Can you help me convert my logic diagram to a breadboard?

[JKThomas96]

These are the 3  chips I have chosen, all belong to the 74xx series.



not 100% sure where to go from here but I have looked up the data sheets and understand what I need to do in theory, but actually in practice im finding it very difficult.

[neil t]

First, we cannot see the attachments from the other forum, unless we "sign in", so we won't be able to comment on the first part of your exercise.

I will just skip to the basics on breadboards....


This is a typical breadboard:


The connections inside are like this:


(Partial cutaway)


They are especially well suited to DIP ICs with 0.1" pin pitch and 0.3" spacing between rows of pins - where you would fit them like this:


You will notice there are two sets of rails - one pair at the top and another at the bottom.  They are often marked with coloured stripes - but not always.  The colour of the stripes means nothing - unless you choose to give them meaning.  The set of rails at the top is NOT internally connected to the set of rails at the bottom.  Also - for "full size" breadboards, the rails are often split in two (as the break in the coloured stripes indicate) - but again, not always.

Most component pins can fit in the holes - but big ones may not do so without stretching the contacts inside the breadboard.  Small ones may not get good contact - especially if the particular hole has had big leads put into it beforehand.

Interconnections are made using pieces of solid core insulated wire of a suitable gauge, where the ends have been stripped back by 5mm or so (telephone wire is good) or by using specifically manufactured jumper leads which have a moulded pin at each end.

just a quick heads up if your breadboard has broken red and blue power rails as in figure 1 don't forget to put jumpers across them otherwise half your breadboard won't have power, iv'e been caught out with this one a few times (easy to over look).

[Brumby]

Don't use the 74LS21.  It's a dual quad input AND.  While you can configure it to do the job at hand, it's a departure from the basic exercise.

Use the 74LS08 instead.

[alanb]

Google the pin out for the chips so that you can identify the pins that you need to connect. Start by identifying and connecting  ground and Vcc. These will be pin 7 = ground and pin 14 Vcc when looking at the chip with the notch at the top, pin1 is top left go anti clockwise round the chip pin7 bottom left, Pin14 top right. Its much easier if you look at the diagram.

[JKThomas96]

Don't use the 74LS21.  It's a dual quad input AND.  While you can configure it to do the job at hand, it's a departure from the basic exercise.

Use the 74LS08 instead.

Unfortunately I can't seem to find 74LS08 in Fritzing. I really have no idea what I'm doing here, I'm trying to understand it but I'm having real trouble. I don't even know what power source we are using as the lecturer is the only person allowed to use it. I don't even know where my resistors should go, where my inicial inputs should start from going in to the gates.

I'm honestly losing hope with this. I have a to have a breadboard diagram, as well as be able to lay out my circuit to be assessed in 15 hours. This counts for 40% of my year in one module and I'm clueless due to the amount of time I spent off.

If I can't get this working my only option is to ask the lecturer for an extension which is going to go down like a lead balloon.

[rstofer]

If you have to use a 4 input AND, tie two inputs together and to +5V  That will leave just 2 inputs for the logic inputs.
You will need to use another inverter on the output because the 74LS logic will not pull an LED up.  In other words, the logic one output is WIMPY.  You need to pull down when the logic is correct so just invert the output and let the inverter pull down.

Connect the anode of the LED to +5, tie the cathode to one end of a 470 ohm resistor and connect the other end of the resistor to the output of the added Inverter.

I don't know anything about Fritzing

One suggestion:  Put pin numbers on your sketch.

[SL4P]

rstofer, You're trying to explain ideas that are about a month ahead of the OP.

It sounds like he doesn't need an ACTUAL breadboard or chips.
Just a diagram of what he needs to layout on the board, and how the wires link it all up.

Much as i hate it, Fritzing was made for this.
Now all he needs to find is a 7408 library component.

OP, just assume the lecturer is going to provide a 5V supply

[Brumby]

OK - if you want to stick with the 74LS21, just join two of the four inputs together to make one input and do the same for the other two to make a second input.  For this exercise, that will work just fine.

If you have to use a 4 input AND, tie two inputs together and to +5V  That will leave just 2 inputs for the logic inputs.

... or you can do that.

As for the wiring of the ICs are concerned, just use these types of diagrams and it should be more obvious:

[Brumby]

Please understand that while we are more than happy to help you, we are not going to give you a solution.  We have also had people rock up here at the last minute and expect us to do their homework for them.  Not going to happen.

We want to give you the information where you can build your own solution.  That's how you will learn.

You will need to calm yourself and take in the pieces of information one-by-one, then put them together and we can critique and guide you further.

[IanB]

I'm honestly losing hope with this. I have a to have a breadboard diagram, as well as be able to lay out my circuit to be assessed in 15 hours. This counts for 40% of my year in one module and I'm clueless due to the amount of time I spent off.

You are panicking too much. Try to calm down a bit.

All you have to do is copy the circuit diagram you have onto the breadboard. Where the inputs and outputs are on the logic gates you will have pins on the ICs. Where the lines are on the diagram you will have patch wires on the board. In addition you will need to connect power to the VCC and GND pins on the ICs.

[Buriedcode]

Also, not sure if it was mentioned, you're using 7400 series devices.  The letters after the '74' indicate the technology used.  LS is very old and probably hard to find, so look for 74HCxx or 74HCTxx.

'HC' will work with ~3-5.5V, HCT is 4.5-5.5V, so 5V only. If you're using 5V, either will work and are far more accessible than the old LS series.

The 'xx' is the device type.  Because HC, HCT, LS F, ACT etc.. are basically the same devices, with the same pinout, CAD/schematic software will omit them, leaving you only with '7408' of example.

Exit: just noticed this was already covered!  Apologies to Ian.M.

[SL4P]

Also, not sure if it was mentioned, you're using 7400 series devices.  The letters after the '74' indicate the technology used.  LS is very old and probably hard to find, so look for 74HCxx or 74HCTxx.

For your requirements in this project, all the 74 families have the same DIP pin out.
The differences are in the silicon, voltage ranges etc.  No concern to you in this case.

[ez24]

I came across this site via this forum recently.  I think you are suppose to be able to simulate logic chips but I cannot get it working because of some setting in my Java but worth a look (I think). It may work for you.

https://tams.informatik.uni-hamburg.de/applets/hades/webdemos/gatelevel.html

You can find more by searching on "digital logic simulation"

[JKThomas96]

Thanks for all the comments, I got a bit wound up earlier from frustration but I've managed to settle down and produce something.

Here is what I have



The 74xx08 chip in the middle is a 74HC08 chip I imported from google, because I couldnt find it in Fritzing

Here is the pinout diagram for it just to be sure



Would be extremely greatful if somebody could take a look and let me know if I'm on the right tracks.

[SL4P]

I haven't traced through your logic, but the Fritzing looks good - you caught all the imprtant stuff (power, orientation etc).

One comment.  Don't call your links A B etc (like the LED at right) - as they are the same names as your inputs!

EDIT:

Connect the anode of the LED to +5, tie the cathode to one end of a 470 ohm resistor and connect the other end of the resistor to the output of the added Inverter.

Be careful - while this is the way we would probably do it, it introduces inverted logic - which may confuse the OP why his LEDs are 'upside down'.

[JKThomas96]

I haven't traced through your logic, but the Fritzing looks good - you caught all the imprtant stuff (power, orientation etc).

One comment.  Don't call your links A B etc (like the LED at right) - as they are the same names as your inputs!

Thanks for the reply, I did actually second guess myself for a second and adjusted it to this, as I thought the resistor needed to connect to the rest, but I'm glad you've said it is okay. Thanks for the tip on input naming too, makes sense.

[Buriedcode]

One thing, your green LED doesn't appear to have a ground connection.  Whilst I'm sure you know it requires one.. for completeness!

[IanB]

Naming your inputs A, B, C was fine. Except the A upper left was the same as the A lower right. So instead of duplicating it you should use a link wire to tie the one input to both places on the breadboard.

Also remember that you can only plug one wire into one hole, so don't try to plug two (or three!) wires into the same one.

Finally, putting labels like A' AND B on the drawing was a good idea. Keep those labels.

[JKThomas96]

Naming your inputs A, B, C was fine. Except the A upper left was the same as the A lower right. So instead of duplicating it you should use a link wire to tie the one input to both places on the breadboard.

Also remember that you can only plug one wire into one hole, so don't try to plug two (or three!) wires into the same one.

Finally, putting labels like A' AND B on the drawing was a good idea. Keep those labels.

Thanks for the tips. Just to ask, am I able to put a wire in the same hole as a resistor? If not should I put the wire below the hole the resistor goes in to?

Definitely keeping the labels, helped me out big time in understanding what was exactly happening.

[MK14]

Naming your inputs A, B, C was fine. Except the A upper left was the same as the A lower right. So instead of duplicating it you should use a link wire to tie the one input to both places on the breadboard.

Also remember that you can only plug one wire into one hole, so don't try to plug two (or three!) wires into the same one.

Finally, putting labels like A' AND B on the drawing was a good idea. Keep those labels.

Thanks for the tips. Just to ask, am I able to put a wire in the same hole as a resistor? If not should I put the wire below the hole the resistor goes in to?

Definitely keeping the labels, helped me out big time in understanding what was exactly happening.

Definitely ONLY one lead or wire per hole. NEVER more than one.

[JKThomas96]

Naming your inputs A, B, C was fine. Except the A upper left was the same as the A lower right. So instead of duplicating it you should use a link wire to tie the one input to both places on the breadboard.

Also remember that you can only plug one wire into one hole, so don't try to plug two (or three!) wires into the same one.

Finally, putting labels like A' AND B on the drawing was a good idea. Keep those labels.

Thanks for the tips. Just to ask, am I able to put a wire in the same hole as a resistor? If not should I put the wire below the hole the resistor goes in to?

Definitely keeping the labels, helped me out big time in understanding what was exactly happening.

Definitely ONLY one lead or wire per hole. NEVER more than one.

Thank you, so below the resistor hole or to the side?

[MK14]

Thank you, so below the resistor hole or to the side?

Where the lines are (from this image "stolen" from earlier in this thread).
I.e. Each contiguous black line, means they are wired/shorted together.
So for each black "strip" of (e.g. 5) holes, all leads/wires/components connect together, if plugged in to it.
The black lines are isolated from each other.

[JKThomas96]

Thank you, so below the resistor hole or to the side?

Where the lines are (from this image "stolen" from earlier in this thread).
I.e. Each contiguous black line, means they are wired/shorted together.

Thought a smuch but after a day filled with errors I wasn't taking any chances.

Thank you all, really couldn't have done this without you all 

[MK14]

You're welcome!

Also, I bet after you have done all this, you will be amazed at how easy it was!

Good luck!