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Old 3rd September 2012, 02:05 PM   #1
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Default Discrete Logic ABX Switch Box

I'm the kinda guy who designs circuits when I have nothing to do.
So recently I designed an ABX switch box using discrete logic.
Here's my Conceptual Schematic:

Click the image to open in full size.

It seems to work fine in my simple Java circuit simulator, but I'm not sure if this will really work.
So is there anyone with electronic experience who can give me some feedback?
(anything wrong, improvements?)


Notes:
Relays aren't drawn here because this simulator doesn't have the reed relays I'll be using.

The "ABX Switch" has a center-off position.
The "Randomize X Switch" is a Push-switch.

The "X" random is generated using a square wave and a human controlled "hold" switch.
Picture it like a wheel of fortune or slot machine if you will.

The "OR" gate in the center that's connected to its own input is used to hold the "X" status,
so that the status of "X" will be the same every time until the "Randomize switch" is pushed

EDIT:
I may switch the NOR gate for an OR gate and Discrete CMOS NOT Gate (Using 2 MOSFETs),
because Logic gates comes in packages of 4s.
Anyone know a small complementary MOSFET pair I could use?
(No surface mount packages)

Last edited by b1o2r3i4s5; 3rd September 2012 at 02:12 PM.
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Old 3rd September 2012, 03:07 PM   #2
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From a user point of view, what does he do to change from A to B to X? Reversible? How is the "final answer" and the actual option presentation recorded?

A nice analog ABX box would be a good thing to have!
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Old 3rd September 2012, 03:15 PM   #3
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Quote:
Originally Posted by SY View Post
From a user point of view, what does he do to change from A to B to X? Reversible? How is the "final answer" and the actual option presentation recorded?

A nice analog ABX box would be a good thing to have!
The ABX Switch has 3 states, the 2 sides will give state A and B while the center position will give state X.
The states are changes simply by flicking the ABX switch.

The actual state of X can be seen via the "Actual status indicator" (refer to schematic), This is normally hidden from the user.
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Old 3rd September 2012, 03:18 PM   #4
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Thanks. If it's hidden, how is the choice recorded? Tough without a microcontroller... Could you add a few gates, let the user guess after he's switched back and forth enough times, and then a red or green LED comes on depending on whether he's right or wrong? The user then has to record his track record, so the controls for a third party aren't tight, but it can be useful as a training tool or individual curiosity (like the ABX function in foobar).
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Old 3rd September 2012, 03:59 PM   #5
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Quote:
Originally Posted by SY View Post
Thanks. If it's hidden, how is the choice recorded? Tough without a microcontroller... Could you add a few gates, let the user guess after he's switched back and forth enough times, and then a red or green LED comes on depending on whether he's right or wrong? The user then has to record his track record, so the controls for a third party aren't tight, but it can be useful as a training tool or individual curiosity (like the ABX function in foobar).
Unfortunately, it will have to be recorded by the user after guessing and before randomizing for the next guess. (Take a peek inside/behind the box maybe?)

While it's not hard for me to add a few memory registers to record X states (4 maybe), it'll get quite complex construction-wise without PCBs.
Since the whole point of this is that Cs are not required, people who don't have access to C tools probably can't make PCBs either...
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Old 3rd September 2012, 05:50 PM   #6
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Just made a practical schematic:

Click the image to open in full size. Click the image to open in full size.

Note: The ABX switch shown is a SP4T Rotary Switch because I couldn't find a SPDT switch with center-off in the library.
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Old 23rd September 2012, 02:09 PM   #7
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Quote:
Originally Posted by SY View Post
Thanks. If it's hidden, how is the choice recorded? Tough without a microcontroller... Could you add a few gates, let the user guess after he's switched back and forth enough times, and then a red or green LED comes on depending on whether he's right or wrong? The user then has to record his track record, so the controls for a third party aren't tight, but it can be useful as a training tool or individual curiosity (like the ABX function in foobar).
Well, You asked and I delivered!
Here's an extension of my previous design WITH Data logging!
It supports up to 8 testing trials with trial # indication AND the X state in each trial! (Green LED = A, Red = B, yeah... i know you can't see it.). Pressing "Randomize X" again at the 8th trial will reset all recorded data.

Click the image to open in full size.

Last edited by b1o2r3i4s5; 23rd September 2012 at 02:11 PM.
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Old 23rd September 2012, 02:22 PM   #8
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Duuuuuude!!!!
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Old 23rd September 2012, 07:35 PM   #9
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Alright, Practical Schematics Rev.B:
Click the image to open in full size.
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Old 23rd September 2012, 07:41 PM   #10
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If you do a PCB, I'm in!
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