Voltage regulator.. or Help the noob!

[BlinkingLeds]

hi sorry if this will be a really dumb question but here it is : why not use a 220v to 12v transformer and forget about the battery?
If mains power is not available there then how about a small ~20wats diy solar panel and a simple charging circuit for the battery so that you don't have to care for the power ever again?

 

[davenn]

hi sorry if this will be a really dumb question but here it is : why not use a 220v to 12v transformer and forget about the battery?

g'day mate .... maybe you didn't understand what the power supply and motor was for ?
Its for driving a platform that a camera sits on for astrophotography ( nitetime star photos)
have a look in the link in post #1

this is likely to be done out in the middle of nowhere away from all the bad city lights
.... so no mains power available

If mains power is not available there then how about a small ~20wats diy solar panel and a simple charging circuit for the battery so that you don't have to care for the power ever again?

not really needed ... the battery gets charged up before going out for the night of photography
and there isn't any sun at nitetime
If I'm going away for several days of astrophotography, I will usually just charge my portable SLA battery off the car battery .... saves a lot of problems

if you look at the circuit shown, its designed to drive the motor with adjustment to get the correct rotation speed

cheers
Dave

 

[BlinkingLeds]

good day to you too (actually it's good night here as i'm also from Greece )
I was under the impression that he will leave the camera there and rig it to automatically take pictures that way he could leave the battery there instead of carrying it all the time.
well then about the speed control how about a simple pulse width modulation? would be much easier i think.. not sure of the speed resolution though but maybe it will do the job and would be a nice project to learn 555 was the first ic that i learned how to use after mosfets

 

[davenn]

Hi BL

No, he would always be near the camera. exposure times ( long ones ) may range from say 30 seconds to maybe 5 to 10 minutes
The camera will be in full manual mode so he will start and end the exposures depending on the desired length of exposures

The speed control is primarily done by a motor that is internally geared to a very low rotation speed 4 - 5 rpm
then a couple of external gears to bring the main shaft down to 1 rpm

Its a tried and proved system used by many astrophotographers worldwide

The whole idea of the very slow speed of the platform is so the camera will track the movement of the stars across the sky
so that you end up with points of light instead of star trails

cheers
Dave

 

[eheadj]

Guys, anyone??

Anyway I have done some homework [not nearly enough] and concluded to the following:

Let me recap first:

a) I want to pulse an Easy Driver V4.4 which will drive a 200 step/rev [1600 step/rev microstepping] stepper motor.

b) I want to create the pulse with the use of a crystal oscillator and frequency division.


Please feel free to correct me! This is by far the most difficult attempt so far in electronics for me.


1) I could use a 1.8432 MHz crystal [ I found this one on ebay: http://www.vanlong.com/download/HC49U.pdf ]

2) Make a "Pierce Oscillator" circuit [ Something like this:

]

3) Divide the 1.8432MHz frequency by 1152 (1.843.200/ 1152 = 1600) with the use of a divide-by-n counter [ Something like this: http://www.ti.com/lit/ds/symlink/cd4059a.pdf ]


Questions:

0) Does all of the above make any sense? [My experience in electronics counts less than 2 months and maybe I miss very important stuff needed to implement all this]

1) Is this all possible to do without an oscilloscope?? [critical]

2) The crystal does not mention (I think) the Voltage of operation in the datasheet. So at what voltage should I operate it? Are there limits?

3) I can't [with my current knowledge] decide as for which IC should be used to make the frequency division.

By taking a look to this link [ http://www.digikey.com/product-search/en?Cat=2556429&k=divider] from the "Long duration timers - Notes for beginners" post by *steve* in this forum, I lost it completely..


Directions for the blind please..


I did some experimenting with a 555 timer circuit and a 14 stage ripple binary counter and all went well except for the fact that even though the IC is a BINARY counter the leds

blinked FOUR times for it to go to the next stage??? Unexplicable to me..

Then I did a bit more experimenting with a ceramic resonator (400.000KHz) and the same 14 stage ripple counter and it NEVER worked. Not even 1 led ever blinked... Will try again.


Oh, I forgot.. The purpose for all this is to be able to run the crystal - divider circuit on common e.g. 1.5V pack or 9V batteries
and the Easy Driver on a Sealed Lead Acid battery so that the whole above project becomes as accurate as possible and at the same time as portable as possible..

Ideas, suggestions...

Thanks,
eheadj