Jeopardy Circuit Question

[NodakBarnes]

I have a question about a Jeopardy Circuit I found on the internet and
decided to build. To start, here is the link to the circuit so you
understand what I am talking about:

http://members.shaw.ca/roma/twenty-two.html

I have constructed the six button circuit and after exhaustive testing
and reconstructing on the breadboard numerous times finally got fed up
with it and modelled it in Multisim 7. Come to find out, it didn't
simulate properly in Multisim either. Looking at it more carefully with
a logic probe I came to discover that the two NAND outputs (pins 6 and
9) of the 4023 being "ganged" together does not work. I "isolated" both
outputs by feeding them through an OR gate via a 4071 and it then
worked as advertised. First, is this the proper approach to fix this
problem? And also, I was wondering if the resistors (R1 - R6)
supposedly used to clamp down the inputs in case of noise are really
needed?
Any help appreciated...Thanks!

Wallace Barnes

 

[OBones]

I think you could have used two diodes instead of a OR gate. It takes
less space and less power, and should work just as well.

 

[Tom Del Rosso]

I have a question about a Jeopardy Circuit I found on the internet and
decided to build. To start, here is the link to the circuit so you
understand what I am talking about:

http://members.shaw.ca/roma/twenty-two.html

I'd like to know what CAD program was used to draw those diagrams, so I
could avoid it like the plague.

Here's a circuit, for 2-8 inputs, that was posted in abse a few years ago.

http://mysub01.home.att.net/jeopardy_8-way_by_Daniel_Simon.gif

 

[John Woodgate]

I read in sci.electronics.design that Tom Del Rosso

I'd like to know what CAD program was used to draw those diagrams, so I
could avoid it like the plague.

The six-button graphic includes a filename 'jeopardy2.sch'. That may
give a clue!

The diagram are both schematics and PC board layouts, and serve neither
purpose very well.

 

[JeffM]

I'd like to know what CAD program was used to draw those diagrams,

The six-button graphic includes a filename 'jeopardy2.sch'.
That may give a clue!
John Woodgate

Then again, he could have renamed them.

My guess would be some variant of Visio.
It is clueless about **wires** and **components**.

 

[[email protected]]

You could wire 4023 pin 6 to 11, pin 9 to 12 separately, no parts
required. R1-6 are pulldowns, without them the inputs float.