# School Project Help!

Discussion in 'Homework Help' started by Transon, Nov 4, 2013.

1. ### Transon Thread Starter New Member

Nov 4, 2013
1
0
Okay, I've recently began to study electronics on school and tomorrow I got a BIG test, and I need big help because I cant seem to understand how I start the circuit.

Its a Binary counter with 4 JK-Flip Flops, and they're inverted at the start as you can see.

http://vvcap.net/db/gR-BVk0KYT9jQ1cZsG06.htp

Here is the whole circuit.

http://vvcap.net/db/PBXZ0e2u_mXxmNGvOrP4.htp

This is the one I'm not sure of, how am I supposed to make those "switches" with 0 and 1.

http://vvcap.net/db/GO9_7FQ6F_5X8wMZclo-.htp

2. ### Wendy Moderator

Mar 24, 2008
20,772
2,540
It looks OK to me. I'm not sure what the question is. Generally it is assumed (and you have the set/reset lines wired to make it so) that a counter starts on 0000.

These flip flops toggle on the negative edge, so as the previous number goes to zero the next digit goes to a one.

I used to bread board those circuits for fun when I started out, over 40 <mumble> years ago.

Transon likes this.
3. ### vini_i New Member

Apr 19, 2010
14
1
some flip flops have a set and reset built into them. the two switches that you mention are to set (store a one) or reset (store a zero) in the flip flop regardless of what is at the input.

when a flip flop first powers up the state that is stored in it is unpredictable. it can be a zero or one. so the set and reset functions are used to change the state of all the flip flops to a particular value so that everything else is predictable.

this is generally invoked by some device that can sense a power up condition and change the state of all the flip flops to a set state.

or in this case to reset the counter to either all zeros or all ones.