Has anyone made bartels or Ek's box or similar - Page 10

bojan · #**181** 05-02-2010, 11:35 AM

But you will still need power for encoders

bobson (Bob) · #**182** 05-02-2010, 12:29 PM

Hi Bojan,

Yes, even with bluetooth you will still need power for encoders. But less cables is always good idea and considering most new laptops dont come with serial port.

cheers

mswhin63 (Malcolm) · #**183** 05-02-2010, 12:48 PM

The encoders I am testing are low power - so the spec sheet says.

I am also considering a simple 9V battery supply with a charger too and external power input for longer obs.

The main box is a handheld device with RJ12 an in-built battery compartment so I have decided to go SOIC instead of DIL to reduce size.

bobson (Bob) · #**184** 05-02-2010, 07:25 PM

Sounds very interesting Malcolm. I am sure if you develop something like that many members here would be interested to buy it.

bob

bobson (Bob) · #**185** 06-02-2010, 02:24 PM

Just to let everyone know that USB to Serial adopter from Jaycar works perfectly. It comes with mini CD ROM driver or if you need driver for Vista it can be downloaded from Internet from their website.

Its $24.95 Digitech CAT. NO. XC4834

Ones installed the driver, power up your EK box, open Hyper Terminal, go to new connection and should show which COM port it is on, my was on COM3. Ones I know which port the rest is easy to configure with other software you chose.

bob

scope (Tony) · #**186** 27-04-2010, 07:53 PM

I built a Mel Bartels GOTO drive system (stepper motor not servo motors) and have got it working. The system is relatively easy to build provided you are a bit handy with tools etc. but debugging the software has been difficult.

I am currently working on reducing the drive vibration and still don't have the slewing speeds as fast as I would like them. I suspect I don't have enough grunt in the power transformer to drive both motors at full slewing speed. I will get back to this problem as soon as I finish some of the other projects I have started and have not finished yet.http://www.iceinspace.com.au/forum/....s/thumbsup.gif

Rod · #**187** 28-04-2010, 10:54 AM

Hi Tony,

Good to see another Barteliser on iceinspace! I have relatively fast slews (for a stepper system). Flywheels help a lot - mine are just old bearings fitted to the worm. I also had the overvoltage circuit installed and now run at about 20 volts. I am driving 5.4 volt steppers. Slew speed is about 3.5 degrees per second. I can go a little quicker (4 degrees per second) if everything is really well balanced.

I also found the laptop makes a bit of difference. Some laptops allow more speed than others. The one I use at the moment runs smoother, quieter microsteps when tracking but slews a little slower than others I have used.

Hope to hear more about your project,

Rod.

bojan · #**188** 28-04-2010, 10:57 AM

Hi Tony,
the essential thing is high enough power supply voltage for higher slew rates... 2 or 3x higher than rated for motors are a good start.
Also, the motors must be appropriate. Low voltage/high current ones will spin faster (because of lower coil inductance).
As far as vibration is concerned, this may be the tricky one.
I solved it by using rubber tubes (from fuel supply) as coupling between motor shaft and worm.
Another place where I had a problem was my spider (it was resonating with PWM frequency, together with the fiber-glass tube). I had to pumper it with absorbing material to dampen the vibrations - I was mistaking them for astigmatism in the beginning :-)

scope (Tony) · #**189** 28-04-2010, 07:26 PM

Thanks Bojan and Rod for your comments on my post regarding the Mel Bartels GOTO system. This is the first time I've heard of anyone else working with this system in Aus. The comments seem to be in line with what I had started to understand were the issues with slewing speed in particular. I have previously tried to use 0.9 degree 17V motors for the smaller step size but thought the higher voltage was a barrier to the slewing speeds I was after. I have since changed motors to 1.8 degree 5V motors but have not had a lot of success with these either.
I would be very interested to discuss software settings etc. with anyone who is willing as I have a lot to learn still. I will post some photos once I figure out how to attach them to these posts (just joined).

bojan · #**190** 28-04-2010, 07:46 PM

Quote:

Originally Posted by scope

This is the first time I've heard of anyone else working with this system in Aus.

There are plenty of us here

I have use it for 7-8 years (I think)
Steve (Kinetic) is also one of us, Avandonk another (they are both using Bartels' system on their GEM's.
I too plan to "bartelise" my EQ6 one day ..
You are most welcome, I am sure your system will work like a breeze sooner than later :-)

alistairsam · #**191** 19-06-2010, 09:47 AM

Hi,

thought this program might be useful for people trying to make their own optical encoders for the Bartels system or similar.

has a program that can generate 7 different types of encoder wheels that can be printed out.

http://www.mindspring.com/~tom2000/D...Codewheel.html

bobson (Bob) · #**192** 19-06-2010, 04:44 PM

That looks very interesting. Thanks for sharing.

bob

bojan · #**193** 19-06-2010, 07:04 PM

Very useful, thank you :-)

alistairsam · #**194** 19-06-2010, 08:22 PM

Hi,

Is there any thread dedicated to building optical encoders including the electronics?
what would the minimum number of divisions on the encoder wheel be for the bartels system?
if a simple IR transmitter/receiver pair salvaged from printers, hooked up to schmitt triggers thus generating square waves be sufficient, or would the Ek's box also be required?

bojan · #**195** 19-06-2010, 08:33 PM

You can find this info in this thread...
For Bartels' 5000 ~ 10000 (1200 ~ 2500 lines on wheel if it is directly coupled) ticks per rot of main shafts is good enough.
And yes, I do recommend EK box.
While the serial mouse interface can be used, it seems scope.exe has a problem with interrupt handling (generated by mouse driver) when pushing the scope while in track mode, resulting in missing position update (sometimes.. but once in the evening is once too many) and the scope loses the correct information on position it is pointed at.
EK box keeps this information locally (inside it's own microcontroller) so the information is always correct and can be updated on the demand from scope.exe

alistairsam · #**196** 19-06-2010, 08:55 PM

thanks. Is the 2500 translated to 10000 by gear reduction or by the software?

MrB (Simon) · #**197** 20-06-2010, 03:11 AM

If you mean the 2500 lines on the encoder disk end up being 10000 pulses, Neither.
Well, kinda by the software, it needs to interpret the signals from the two sensors.
It's called quadrature encoding.
Each line has two edges, one leading and one trailing, therefore there are 5000 state changes that one sensor can detect... since these rotary encoders need a second sensor(slightly offset from the first) to detect direction of rotation, it's now possible to detect 10000 state changes.

Tiotion (Jack) · #**198** 19-08-2010, 09:01 PM

Hi all,
Quick question to those who have built David Eks box... how did you make the cables from the encoder to the circuit? Does anybody have a link? Ive seen flat cables and RJ 12 (phone line?) cables but it is still unclear how these are made. I plan on using US digital S6 encoders.

Thanks
Jack

mswhin63 (Malcolm) · #**199** 19-08-2010, 10:26 PM

I used telephone standard and curly cords and reterminated them, although I have a open telephone cablers license so I have the tools. No photos though. I have removed my system for the moment until I finish my mount for the DOB.

I am also going to look at a different encoders compared to the US Digital with the possible cost reduction but it's only an experiment. I already have the encoders but I need to make the shaft.

bojan · #**200** 20-08-2010, 05:30 AM

IDC connectors (2x5) and flat ribbon cables are OK. There is no need for any special tools.. just vice.
See here:
http://www.iceinspace.com.au/forum/a...se.php?a=65266

In case of 2x5 IDC connector, you have to split cable first, if you want only 5 wires, or, you just leave all 10 wires.. One row of connector sockets and 5 wires will be un-used, but this doesn't matter really.