reflex tester game?

You could use a signal that indicates that you are counting down, then if a button is pressed while this signal is active you can generate an error condition that would indicate who the guilty party was. Without thinking through the details, it seems to me that you will need similar control signals to latch the first button press and lock the others out, so you may already have something that will work.

How were you planning on implementing this circuit? I might suggest that you consider a microchip PIC, but it can be done other ways too.

I'm not up to speed with PICs yet but am comfortable with the more traditional 555's and such. I think it could be done this way but I'm no expert here.

Pete

Yes, your circuit should be simple enough to implement with timers, discrete logic, and some small IC counters and flip flops. If you are fairly neat in your workmanship you can probably even get away with building the circuit on a breadboard and then fabricate a simple circuit board. To me this sounds like a good fun project that would be challenging but do-able.

How familiar are you with truth tables and minimization through Karnaugh maps? What about state machine diagrams? If you aren't very familiar with this, I would recommend that you get a book on digital logic and switching. Probably about the time you get half way through the book you will have everything you need to do this project. A book on digital electronics geared towards hobby work would likely even have projects to build a bread board system. I have a book on my shelf "Digital Electronics Guidebook", by Mike Predko, which I believe I ordered through Amazon. This type of book may be a good choice for you. It covers the digital and analog electronics including transistors, counters, flip flops, 555s and up to simple processor based stuff.

With the bread board approach, you can then build up a small section, such as one of the truth tables or state machines, counters, etc and experiment with each one seperately and then start putting them together. If you don't have one, you can probably get a bread board at radio shack or an online company. I had one floating around but I can't find it to tell you where I got it, but I think it was something along the lines of "circuit specialists".

The way I would recommend starting is to think about the inputs you need / have and the outputs you want. Then either draw a set of truth tables and or state transition diagrams. This will give you the basic logic equations, which you can the minimize to reduce the number of gates, wiring., and cost.

If you are ambitious enough, this would be a good PIC project. I have seen books on PICs even in places like Barnes and Nobles and Borders. I say that this would be a good PIC project because a lot of the functionality you are after would be pretty easy to implement with simple software. You could then use the IO pins of the chip to drive the LEDs or drive some decoders, etc.

Yeah - people have been building these things for decades:

Cheers! Rich

hmm you need to disqualify anyone who presses early so there's 3 states for each input unpressed, pressed early, and pressed on time to store 3 states takes 2 flip-flops make 4 of these... "input units" (reset)___________________ | ___ +-|R Q|--- cheat (early)------------|~~\\ | | _| | & )--|-|S Q|O-----|~~\\ out __ +--|__/ | ~~~ | & )--- (press)--| \\ | | +---|__/ | & )--+ | ___ | (enable)-|__/ | +-|R Q|--+ +--|~~\\ | | _____ | & )----|S Q| (early)------------|__/ ~~~ now, how to hook the 4 input units together.

_____ the (early) , (early) (reset) and (enable) inputs are common among all the input units, (press) is wired to go high when the button is pressed. reset goes high momentarily to clear the output and start a new game (attach it to the decade counter output 0 pin) ... _____ (early) is inverted (early) or vice-versa (attach (early) to out 9 (or whechever out on the decade counter means _____ press now) and use an inverter (or out 8) to get (early) wire the 4 outs to a 4 input nor gate (or equivalent) and the output of that to enable. how it works, after reset (early), and (enable) are both high and so any signal on (press) will set the upper flip-flop. _____ once it's time to press early goes low (and (early) goes high) now any high signal on (press) will pass through the lower and gate and set the lower flip-flop if the lower flip flop is set and the upper is not set that's two high outputs to the last and gate which makes out go high, that makes a high input to the 4 input NOR gate (discussed above) which makes enable go low blocking all the buttons from effecting any further flip-flops until the game is reset.

the winner is the one with a high "out" (attach the indicator this output)

Any cheats will have a high "cheat" output.

if you want the game to restart autommatically after a winner has been found attach reset further down the decade counter and use a 4 input and gate to detect the case when all four players cheat.

the "christmas tree" traffic lights used for starting drag races have a random delay between the yellow and the green light you may want to consider implementing this feature in your game so that players must react to the "go" light instead of just judging when it will light,

Bye. Jasen

How about a random timeout that drops a ruler? The victim puts their fingers near the 12" mark, and a solenoid is used to release the thing. The score is where they grab it, in inches...

You can get solenoids here:

This one is a 12V DC relay, which means you'll need some kind of voltage source. This one might work (from the same guys:)

(check the current rating of the solenoid)

You can either just have a little normally open button to work it, or a timer of some kind.

Here are some buttons:

If you think you want a random timer circuit, I can design one that will work for you, but the button is probably the easiest, and if you put it at the end of two wires, you won't have a problem hiding the activation.

You'll have to build the stand, get the ruler, and figure out how to reset it...

You can do this with a dollar bill (or $100, if you're feeling frisky. ;-) ).

Have the subject stand or sit next to a table, with their forearm resting on it and their hand sticking out over the edge. Have them hold their thumb and forefinger about 2" (50 cm) apart, and hold the bill in your own fingers, where the middle of the bill is in between their thumb and finger. Drop the bill.

No one can catch it.

by now you've seen the circuit I desiged yesterday there were 4 and gates and two flip-flops per player plus the counter and the clock and the or gates etc.

call it 9 ics for the whole unit including the decage counter, 4 input nor gate (or gates) and 555 timer.

with a microcontroller you could do all of that in a single chip.

you'd need to know how to program it, and make/buy the hardware to load the program into it (there is free software available) ...

Bye. Jasen

Nice!!

Plus the follow up with pointers to the parts ... great!

Ed

(You could also remember the Benson & Hedges 101 commercials.)

OK, it was a typo that I corroborated by way of brain fart. :-) (Hey, I'm an American! Those damn metric things are UNNATURAL!)

Thanks! Rich

Nah. The *count by tens* thing is natural enough. It's the converting back & forth that sucks.

If we'd just bit the bullet in 1917 when the Industrial Age was hitting its stride and the i18n thing was warming up, it would all have been so much easier.