PAW4 - RetroTime

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PAW4 - RetroTime

Postby matseng » Sun Dec 30, 2012 1:07 pm

As mentioned in an earlier post I'll try to do one small PCB project every week and then send for PCB's of it every Monday.

Next week I'll do a slightly more advanced project than a simple breakout. I had this idea of making a very complex outline on a PCB and see if Seeedstudio and their fab house would accept it. I'm following the series Supernatural where the protagonists often stay at old motels with a lot of 50-60-70'ies decorations and furniture in them, so I decided to to a wall clock with a retro-inspired design.

The clock will have twelve "arms" each with a RGB PLCC6 (5050) SMD led at the end where hours, minutes and seconds will be represented by a color each.

I'll keep all the parts except for the leds on the backside to give an empty front where I can put some retro-pattern on the silk layer to enhance the retro feeling of it.

This week I have to go up to a 10x10 cm PCB instead of the 5x5 that the PAW designs should use, but I think it will be worth it...

RetroTime-gerber1.png
A lot of cutting will be required to get this shape...
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Re: PAW4 - RetroTime

Postby matseng » Sun Dec 30, 2012 1:24 pm

Yes, that's a nice idea... Have the leds on the back side of the pcb as well, and then have it mounted 1/2 inch above a white frame that reflects the light from the leds. That might actually look cooler.... and not so modern with visible leds.
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Re: PAW4 - RetroTime

Postby systemstech » Sun Dec 30, 2012 11:04 pm

matseng;

What µc and clock chip do plan on using?
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Re: PAW4 - RetroTime

Postby matseng » Sun Dec 30, 2012 11:17 pm

Not sure yet. Probably a small cheapass 20-pin PIC like PIC16F1829, I don't need any usb or fancy stuff in it for this project. I could go with a atmega168 as well, but that would feel so "Arduino" :-)

Then I'll have 6 latches 75HC573 in SSOP so I can direct drive all leds, no multiplexing required.

Haven't decided on the clock chip yet either. Any with battery backup and i2c would be ok..

Route-SSOP-573.png
I need to remove two pads from the footprint so I can route a wire there.... :-)
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Re: PAW4 - RetroTime

Postby systemstech » Sun Dec 30, 2012 11:29 pm

I have a lot of the rgb plcc-6 5050's, about 10 ds1307, 4 ds3231, 5 atmega8a all smd. Are going to use only smd parts?
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Re: PAW4 - RetroTime

Postby matseng » Sun Dec 30, 2012 11:36 pm

The ds1307 seems like a reasonable choice... But maybe I can leave an empty footprint for a high precision ds3231 as an option.

Yes, SMD only is a must if you want the top to look clean and nice...

What do you think about MickM's idea of having the leds on the back to get indirect reflected light from them instead of having them on the top?
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Re: PAW4 - RetroTime

Postby systemstech » Sun Dec 30, 2012 11:49 pm

What do you think about MickM's idea of having the leds on the back to get indirect reflected light from them instead of having them on the top?


I think that would be cool. Are the leds going to shift or blend in color from number to number?
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Re: PAW4 - RetroTime

Postby matseng » Mon Dec 31, 2012 1:07 am

I'm going to try to get a blending effect.

If the minutes is green and on the 3'rd led (15 minutes past) and the seconds is red I want the 2'nd led to be fully red and then the 3'rd led will become more and more yellow (mix red/green) and the 2'nd led to be dimmer and dimmer during the 5 seconds it takes for the seconds to go to the 3'rd led.

So it will be a smooth transition between the leds - at least for the seconds. Maybe also for the minutes...
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Re: PAW4 - RetroTime

Postby matseng » Mon Dec 31, 2012 1:44 am

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Re: PAW4 - RetroTime

Postby matseng » Mon Dec 31, 2012 1:30 pm

Schematic and routing almost done....

Schematic.png


The routing is almost as retro as the visual design of the clock. I've mostly routed it with the free-angle tool so it almost looks like I've done it with tape as we did back in the 70'ies before computer pcb cad.

BottomAlmostDone2.jpg
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Re: PAW4 - RetroTime

Postby sqkybeaver » Mon Dec 31, 2012 1:36 pm

for the coin cell i suggest changing the center pad to a circle the size of the cell, the solder mask around the pad can prevent contact with the pad.
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Re: PAW4 - RetroTime

Postby Bertho » Mon Dec 31, 2012 2:50 pm

The inner angles of the cutouts are drawn as (almost) 90 degree. The milling will not allow sharp angles, but is limited to (often) 1mm radius.

Does the PCB manufacturer accept inner angles this sharp or do you need to make remarks on the outline to get it made right?
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Re: PAW4 - RetroTime

Postby AndThen » Mon Dec 31, 2012 6:10 pm

Are you past dead line already?

If not I propose one small change. To the led drive traces nudge them apart and add "solder jumper" to each. So the arms can be sawn off and extended with wires.

Combined with the leds facing the wall concept you could then put it behind any random sized picture/object and have a unique clock.
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Re: PAW4 - RetroTime

Postby matseng » Mon Dec 31, 2012 10:37 pm

sqkybeaver wrote:for the coin cell i suggest changing the center pad to a circle the size of the cell, the solder mask around the pad can prevent contact with the pad.


Done. I usually put a small blob of solder in the pad to raise it up a bit, but here there's no other tracks passing under the battery holder so the increased pad size -method works fine here.

Bertho wrote:Does the PCB manufacturer accept inner angles this sharp or do you need to make remarks on the outline to get it made right?

I've no idea... I hope that they will mill as close as possible to the outline in accordance to their bit size, and that they leave "unreachable" board rather than taking away extra to reach the edge. I'm sure they will complain if it will destroy the pcb. I fear that asking them (Seeedstudio) how it should be done and what they can handle would just result in some random incomprehensible google-translated reply. So I'll just try and see what happens. :-)

AndThen wrote:If not I propose one small change. To the led drive traces nudge them apart and add "solder jumper" to each. So the arms can be sawn off and extended with wires.

That's a fun idea. Why not.... Were would the best cutoff point be you think?
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Re: PAW4 - RetroTime

Postby matseng » Tue Jan 01, 2013 2:43 am

Ok, only a connector to the power is left to add. But I can't decide what type of contact that would be best... I'm open to suggestions.

BottomDoneExceptPower.png
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