Question 2.
And this is really a question for those using Palm devices.
Where can one buy a reasonably priced serial cable to connect the David Ek box to my Palm Lifedrive?
Is it that simple? Do I need a null modem adapter?
Hi Chris,
This links is about a different planetarium program but might help you:
I've thought about using the Bluetooth facility, but the cost and the complexity are too daunting!
I often use bluetooth and a Pocket PC (running astromist) to control my Bartelised Dob. It was not expensive - the serial bluetooth converter cost about $70 from ebay. I decided on bluetooth because the serial cable for my Pocket PC was $55, so there was very little point keeping the cable. It was not difficult to configure - although I have to admit a friend did the hyperterminal settings for me. It is very convenient. I also use it with a laptop and carte du ciel. I can send coordinates from up to 45 metres away if I need to.
This project is becoming a head ache
I could get only a few parts that are exact match with the ones from David Eks website.
10uF 35V Electrolytic capacitors, neither Dick Smith nor Jaycar have in stock, they say maybe next week. And thats what they told me a few weeks ago and the same today. And its not 35V but 25V which they say should be OK. They promised this time it's definitely ordered and should be in the shop by Thursday.
Also 0.1uF Monolithic capacitor doesn't look like the ones from Dave's supplier but again they say it should be OK.
10K Ohm 0.25 Watt resistors don't exist here in those shops, again neither Dick Smith nor Jaycar, they gave me 0.5 WATT and that should be OK.
Not to mention problem getting encoders, still hunting for them.
Now I understand why people just buy Argo Navis. Yes, it is expensive, but. When you consider that after all I will end up buying encoders from Garry. And then you need laptop to hook everything on, and hope everything works as planed.
I will still try to get encoders from somewhere else first and finish my EK box. Maybe I should have built Bartels system instead
This project is becoming a head ache
I could get only a few parts that are exact match with the ones from David Eks website.
bob
I must confess that I took the easy route when I built mine.
David Ek gives a list of components, all available from Jameco in the USA. http://www.atmsite.org/contrib/Ek/dsc/build.html
One order and all the parts were sitting in front of me within a week or two.
I also got my S2 2048-B encoders from US Digital, as suggested by David. http://www.usdigital.com/
With the AU$ at it's present high against the US$, I would suggest that Jameco and US Digital might be the easiest way to go.
I've decided to try the Bluetooth option, and have an Aircable en route at the moment, to be paired up with a Palm Lifedrive sourced from ebay for $67!
I don't have a great deal of confidence in my abilities to get it all hooked up and going, but I'll never know if I don't have a go!
And I have no doubt that if I have problems somebody here at IIS will have the answer!
Yes, you are right. I had to order bits from Far Circuits. I should have ordered the rest from Jamaco and problem solved. But encoders that you mention from US Digital are quite expensive. I don't know what CPR you have, but I would go with 2500 to make 10 000 (4x). And they are $90 US plus delivery. If you buy them from Garry he sells 10 000 ones with the kit for my scope for $288.10 delivered.
From my experience, every time I try to do something cheaper I end up paying more at the end
I made big mistake when I had chance to get EQ6 GoTo for $1000 a few weeks ago. I thought it would be awkward to use it with my 12" Bintel but then I saw this website with custom made pier:
If you buy them from Garry he sells 10 000 ones with the kit for my scope for $288.10 delivered.
From my experience, every time I try to do something cheaper I end up paying more at the end
You're not alone in spending more when you try to save, I shudder to think how much I've wasted!
My understanding is that Gary sells 2500 CPR encoders that operate in quadrature giving the 10,000 CPR.
Gary advised me at IISAC09 that the US Digital S2 2048-b is effectively the same thing, and would be quite adequate to hook up to an Argo Navis(AN), giving 8192 CPR, and more if gearing was employed.
I decided to try to get the best out of what I already have, before investing in the AN, again trying to save money!
We shall see!
Well I finally got the electronics and most of the hardware completed and tested for my EK box. I am currently ALT 10000CPR and 10000CPR for AZ although the gear has provided 23000CPR for AZ.
It took some time because I wanted to completely re-design the concept and that was to have all the components removable if i decided to sell the scope. Well that part worked well too.
Finally I was able to get accurate readings using a USB to Serial converter as well so I can connect it to my USB port.
I still have more to do as I have designed it to be upgradable without major modifacation to the hardware. My first design was based on a single board but I am now going to work on a Motherboard / Sub-board design so if i wish to upgrade I don't need to change the whole box.
It is nice to get a DIY project to work, and without too much hassle as well.
Well done mate! Could you post some pics.
If you dont mind to tell us where did you get encoders from. Or you can PM me with info.
Also about USB to serial converter, which one do you use?
I completed my EK box a while ago but now need encoders.
This project is becoming a head ache
I could get only a few parts that are exact match with the ones from David Eks website.
10uF 35V Electrolytic capacitors, neither Dick Smith nor Jaycar have in stock, they say maybe next week. And thats what they told me a few weeks ago and the same today. And its not 35V but 25V which they say should be OK. They promised this time it's definitely ordered and should be in the shop by Thursday.
Also 0.1uF Monolithic capacitor doesn't look like the ones from Dave's supplier but again they say it should be OK.
10K Ohm 0.25 Watt resistors don't exist here in those shops, again neither Dick Smith nor Jaycar, they gave me 0.5 WATT and that should be OK.
Not to mention problem getting encoders, still hunting for them.
Now I understand why people just buy Argo Navis. Yes, it is expensive, but. When you consider that after all I will end up buying encoders from Garry. And then you need laptop to hook everything on, and hope everything works as planed.
I will still try to get encoders from somewhere else first and finish my EK box. Maybe I should have built Bartels system instead
cheers
bob
Bob,
there are no critical parts in Ek box.
10k may well be anything between 10k and 33k, or even higher - they are just pull-up resistors..
Caps are also not critical, anything above 10V and more than 10uF will do just fine (they are caps in charge pump of RS232 interface chip - not critical at all).
The only thing which is critical re voltage are caps around voltage regulator (C2) because there you will have supply voltage (12-15V ) so it should be rated 20-25V, just in case.
I have gone away from the traditional use of encoders. I have pictures of my encoder arrangement very simple concept and instead of using a fixed encoder for ALT I am using an Inclonometer instead specs here.
This avoids drilling any holes at all. As shown in my picture, I use 3M pull off double sided sticky for just about everything. The stuff i use it oversecure and as i have done on numerous occasion while experiemtenting was to remove and replace with soooooo much ease.
It is a bit harder on the AZ encoder but for the that I have done the same although I will be machining simple special adaption to allow temporary and accurate fitting as well as removal of encoders.
The electronics, I am redesigning sorry no pictures. I also hope to manfacturer a number of these to give a lower cost alternative in different stage in partial DIY to full production.
Before I do that I need to make sure that I cover all step to ensure the consumer is getting the best solution as well as easy to fit.
The USB to Serial convertor is crap but effective, The problem is these annoying blue lights that flash during communications EUGH.
I hope to make 3 designs, first is the pure serial, the USB and finally Bluetooth. All of these are highly acheivable in my design as a complete unit and not put together in a mess.
I am limited by funds a bit at the moment, my wife on a disability support pension is unable to assist and Centrelink require my buisness to run at either no profit or a loss until she is off the pension. A lot harder than you think.
Overall I think it can be a lovely Push to Project, I have tested it with CDC and Worldwide Telescope along with Scope.exe
No worries mate, I got that important parts you mentioned from FarCircuit and the rest from Jaycar, board and chip from Simon. EK box is already finished. Shopping for encoders now
BTW, What do you think about this encoders from Ebay that Martin posted: http://cgi.ebay.com.au/Oak-Grigsby-R...item5acfd0836c
Brand new rotary encoder
Manufacturer: Oak / Grigsby
Model: 91Q128-43-00110
128 pulses per revolution
2 channel full quadrature encoding
1" square body with a sealed enclosure
1/4" diameter shaft, .4" long
4" cable terminated with a 4 pin female plug
Martin,
I know about those ones on Ebay, although the first link you posted is very tempting. It would be very cheap and a lot of gear ratio to gain at least 4-5 000 ticks per rev.
Malcolm,
Thats very interesting design mate. Keep us posted.
The Ebay link didn't work for me, but the specs are a bit low for accurate my purposes, but may be OK for general viewing purposes. Generally for good accuracy 5000 Quadriture counts per revolution is more common. But the resolution can be whatever you want.
The main advantage of the inclonometer in the US Digital link is that it is a completey self contain unit that requires no drilling of the holes at all in the OTA or DOB base. A quick easy option, although the delivery price for a single unit is quite high.
If I do make the boards for the electronics I may (more than likely) consider bringing in the Encoders in bulk as well, this may take a bit of time though, how long I do not know.
With many people using computers and Rubylith screening used on site the PC is becoming a better alternative. I will also be testing Astronomist for PDA Win and PALM later.
With CDC program the tracking was brilliant, I could see the cursor following my scope with so much ease. Worldwide Telescope didn't track so well, I had to keep clicking the Centre button to find out where my scope was positioned. Still very early days yet, with more time I sure I can finish it off quickly.
No worries mate, I got that important parts you mentioned from FarCircuit and the rest from Jaycar, board and chip from Simon. EK box is already finished. Shopping for encoders now
BTW, What do you think about this encoders from Ebay that Martin posted: http://cgi.ebay.com.au/Oak-Grigsby-R...item5acfd0836c
Brand new rotary encoder
Manufacturer: Oak / Grigsby
Model: 91Q128-43-00110
128 pulses per revolution
2 channel full quadrature encoding
1" square body with a sealed enclosure
1/4" diameter shaft, .4" long
4" cable terminated with a 4 pin female plug
This link did not work either today (try this one directly copied from Martin's post: http://cgi.ebay.com.au/Oak-Grigsby-R...item5acfd0836c).
It seems it is not optical (has mechanical contacts - brushes), which is not bad as such. Maybe not as reliable as optical, but then, the application on telescope (which moves slowly compared to some other machinery) is not mechanically demanding.
Wether it is good (in terms of resolution) that depends, you will need additional gearbox or pulley-belt system to obtain required number of tics/rev of the mount shafts.
However, for Bartel's, resolution is 5000 ~ 10000 is quite enough. So you only need 10 ~ 20x (I have ~20, 6mm roller on 120mm wheel, friction).
I am planning to use timing belts and pulleys in the near future (from old printers... ).
Malcolm, how did you connect your inclinometer to PC? I am not sure it has quad outputs...
Malcolm, how did you connect your inclinometer to PC? I am not sure it has quad outputs...
The inclinometer connects to the EK box, then the EK conects to the PC. The Incl is a 10,000 step encoder fitted to a weight and damper to stop vibration and alway points verticle. This is why the inclinometer cannot be used for AZ application .
The EK, although not fully tested I believe can work up to 65,000 steps but can believe that would need that much for a push to. The EK I currently use with ASCOM drivers to various applications.
I must admit the 5V regulator TO220 get quite warm so I believe there is little or no buffering on the PIC, instead communicates with the PC most or all the time.
This link did not work either today (try this one directly copied from Martin's post: http://cgi.ebay.com.au/Oak-Grigsby-R...item5acfd0836c).
It seems it is not optical (has mechanical contacts - brushes), which is not bad as such. Maybe not as reliable as optical, but then, the application on telescope (which moves slowly compared to some other machinery) is not mechanically demanding.
Wether it is good (in terms of resolution) that depends, you will need additional gearbox or pulley-belt system to obtain required number of tics/rev of the mount shafts.
I use the scope only for visual, so I think with gear ratio 40:1 or even 50:1 I should be ok.
This encoders would cost me only around $40 dollars delivered.
Let me know if you can if they are electrically suitable for this purpose.
I use the scope only for visual, so I think with gear ratio 40:1 or even 50:1 I should be ok.
This encoders would cost me only around $40 dollars delivered.
Let me know if you can if they are electrically suitable for this purpose.
Thanks mate
cheers
Yes, they should be OK.
It is not clear from picture how to connect them, though.
If it is mechanical (easily checked with ohm-meter, contacts will be open or closed, depending on position), you will have two wires for CHA, other two for CHB.
One of each goes to GND, other two go to Ek box inputs (CHA, CHB). You will not need to connect +5V.
If it is optical, it will require +5V, and you will have to determine where + is (if they do not send you data sheet - I tried to find it on web, but no luck..)
If they are mechanical, it may require extra circuitry to get the pulses needed for EK box whereas the optical encoders provide the necessary pulses out from the encoder. I have never thought about the differences between mechanical or optical.
I believe the "+" and "-" indicate the phase of the output where the other pin could be the common but is a bit confusing without the connection diagram. Nothing on the manufacturers website either.
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