[mick4state]

The circuit needs to have 5 switches, each connected to a light, presumably LED. It can have any number of batteries or gates or anything, as long at it does the following. When the first 4 switches are thrown, their respective lights turn on. But the 5th switch (whichever of the 5 it happens to be) is thrown, that light does not turn on. More or less, it's a way to determine which operator had the slowest reaction time... kind of. I've played with gates and circuit boards and I just can't figure it out. Ideas?

Thanks.

-mick

[cwwozniak]

Without going into a whole lot of details, here is one possible way ...

- Have one side of all five switches (momentary is good) tied to a logic line that can be enabled or disabled via a separate control line.

- The other side of each switch goes to an S-R latch such that the latch gets set if the input line to the switch is enabled and the button is pressed.

- The output of each latch lights the matching LED for the switch using a buffer if needed to get enough current

- The output of each latch goes to a set of full adder gate combinations that counts the total number of switches that were closed.

- When the count reaches 4, the decoded adder output disables the common line going to all five switches. This prevents the fifth switch from activating its S-R latch

- Add another switch to reset all the S-R latches in preparation for the next round.

[mick4state]

Wow. It seems simpler than I thought it would be, but I'm having a terrible time drawing it up for some reason. With the switches in OFF by standard, then by turning on they send the 1 signal to the SR latch input, but what goes to the other input? And which output goes where? Do the other lights stay on after the 5th button is pressed? Sorry to be so confused... this is really not my strong area here. Thank you immensely though.

-mick

[bdimag]

I was thinking in my head - theres gotta be some way to count stuff in circuitry...

I don't know a thinh about the subject really.. but i tried to google a little.. atleast somebody knows what up.

cause my next guess would be 3 not gates for each switch - pair up the other 4 switches into not gates (NAND) and the outputs of the 2 gates to other gate, then to the LED..

which is like 15 gates.. *shrug*

and yes im making this up as I go..

[cwwozniak]

Originally Posted by mick4state

With the switches in OFF by standard, then by turning on they send the 1 signal to the SR latch input, but what goes to the other input?

The Reset inputs for all 5 S-R latches get tied to a sixth "reset" switch that will apply a logic "1" and turns off all the lights. This gets the system ready for the next reaction time test

Originally Posted by mick4state

And which output goes where?

The Q output would go to the adder circuit that counts the number of Q outputs that are high. Since the Q and /Q outputs are complimentary, which one you use to light the LED would depend on how the LED is wired and if any inverting buffers are used to drive the LED. The end result is you need the LED to be lit when the Q output is high or the /Q output is low

Originally Posted by mick4state

Do the other lights stay on after the 5th button is pressed?

Thank you immensely though.

The lights for the first four buttons will remain lit both before and after the fifth button is pressed. The first four players to press their buttons do not have to keep holding their buttons down to be counted. The only way to turn off the LEDs would be to press the separate reset button.

If you do not want to use a separate reset switch and people will be holding their buttons down the whole time, you could detect when all buttons are released and trigger a one-shot to reset all of the S-R latches.

And you are very welcome.

By any chance, is this for a school project or test? I have seen a couple of posts on newsgroups for other types of simple "game" logic circuits where people seemed to have posted the test instructions verbatim. It's one thing to ask for suggestions, but these people were expecting others to supply fully documented schematics for them.

[bdimag]

how was mine though? would I pass the test if I ever had to take one?

[cwwozniak]

Originally Posted by theoneandonlybd

how was mine though? would I pass the test if I ever had to take one?

Just using gates without any type of latching could work as well (and might actually be a bit simpler from a hardware standpoint). I believe you would only need Five 4-Input NAND gates to detect every possible combination of 4 buttons being pressed (or switch being flipped on) The gate that gets activated would then turn off the feed to the fifth switch (that is not connected to the gate). This would prevent that switch from activating any additional gates. and lighting their own LED.

[bdimag]

ya know, wiki said 1 or more inputs, but then their tables only showed 2 inputs - so I wasnt sure if there were 4-inputters.. although i am making this all up as i go, I didnt want to sound like a fool :P

[bdimag]

so what, B-? sweet

[cwwozniak]

Originally Posted by theoneandonlybd

so what, B-? sweet

Yes, It could be done with simple gates as you suggested. I did some sketching of possible circuits.

Just using five 4-Input NAND gates without any type of latching would would provide the needed detection of the first four people to close their switch. You would need some type of buffer/driver with enough current output to drive the LEDs.

The only down side of using gates would be if one of the first four people released their switch after the fifth person pressed theirs, they would end up being the one without the lit LED.

EDIT: Just noticed that some type of pull down resistors would also be needed for the gate input lines

[bdimag]

Originally Posted by cwwozniak

The only down side of using gates would be if one of the first four people released their switch after the fifth person pressed theirs, they would end up being the one without the lit LED.

good point. I'm going home

[JohnWill]

Time for a $1 uP, something like a PIC processor.

[mick4state]

In all honesty, my friends and I were playing a game where the slowest reaction time gets shocked, and we were wondering what circuitry would be involved in this game. We also wanted the last person to not get shocked, but rather simply be determined.

-mick

[mick4state]

I'll draw up a schematic and post, because I'm not 100% sure I'll get it right.

-mick

[mick4state]

I think this is how to post a picture...

This is all I was able to figure out. Help from here?



If that doesn't work... try here

http://i2.photobucket.com/albums/y33...et/circuit.jpg

Thanks

-mick