Please help me out with this circuit

[mocuZ]

Hi, I'm a newbie here.
Here's my problem: Yesterday I found this circuit (control.pdf).
The question that bothers me is: how is this working?
When I push a button a LED goes on, but what happnes when I randomly
push a second button? Does the first LED go off or continues to light?

I'm confused. Please help me.

 

[ericgibbs]

Hi, I'm a newbie here.
Here's my problem: Yesterday I found this circuit (control.pdf).
The question that bothers me is: how is this working?
When I push a button a LED goes on, but what happnes when I randomly
push a second button? Does the first LED go off or continues to light?

I'm confused. Please help me.

hi,

It goes off.

EDIT: explanation.
The 374 is an 8 stage 'D' type flip flop.
Pushing any button generates a 'clock' pulse.
The pushed button line sets the input for that button 'high' so a 'high' is latched on the corresponding output of the 374 by the clock.
When the button is released the input line goes 'low', so pushing any other button will generate a clock which will now set the old output 'low'... The new output will be high.

Whats is supposed to be used for.??

 

[mocuZ]

Hey, thanks a lot, ericgibbs!
This I will use as a control circuit for a switch that I've designed. The switch has ... 16
different states. So I needed a control that could let me set each of the 16 states with
a simple click of a button. After a week of reading theory and searchin' in Google
yesterday I found THE CIRCUIT and of course I wasn't sure what I've found. I thought
of an explonation that was like yours and ... at the end of the day I just gave up.
Until today.

 

[ericgibbs]

Hey, thanks a lot, ericgibbs!
This I will use as a control circuit for a switch that I've designed. The switch has ... 16
different states. So I needed a control that could let me set each of the 16 states with
a simple click of a button. After a week of reading theory and searchin' in Google
yesterday I found THE CIRCUIT and of course I wasn't sure what I've found. I thought
of an explonation that was like yours and ... at the end of the day I just gave up.
Until today.

Hi,
That circuit could be modified as follows.

Replace the push buttons with normally open toggle switches.
Drop the NOR and NAND gates.
Have a single push button, when pressed generates a clock.
Each LED would have its own series resistor.

Action: set up the switch pattern on the toggles, then press the clock push button, this would latch the toggle switch states on the 374 output.

Tell us what you are trying to control.?

 

[mocuZ]

I'm controlling 4-port Keyboard/Mouse switch.
And the user wants to control which KM couple goes where.

 

[MrAl]

Hi,


I see a 'few' problems with that circuit.

First, the NOR and NAND gates need to be swapped, and an
inverter added to the CLK line of the LS374.
Second, the inputs or outputs of the LS374 all need to be
inverted, or reverse polarity of the LEDs and run R9 to Vcc.
Third, R10 removed.

Because of all these problems, i like Eric's idea about using
8 switches for the data lines, and one extra switch for the
clock line. This way you can clock in the switch data
with one switch and eliminate all the logic gates.
The only other change then would be to wire the
resistor R9 to Vcc instead of ground, and reverse the
polarity of all the LEDs.
Doing this, when you press a switch and then press and release
the clock switch the LED of choice would come on and stay on.

To recap:
Remove all the logic gates (LS27, LS10).
Wire in another switch to pin 11 of the LS374, but have its
resistor go to ground and have the switch go to Vcc.
Reverse all the LEDs, run R9 up to Vcc instead of ground.

If you dont want to use the extra switch for the clock line,
then we'll have to revamp the way the gates are connected
(such as swap the LS10 and LS27 gates and other changes).
Let us know what you want to do.

 

[mocuZ]

I want to switch.
Here's an exmple:
1__ __1
2--\/--2
3--/\--3
4_/--\_4
I don't know whether this would help you understand me. I hope so.
The basic idea is that there's no empty line.

 

[mocuZ]

Hi, guys. It's me ... again.
I've got another problem - Control.pdf. Could you help me out, please.
I need to "unite" the tree schematics into one so that when i push a
random button only that button produces "high" logical level and all the
others are "low"; at the next step when i push another button the first one
goes off and the current pushed button goes on.
What I am trying to explain is the first schematic but with 24 buttons.

 

[ericgibbs]

Hi, guys. It's me ... again.
I've got another problem - Control.pdf. Could you help me out, please.
I need to "unite" the tree schematics into one so that when i push a
random button only that button produces "high" logical level and all the
others are "low"; at the next step when i push another button the first one
goes off and the current pushed button goes on.
What I am trying to explain is the first schematic but with 24 buttons.

hi,
Have you got access to commonly used ic's .?

Whats your location.?

 

[mocuZ]

Actually ... no.
My location: Bulgaria

 

[ericgibbs]

Actually ... no.
My location: Bulgaria

hi,
Can you get these ic's .
3 * 74LS374, 1 * 74LS30, 1 * 74LS32 also 24 * normally closed push switches.??
[resistors and capacitors]

A circuit could be made, which would light a single LED when a corresponding switch was pushed open.
The LED would remain ON, until another switch was pushed.

 

[mocuZ]

I'll try, but I doubt I'll find anything.
Meanwhile: can you help me "unite" the "24 button schematic"?

 

[ericgibbs]

I'll try, but I doubt I'll find anything.
Meanwhile: can you help me "unite" the "24 button schematic"?

hi,
I follow what you are saying about making 3 of the original circuits.

I see you have problems with the clock.

The way you described the original circuit in your first post is incorrect, now I have checked it thru.

If you look at the circuit each input to the 374 is held high by the pull up resistors
and when a switch is pressed that input is pulled low.
As all the other inputs are high their outputs will go high except for the one thats pressed, which will be low.
Its the opposite way round to your description.


Where did the circuit drawing come from.?

EDIT:
You could reverse all the LED's and feed the LED anodes from a resistor to +V.

So the low output would sink the LED current for the selected line.

 

[mocuZ]

Bad, bad.
Here's the original drawing: Electronic_sel_8.gif

Well then, can I just switch the "+" and "-" lines so that all the switches
come to a common "+" line. And the outputs would become with common "-".
One more thing: for my needs this schematic wan't drive LEDs at its
outputs; instead I will put buffers on each output and after the buffer a
number of analog switches (CMOS); maximum 4.
So with that control I'll drive the switches.

If there's anything else you want to know: ask me!

 

[eblc1388]

Obvious question.

What is a variable resistor trimmer doing in the clock line of a digital circuit?

 

[ericgibbs]

hi mocuz,
Look at this alternative circuit.

When a push switch is pressed the corresponding output pin of the 74LS374 goes low,having been clocked in by the 'delayed clock' the LED comes ON and stays ON when the switch is released.
ALL other LED's are OFF.

Pressing another switch turns the corresponding LED ON and the previous ON LED OFF.

 

[donwilly]

hi please ,i need to get a full circuit pics or schematic diagram of a remote wireless car ,can anyone please help me out

 

[ericgibbs]

hi please ,i need to get a full circuit pics or schematic diagram of a remote wireless car ,can anyone please help me out

hi,
It would be best if you started your own new thread.

 

[mocuZ]

Hi, ericgibbs,

Obvious question.

What is a variable resistor trimmer doing in the clock line of a digital circuit?

Sorry. No idea. I wandered that too. I tried getting in touch with the
original author and nothing came out.

I saw your idea and I like it. Thanks.
Tomorrow I'll draw it all: the tree button groups, the additional parts you've
added and see what will come out. When I'm done I'll show you what came
out as a whole picture.

What would you say about my offer to simply switch the "+" and "-" lines
of the schematic so that at the outputs goes positive impulse? Is it a bad
idea? Is this going to work at all? Or it's just nonsense? I am asking beacuse
the switches (MAX333ACPP) are positive triggerd, I think. I should have
mentioned that earlier. My bad.

 

[ericgibbs]

Hi, ericgibbs,

Sorry. No idea. I wandered that too. I tried getting in touch with the
original author and nothing came out.

I saw your idea and I like it. Thanks.
Tomorrow I'll draw it all: the tree button groups, the additional parts you've
added and see what will come out. When I'm done I'll show you what came
out as a whole picture.

What would you say about my offer to simply switch the "+" and "-" lines
of the schematic so that at the outputs goes positive impulse? Is it a bad
idea? Is this going to work at all? Or it's just nonsense? I am asking beacuse
the switches (MAX333ACPP) are positive triggerd, I think. I should have
mentioned that earlier. My bad.

hi,
Stop feeling BAD, it wont help you..
Always be positive, dont accentuate the negative.!

That variable resistor in the original circuit is so that you can delay the 374 clock edge.
The high going clock edge has to occur after a 374 data input pin goes high or low.

You could swop the highs/lows input if you wanted to, provided you altered other parts of the circuit to suit.

When you are ready post the final diagram.