form in the firmware of any reciever.

truthfully what is needed is a modular design. this is also prototyped in my head. this way we would only need one remote and the particular controllers we need for each unique users setup. scalability and backwards compatibility.

crackt out,.

 

[budfoot]

New schematic for my little box up at Budfoot Files. This one includes the external components mounted on the box.

 

[equant]

Making a version of this that does DiceQC shouldn't be that hard (holds breath) and it could do what Anole wants *and* be modular. I drew out a circuit to get the 22kHz signal to the arduino, but I think it's long gone (like my current measurements, of which I did, but I don't remember the outcome other than: it wasn't bad enough to dissuade me).

 

[equant]

New schematic for my little box up at Budfoot Files. This one includes the external components mounted on the box.

Cool, looks good.

Any chance you can post a larger version of the picture that's sort of in the center of the collage/mosaic image? The picture of the inside view of the F / power / xlr connectors?

What are you using for bus wire on the perfboard? And is that wirewrap wire on the top-side?

Also, I linked to your page from mine.

Thanks

 

[crackt]

Making a version of this that does DiceQC shouldn't be that hard (holds breath) and it could do what Anole wants *and* be modular. I drew out a circuit to get the 22kHz signal to the arduino, but I think it's long gone (like my current measurements, of which I did, but I don't remember the outcome other than: it wasn't bad enough to dissuade me).

using diseqc to store the skew for each position is the direction i was going to take. initially i wanted to build a skew controlled to use with the wideband cotor and simply sensing the coax voltage could only provide 2 states. also using diseqc would allow the nominal skew settings to be saved for each orbital position. with diseqc the controller could also reside anywhere on the coax and the servo would only react when the proper position was called. it seemed at the time like the proper path to pursue. i havent bought a corotor yet(bought a orth instead) but i am still interested in that solution if my siamese scalar fails to perform or i need to set up another BUD.

there is definately enuff brain power on this forum to make something very useable.

crackt out,.

 

[budfoot]

Cool, looks good.

Any chance you can post a larger version of the picture that's sort of in the center of the collage/mosaic image? The picture of the inside view of the F / power / xlr connectors?

What are you using for bus wire on the perfboard? And is that wirewrap wire on the top-side?

Also, I linked to your page from mine.

Thanks

I'll add that picture. The buss wire on the perfboard is Belden 20awg tinned copper buss wire and the other hookup wire is indeed 30awg kynar wire wrap wire. I've always liked doing point-to-point with it because it's easy to handle and, oh yeah, I have a ton of it left over from the olden days of wire wrap.

I'll add a sort of "I know better, but it was already that way" about the XLR connector. My whole setup is wired with 1 hot, 2 gnd, 3 pulse, which, to XLR purists is a total atrocity. It should, of course, be 3 hot, 2 pulse, 1 gnd for the purists and the audio fanatics would argue that I shouldn't have used an XLR 3 at all for this purpose. My only excuse for both is that, at least if you accidentally hook it to an audio circuit, the 5V is going to the ground pin.

On another note: I checked the Chaparral specs on the servo motor and they spec the 5V at 500ma, which is way too much to suck out of the LNB power department. I don't seem to have the Monterey schematic for the tuner, so I don't know how much of a load they can handle, but at least one LNB power injector specs 600ma max, so pulling 500ma for the servo would definitely put a strain on that sucker.

 

[ynnedibanez]

this would be the final straw to make me buy a gbox and sell my vbox on ebay!

even though i haven't gotten to set up a c-band dish yet because my landlord wouldn't go for it.
i can't hardly wait to move!!!!!!!!!!!!!!!!!!!!

 

[madbull]

Great stuff you folks got in this tread. I can do the wiring no problem, as I used to wire my on transmitters etc as an old amateur radio op (N4HD). but i am about a complete idiot about the chip programing. I saw your code but how do you get it into the micro processor,(be gentle hehe). I would really like to get one of these up and going, any help appreciated.

 

[equant]

Great stuff you folks got in this tread. I can do the wiring no problem, as I used to wire my on transmitters etc as an old amateur radio op (N4HD). but i am about a complete idiot about the chip programing. I saw your code but how do you get it into the micro processor,(be gentle hehe). I would really like to get one of these up and going, any help appreciated.

There's more than one way to do it, but here are the steps I would take if I was new at this...

(1) Buy an Arduino... I'd get either the RBBB or the BBB from Welcome | Modern Device. RBBB and BBB are two different versions of the Arduino; either will work well. ModernDevice is a great company. You can get pre-built versions of their versions of the Arduino if you're not comfortable soldering all the bits on the board, or are in a hurry, or lazy, or whatever.

(2) Now you need a cable to connect the Arduino to your computer in order to put the code into the Arduino. If you're ordering from ModernDevices, you can get their USB-BUB board... USB BUB Board | Modern Device You can use any FTDI cable though, and maybe you have one, or can find one cheap somewhere else. FTDI cables plug into your computer's USB port, and basically turn it into a serial port. FTDI is supported by Linux, OSX, BSD, windows.

(3) Now go to Arduino - HomePage and download the Arduino IDE. Maybe read some of the "Getting Started" section...

Arduino - MacOSX
Arduino - Windows

... that link gives very clear instructions on how to, well, get started, including connecting the Arduino and uploading code to it. They show you how to test the arduino by making an LED blink. I do this with every Arduino I build. The steps are very easy to follow, and there's a large community of people (IRC and Forums) willing to help, and be nice about it.

(4) Once you've got the LED blinking, you should have no trouble ULing the code for the servo controller, but if you need specific help, come back here. Of course, you have to build the circuit too.

Hope that gets you started.

PS, my semester just ended today, and on my summer to-do list is more servor/motor control projects. Here's hoping I get around to it.

Nathan

 

[madbull]

There's more than one way to do it, but here are the steps I would take if I was new at this...

(1) Buy an Arduino... I'd get either the RBBB or the BBB from Welcome | Modern Device. RBBB and BBB are two different versions of the Arduino; either will work well. ModernDevice is a great company. You can get pre-built versions of their versions of the Arduino if you're not comfortable soldering all the bits on the board, or are in a hurry, or lazy, or whatever.

(2) Now you need a cable to connect the Arduino to your computer in order to put the code into the Arduino. If you're ordering from ModernDevices, you can get their USB-BUB board... USB BUB Board | Modern Device You can use any FTDI cable though, and maybe you have one, or can find one cheap somewhere else. FTDI cables plug into your computer's USB port, and basically turn it into a serial port. FTDI is supported by Linux, OSX, BSD, windows.


(3) Now go to Arduino - HomePage and download the Arduino IDE. Maybe read some of the "Getting Started" section...

Arduino - MacOSX
Arduino - Windows

... that link gives very clear instructions on how to, well, get started, including connecting the Arduino and uploading code to it. They show you how to test the arduino by making an LED blink. I do this with every Arduino I build. The steps are very easy to follow, and there's a large community of people (IRC and Forums) willing to help, and be nice about it.

(4) Once you've got the LED blinking, you should have no trouble ULing the code for the servo controller, but if you need specific help, come back here. Of course, you have to build the circuit too.

Hope that gets you started.

PS, my semester just ended today, and on my summer to-do list is more servor/motor control projects. Here's hoping I get around to it.

Nathan

Thanks a bunch Nathan for taking the time to give me some help , hope you have a great out of school holiday. Think I will order the prewired version of the chip board. then go from there. Should have enough parts laying around here, with maybe the exception of the rf choke to get the project off the ground. I would sure buy one of these suckers if they were available off the shelf.
I may have to get more spoon feeding on the programing. I will get the device and cord you mentioned, then we will see.

Jay