From: Philip A. Marshall
Subject: Re: Logic simulator for kids
References: <3dd9fae3.50578103@News.xtra.co.nz> <email@example.com>
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Date: Sat, 23 Nov 2002 03:05:24 GMT
NNTP-Posting-Date: Fri, 22 Nov 2002 20:05:24 MST
On Tue, 19 Nov 2002 16:25:53 GMT, "Sir Charles W. Shults III"
>"Gary Tait" wrote in message
>> On Tue, 19 Nov 2002 09:45:29 GMT, firstname.lastname@example.org (Mike
>> Harding) wrote:
>> >Nah! Give him the breadboard and the real stuff.
>> >You wouldn't give the son of a carpenter a picture
>> >of a saw would you? :)
>> But TTL instead, a little more forgiving IMO.
> On this point I would agree. TTL is pretty much bullet proof. It can
>directly drive LEDs at the outputs (and you really don't need much more than
>that to demonstrate most working circuits to a kid) and it can be used without
>worrying greatly over floating inputs. You can actually use the gates with no
>more than some grounding wires, and this is something a kid can do easily.
> You would be surprised at what you can build with a 7404 and a 7400.
pfft. get him a couple hundred 2n3904s and a bunch of 1K resistors
and make him WORK. :-D and then it won't matter if he blows anything
up, because it's cheap to replace.
that's what i did. in the end, it gave me a lot more insight into
logic design than ICs ever would have. i had a course at university
that the lab portion consisted entirely of wiring up 74xx series
devices and it was really boring.
teach him how transistors work with large signals, show him how to
make inverters, and make him figure out NAND and NOR gates.
make sure you get him a BIG breadboard though. i made an 8-3
multiplexor that fed into a 3 to 8 decoder (to mimic a simple
communications system), and there were hella lots of transistors.