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Teaser/preliminary pic for upcoming project...

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LAN_403

ConKbot of Doom

Sat Feb 17 2007, 08:20AM

Registered Member #509 Joined: Sat Feb 10 2007, 07:02AM
Location:
Posts: 329

Nothing too fancy but it will let me put together a few different areas into one project using a PIC.
In the attached picture,
From the top,
PIC 16F877A, one I had laying around, may or may not be used, might pick another uC.
Underneath that, (in the IC tube of 20 SOIC-8 chips)
Fairchild FAN7382M

Down and to the right of that, a nice pile of RGB LEDs

The single DIP16 chip next to those, is a MAX232 (or another variety of the same family)

Below that is 5 TLC5940 chips.

To the left of those is a BQ4285 kind of dated but it'll do what I need.

To the left of that is 8 mosfets, n-channel, 60v, enough amperage, nothing special here...

Above that is the stepper motor.

Anyone else like what they see? Any guesses, no cheating if you browse bit-tech too

Dago

Sun Feb 18 2007, 08:36PM

Registered Member #538 Joined: Sun Feb 18 2007, 08:33PM
Location: Finland
Posts: 181

Sounds like a computer controlled RGB led matrix I suppose :P

AndrewM

Mon Feb 19 2007, 12:04AM

Registered Member #49 Joined: Thu Feb 09 2006, 04:05AM
Location: Bigass Pile of Penguins
Posts: 362

Obviously a helicopter.

Sam

Mon Feb 19 2007, 12:19AM

Registered Member #227 Joined: Mon Feb 20 2006, 10:47PM
Location: Cambridge Ontario, Canada!!
Posts: 127

no way, Its a nuclear fusion reactor controller...

Is that legal where You are?

ShawnLG

Mon Feb 19 2007, 04:33AM

Registered Member #286 Joined: Mon Mar 06 2006, 04:52AM
Location:
Posts: 399

Its a PIC controlled SSTC with multy color LED for 7331ness. I guss he will use the magnet wire inside the stepper moter for the secondary.

Electroholic

Mon Feb 19 2007, 05:28AM

Registered Member #191 Joined: Fri Feb 17 2006, 02:01AM
Location: Esbjerg Denmark
Posts: 720

its a RBG POV display

Steve Ward

Mon Feb 19 2007, 06:28AM

Registered Member #146 Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055

Is the stepper bipolar or unipolar? Thats very important.

Steve Conner

Mon Feb 19 2007, 10:50AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Is it a propeller clock with full colour display?

ConKbot of Doom

Thu Feb 22 2007, 11:40AM

Registered Member #509 Joined: Sat Feb 10 2007, 07:02AM
Location:
Posts: 329

ShawnLG wrote ...

Its a PIC controlled SSTC with multy color LED for 7331ness. I guss he will use the magnet wire inside the stepper moter for the secondary.

Tesla coils go in the tesla coil subforum

Steve Ward wrote ...

Is the stepper bipolar or unipolar? Thats very important.

That particular motor is bipolar, but I believe 6 or 8 wires actually do come out of the casing, with only 4 hooked to the connector. I may end up using another one.

Steve CÃ¸nner wrote ...

Is it a propeller clock with full colour display?

Thats what I certainly hope it will be, certain things may have to change, like a different stepper motor, the one pictured is 400 steps/rev. I have some 48 steps/rev motors I got in the mail.

Considering the amount of data needed for 16 bit color, if I want to do full graphics (I.E. be able to load a bitmap onto it to display, not just multi color text) I'm going to need some RAM too, ~300 bytes on a PIC wont do for a 16x200 16bit color image

One question though, someone on another forum suggested that speed would be an issue with the stepper motor, saying the most he could get out of a stepper motor he was playing with was ~120RPM, overdriving it with 15v instead of 5v and it was a 9 degree/step motor, I find a maximum pulse rate of 80 pulses/sec to be quite low, especially reading other web sites, Ive seen numbers in the 400's up to 1500 pulses/second if not more, and motor drivers that can handle 25000 pulses/second.
I know it all depends on the motor inductance and load, but what sort of pulse rates would be a more real-world estimate?. 960 steps/second with a 7.5deg/step motor would give me 20 FPS which should be sufficiently smooth, 480 steps/sec would be 10 FPS which would be about the lowest I would want to go. If I cant get that, I'll just use a DC motor with a reduction, and a photo-transistor/IR LED to index the arm, and a PID loop on the controller for the motor to maintain a constant speed.

Its gonna take a while to build between limited time, to work on it, and not having any real experiece in any of these areas, but I think I'll be stubborn and actually get this done.

Steve Conner

Thu Feb 22 2007, 12:21PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I think the noise of a stepper motor running at 960pps will drive you crazy in about a half hour. Wheeeeeezzzzzzzzz.... Probably best to use a DC motor with an optical or magnetic index pulse thingie, it will be much quieter.

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