Dave Ek's DSCs

[Howzat]

Being a bit of a DIYer I've started building Steve Ek's DSCs (http://home.earthlink.net/~david.ek/digicircles/)
So far I've completed etching the PCB (see pic) and I've managed to get all the parts needed from Jaycar (http://www.jaycar.com.au) and Dick Smiths (http://www.dse.com.au) except for the crystal clock oscillator which i've ordered from Mouser Electronics (http://www.mouser.com/)
Luckily I have a PIC programmer that i built from a kit a couple of years ago so I can program the EEPROM myself.
I'm probably going to control it using my Zire 71 with PalmDSC (http://palmdsc.dougbraun.com/). The serial cable for the Palm is probably the most expensive part (if you don't count the usb - serial adapter for my laptop) other than the US Digital S2 Optical Encoders I've ordered from BATSC (http://www.batsc.com.au/)
Tomorrow I'll start to solder the components to the PCB and try to find a box to hold it all in.

[Starkler]

Been there, done that except I bought the pcb and the pic pre-programmed.

See my sig :)

[gbeal]

Me too, and it is a very good unit. I use mine with the Palm, and also via a dongle to the PC.
Rob Beck is full of info if you need it, and suggest you PM him if you get stuck. (sorry Robby).

[iceman]

Well done Howzat.. the DSC's are the best upgrade you'll do to your dob!

Good luck with it, can't wait to see it hooked up!

[Astroman]

I also have the EK DSC, but no encoders yet so havent connected it to the scope. I also have another circuit built by my dad which uses stepper motors for encoders, not accurate but it shows how it can be done.

[ving]

now if only i had half a clue when it comes to electronics....

let us know how it goes :)

[Thiink]

What sort of cost are you looking at for getting one of those built including the encoders?

[Howzat]

I already had the palm and a PIC programmer so....
2 X encoders @ $75 ea
1 X PIC16f84 @ $10
1 X case @ $12
1 X PCB etching kit @ $22
1 X Press & Peel Blue @ $35
misc other electronic components $15
1 X palm serial/usb cable @ $36
I also have a telephone cable lying around which I'll use to connect the encoders.
The only other expense will be mounting kit for the encoders. I still haven't decided wheather to build or buy yet

$280 so far, keeping in mind the etching kit, press & peel and serial cable will be used for other things

[Howzat]

Here's the completed circuit board with all components. All I have to do is mount it in a case and mount the encoders and it should be good to go :)

[iceman]

Have you done the spark test? :)

[Starkler]

Ive since heard that the oscillator module is an unneccessary expense, and can be replaced with a cheap 4mhz crystal and two ceramic caps. Mine cost me $20, $10 of that shipping from Farnells .

Sorry that doesnt help you Phil :P

[Starkler]

Quick test.

Plug it into your pc running hyperterminal at 9600 baud and upon power up you should see "v2.0" on the screen.

[Howzat]

Yeah I read that but the osillator only cost me US$1.58 ea (I ordered 5) and US$12 postage




I wasted half a day testing it with hyperterminal, pressing Q to try and get +000 +000 until I read that the Version 2 firmware showed V2.00 at power on and reset :doh:



Luckily no smoke came out as its a bugger to get it all back in :D

[Astroman]

I used the X-tal and two 15pF Caps on mine, works well. Need to get a couple of encoders for mine.

[Vermin]

I've been thinking of upgrading to the 10K step encoders for my Argo Navis. Which means I would have a couple of 8192 step encoders for sale. They are brand new (never used, still in packaging). They cost AUD $149 each, PM me with an offer if you are interested. Keep in mind the new 10k step encoders only cost $80 ea.

Mechanical drawing here:

http://www.wildcard-innovations.com.au/downloads/documentation/encoder_dim.gif

[iceman]

Is it worth spending extra if you already have 8192 step? I thought that the difference (in operation and pointing accuracy) would be negligble, or impossible to detect.

[Robby]

I wouldn't bother upgrading to 10k step encoders.
Unless your telescope is perfectly polar aligned and you had zero mount errors (virtually impossible) you won't notice the difference.
FYI. We used 4k step encoders on Mike's 10" with AN at SPSP and had excellent pointing!
Cheers

[Astroman]

Is it true you can get better encoder readings from gearing the encoder? Not directly attached to the mounts axis of rotation.

[Starkler]

The kit I have on mine has a gear on the centre azimuth pivot bolt and a cheaper 2000 step encoder to give 4000 steps effectively. This introduces potential inaccuracies with keeping the gears properly meshed, tolerances etc. Better to avoid gears if possible and use the highest resolution encoders attached directly to the axis of movement.

As for upgrading from 8192 to 10000 step encoders I wouldnt bother either as there would be little to gain.

[Howzat]

I've heard you can lose accuracy with encoders of higher resolution as the interface can "skip" because too much information is coming in, especially if you turn the scope too fast.
Gearing down the encoders would have the affect of slowing the rotation of the encoders and preventing this skipping.
of course if you have low res encoders (like mouse encoders) gearing up would have the affect of increasing tics per rotation

[Vermin]

As I said, I was "thinking about it". I'm not necessarily going to do it, but if someone wanted to take the existing encoders off my hands for an appreciable portion of the cost of the new ones, it might be an option. Especially as I have not installed them yet.

If not, I'll wait and see how they perform with the Servocat tracking system, but you are probably right, 2.2' (arc minutes) as opposed to 2.6' per step does not seem like much of an improvement.

[Smokey]

Any update yet Phil?
Have the DSC seen first light yet?
I,ll be interested in reading a run down of how they worked, how accurate they are ect

[astrodave]

I too buildt the Eck DSCs. I bought the board and preprogrammed PIC, and the clock from Mouser. I bought encoders and mounting hardware for my Meade eq from JMI - they were very nice (although I got hit with duty on bringing them in). I have this talking direct to my laptop with Belkin USB to Serial convertor. Works a treat..

[Howzat]

I only recieved the mounting kit today (I ordered it before easter) and was hoping to give it first light tonight.
But guess what..... :rain:

[Thiink]

I've ordered my board and PIC from FAR, just waiting for them to be delivered.

Howzat: mind if I ask where did you get the mounting hardware for the dob, and how much it was? Also do you mind if I PM you with some question on part numbers?

ps. what the heck is the "spark" test? :P

[Howzat]

I got the mounting kit from Sirius Optics here in brissy for $89. Bintel also supply them so they might be a better option for you. Wildcard Innovations (Argo Navis) sell them for $89.42 but as they source them from Bintel you may as well cut out the middle man.

PM away :)

[Howzat]

I took it as adding electricity and seeing waht happens