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Small/cheap Full-Adder (2bit)

Archive: 16 posts

Here's my small full-adder

http://bennyland.com/lbpadder.jpg

(if the image doesn't load, it looks like this

[piston][glass block][piston][glass block][piston][glass block with two switches]
[four keys]


I've heard that you can do this even simpler, maybe even with wheels instead of pistons, but this is all I could come up with.

The three inputs are the pistons, the outputs (carry and sum) are the mag switches. Make the pistons 0.1 and play with it so that they extend and contract to where your truth table looks like this:

If all three pistons are 'off', your C and S are off
if only one piston is 'on', your S is on, your C is off
if two pistons are on, your S is off, your C is on
if three pistons are on, both S and C are on

Enjoy! Let me know if/where you end up using it 		2010-05-24 18:15:00

Author:
anverc
Posts: 12

Nice, but here's your challenge:

Do it with only one key and two switches (the absolute minimum possible for the 'sum' and 'carry' outputs). Hint: if you're only using one key, then it darn well better be able to move...

Super bonus points if you can do it using only wobble bolts while still only using one key and two switches.

I'll post back in a few days... 		2010-05-25 01:30:00

Author:
comphermc
Posts: 5338

Hey there!
I'm actually curious to what it does! What can you use it for?		2010-05-25 01:46:00

Author:
standby250
Posts: 1113

It basically adds in binary. 2010-05-25 02:47:00

Author:
comphermc
Posts: 5338

After getting this message (i was in messing around with addition/subtraction of 1's) I decided to look back on how you may have done the 4-piston/1-key you spoke of in the TI LBP thread and was able to slightly modify mine in order to beat your best with a 3-piston, 1-key, although it took around 3 minutes of tweak,tweak,tweak.... Below is the video of it in action.

I don't understand bolts enough to figure out how to use them like rtm's apparent bolt action full-adder - i've only really been playing with this for a few weeks at this point. Gonna try figuring that out soon.


http://www.youtube.com/watch?v=8Wt9y7uqhD8


Nice, but here's your challenge:

Do it with only one key and two switches (the absolute minimum possible for the 'sum' and 'carry' outputs). Hint: if you're only using one key, then it darn well better be able to move...

Super bonus points if you can do it using only wobble bolts while still only using one key and two switches.

I'll post back in a few days... 		2010-05-25 03:15:00

Author:
anverc
Posts: 12

what comphermc said - I'm trying to get my lockbox level to allow for increment and decrement on the 7-segment display... In order to do that I need to ditch my emitter based adder and come up with an actual full-adder that I can then pass in a carry for signage. I still haven't figured out how i'm going to store the output briefly before resetting my initial storage - right now i'm dealing with the numbers going all over the place once it starts up.

here are some interesting articles you might want to read (also read rtm's logic blog where he basically tells you to forget about the contents of these articles - I believe it's important to know the contents of the articles but in addition realize that they'll only help you with truth tables, implementation this way is not a good idea if you care about thermal)
http://www.play-hookey.com/digital/adder.html
http://www.play-hookey.com/digital/binary_subtraction.html		2010-05-25 03:19:00

Author:
anverc
Posts: 12

Ok comphermc ... Here's one using wobble bolts - I gotta say, I would NEVER use this unless I was forced to - the wobble bolts seem to lose their barring at the drop of a hat

Is there a better way of achieving this?


http://www.youtube.com/watch?v=aCqD3Hcowg4		2010-05-25 04:23:00

Author:
anverc
Posts: 12

Wow, very cool. It does best my design, but not quite the bolt design. I will post that up tomorrow. I have to head off to bed for work early in the morn'.



Edit: You sneeked in there. Not quite. The key to it all is for one of the switches to feed back into a wobble bolt.

Edit2: Actually, that works just fine. Just shrink it down in size and use polystyrene or dissolve for the wheels and you should get rid of the springiness.

Lastly, try not double posting (site policy). Instead, use the 'Edit Post' button.

2010-05-25 04:28:00

Author:
comphermc
Posts: 5338

can't wait to see your designs (i'd like to see both as I'm sure the piston one is a little more elegant than mine) - need to go to bed myself.

sorry about the double post - I did hit edit, but may have accidentally hit the back button on the mouse at the same time or something.		2010-05-25 06:02:00

Author:
anverc
Posts: 12

Lol Comph, I think you like this guy already! 2010-05-25 06:09:00

Author:
agrx
Posts: 192

I'm lucky he threw a challenge down - I had given up on both the 1-key piston version and the wheely one but then a challenge happened... 2010-05-25 06:17:00

Author:
anverc
Posts: 12

Sorry I didn't respond to your initial message, I accepted the PSN friend request assuming I'd see you online,

The wobble bolt one looks similar to mine, can't get the vid to load, although I got around the instability by stacking 2 wheels in front of the dark matter and 1 wheel behind, with the DM thin, so the front two wheels are DM-thick-thin, to ensure the ratio of weights.

The issue of course is the wiring, although seeing as each input is treated equivalent, you don't actually have to worry about which wire goes to which wobble.		2010-05-25 09:46:00

Author:
rtm223
Posts: 6497

Thanks RTM - I missed you by about an hour lastnight, but that ended up being a good thing because it forced me to hunker down on comph's challenge

Can't wait to see both of your adder designs - your logic blog really helped me out. It has been a long time for me since doing this stuff with electronics - which either helped me or hurt me, I'm not sure yet. But once your teachings on forgetting the electronics side of things finally clicked (it took a while) I started seeing things in a much more exciting light.		2010-05-25 14:08:00

Author:
anverc
Posts: 12

Bah, didn't have time to post mine tonight.

I will say that your design is more elegant and is more thermo-fficient. In addition, it would make me feel all dirty to post rtm's design.		2010-05-26 04:00:00

Author:
comphermc
Posts: 5338

it would make me feel all dirty to post rtm's design.

Huh? Is it better or worse than yours anserc's?		2010-05-26 04:06:00

Author:
Incinerator22
Posts: 3251

It's very, very similar. I sent mine to anserc last night for him to have a look over although I'm never sure whether those get there or not.

If anyone wants to post mine they can. I won't have time.


Just this moment I've come up with a 3 piston design that would occupy the same thermo (3 pistons, 3 moving parts, 2 switches, 1 key). If anyone wants a hint as to how to achieve that, it shares a common design element with my mutual exclusion switch.		2010-05-26 09:47:00

Author:
rtm223
Posts: 6497


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