I'm with Chuck. What do you want to teach?
For someone with any kind of digital logic knowledge, the counter thing
would be a snap. Lots of ways to make it, and also lots of ways to
modify the function with a little creative wiring.
But for teaching the simple example you talked about, I also like the
relays with capacitor timers. That would be both simple to teach and
simple to understand.
bp
<part15sbs{at}gmail{dot}com>
On 1/9/2015 9:12 AM, Chuck McCown wrote:
In my mind, a 555 timer is more difficult to understand as it has a
comparator and flip flop inside amongst more things.
I guess it depends on the opinion of what is easier to understand.
In my mind, relays are easier to understand than logic in chips like
that.
For example, you can have a push button discharge a cap. That cap
would be across the windings of a relay. Big cap fed via a resistor.
Push the button and the relay opens until the cap charges back up.
That is a pretty simple timer circuit. t=RC.
If you want to cut down the size of the big cap and obvious short life
of the pushbutton, you can go one step further and put a transistor in
the circuit etc etc. In my mind that is much simpler and easier to
understand than a 555.
However, if you are looking for a simple block diagram understanding,
the 555 is the way to go.
I realize that I may not have the ability to look at these things as a
kid would look at them. What is simple to me may not be simple to
them and vice versa.
-----Original Message----- From: Mark - Myakka Technologies
Sent: Friday, January 09, 2015 10:04 AM
To: Chuck McCown
Subject: Re: [AFMUG] OT - EE help please
Chuck,
I'll be working with the kids again tonight. Hopefully we'll have
time to go in a bit more detail. The 555 is appealing being it can
do many things. We can use it as a timer, we can use it to flash
leds, etc. The kids will only have to learn about the 555, caps and
resistors.
