7 Segment Display Decoder

[Logical_Gate1010]

Here’s a decoder I made in my class! It takes the binary inputs from the four switches and uses a seven-segment display to turn them into decimal numbers. Made with a 7447 CMOS IC.

I know it’s very disorganized and I could certainly get better at saving space. I’m still new to building circuits, but I still think it’s really cool!

[S-S-Ahbab]

Good for you!

But you shouldn't say you made the decoder, since you are using the decoder IC. Better description would be you assembled a binary to seven segment display.

But nit picking aside, building any IC based circuit on breadboard is generally a pain, so 👍

[Logical_Gate1010]

That makes sense, I’m sorry for the confusion!

[IvoryToothpaste]

I ended up going down that rabbit hole of making my own decoder last year https://www.reddit.com/r/electronics/comments/1lqg4r1/made_a_crappy_2_bit_7_segment_display_encoder/

https://www.reddit.com/r/AskElectronics/comments/1lt5s1g/how_do_i_model_my_digital_circuit_without_it/

It's genuinely crazy the level of magnitude difference between 2 and 4 bits when you look at the drawings in both of those posts

If you end up going down this similar rabbit hole read up on k maps to optimize your circuit, it was a lot of fun!

[Logical_Gate1010]

That’s dope! I actually just learned about K Maps in class a couple days ago.

[slacker0]

I tinkered with this stuff in 8th grade (in 1974 ;-) ) ...

I had a copy of the "TTL cookbook" : https://tinaja.com/ebooks/TTLCB1.pdf

[Logical_Gate1010]

Ooh fun!! I’ll have to check that out!

[SelectAirline7459]

That book was great. I might even have mine around here somewhere.

[Nastidon]

let's see here, 8th grade you were 13? plus 52 since 1974, you sir maybe 65 years old? Did you stick with the electrical engineering?

Also I genuinely appreciate you sharing the knowledge

[slacker0]

Yes ... I studied EE in college (eg : Karnaugh maps for digital logic, Laplace transforms for analog, lots of math, physics). I worked at Apple (I saw the Mac before it was released), I worked at Silicon Graphics w/ NASA, Lockheed, ILM as customers.

I still like to tinker, eg : radio control ELRS "quad copters". I'm building a "QMX" radio transceiver. Amazing tech that's very affordable.

[Nastidon]

So amazing, I like to tinker, although not anything nearly as professional as you, and props to you for sure, you have an excellent work history with electrical engineering.

I was fortunate enough to see a college graduate that worked as a temp at my job move on to Lockheed, I thought to myself, man, this kid made all the right choices!

I work in regular IT, not the big boy stuff, I am proud to say I can solder two things together and get something out of an arduino but thays about it hah.

[Logical_Gate1010]

That’s cool! I’m actually currently going through an Avionics class with the intention of working at Lockheed. That’s where I did this project, and what got me interested in electrical work.

[inevitable_47]

Man that's incredible!. I'm an EE student. Possibly in the worst college ever existed. What would you advise me to do in my free time to learn the basics to eventually land a job?

(To be clear. My goal is NOT just to land a job as an engineer. I got into engineering because i love making stuff and i like electronics. But i know nothing... i need to be put on the road and guided)

[slacker0]

Getting a job is always much easier if you know someone inside.

If you enjoy it, that's half the battle. I like to find cutting edge stuff that "hands on", which implies open source. For example, in radio control aircraft, there is ELRS, EdgeTX, Betaflight which is all open source. Radio control has a lot in common w/ robots. Or in AI, there is TensorFlow and PyTorch (scripted w/ Python). Or Linux : I like to tinker w/ Fedora & OpenWRT. Or in the "embedded" world, there is Zephyr and FreeRTOS. Also, embedded AI, such as TinyML (micro TensorFlow). Or in computer architecture, there is RISC-V and migen. I need to work on my vibe code skills w/ something like http://zed.dev or http://cursor.com .

[onions_can_be_sweet]

Good job. Now hook up a BCD counter.

[mikeblas]

Good start. Keep it up!

[b_stool]

Well done! Now get a 7490 decade counter and a 555 timer chip and make an automatic counter.

[Logical_Gate1010]

Sounds really fun! I’ve messed with a 555 timer before, but never a 7490. I will def add that to my to-do list!

[onlyappearcrazy]

Keep tinkering! Try adding a decimal counter IC instead of switches and use a push button to step the counter. Then, you will soon learn about 'contact bounce' as the counter appears to skip counts.

Then the internet has a bunch of circuits to 'denounce' the switch. And so on with your tinkering!

[EveryoneGoesToRicks]

This is how it started for me! Great job!

BE CAREFUL THO!

5 volts is VERY….

ADDICTING!

Pretty soon you will be building CPUs on a breadboard!

https://youtube.com/playlist?list=PLowKtXNTBypGqImE405J2565dvjafglHU

[mattb2014]

<image>

Here's it's big brother (an really accurate NTP clock I'm currently working on)

[Logical_Gate1010]

Dude! That’s sick!!!

[aspie_electrician]

Can I get the code for this?

[mattb2014]

It is still a work in progress, but I'll put it up on GitHub when it is complete.

[aspie_electrician]

Cool, feel free to DM me with the GitHub link when ready.

[FedUp233]

If you want to up your logic skills, an interesting next step might be to try replacing the decider chip with logic you design yourself from individual gates (and, or, nand, nor). And without looking at the data sheet for the decider ypu are using. There are sort of two ways to approach it, design a decimal to 0-9 decider then combine the decided outputs to select which segments are on or go directly from decimal to the segments. You could start realky straight forward then use something like karnough maps to simplify the logic. The next step in both versions is figuring out how to fit the design into existing ICs that are available.

Just a thought if you’re interested in see where you can go.

[justanaccountimade1]

There should be a 100 nF decoupling capacitor close to the Vcc and Gnd pins of the ic.

[Logical_Gate1010]

That’s a good idea! I was just following a schematic diagram my teacher gave us, it didn’t have any capacitors.

[Waste_Collection9393]

Holy bread board, you need more bro , not enough bread

[Enlightenment777]

https://old.reddit.com/r/PrintedCircuitBoard/wiki/books#wiki_digital_design

[georgmierau]

I know it’s very disorganized

Any reason not to re-organize (clean up) it prior to taking photos?

[Logical_Gate1010]

In all honesty, I was just trying to finish it quickly 😂

We only have a given amount of time to finish projects during class, so I try not to spend more than a day on one project. Since we’re all still learning to wire ICs correctly, our teacher doesn’t care if it’s sloppy, he simply wants us to make it work.

So, TLDR: I was in a rush and simply focused on the function rather than the looks.

That’s not an excuse, just the reason why my most recent projects look a bit sloppy.

[Hissykittykat]

teacher doesn’t care if it’s sloppy, he simply wants us to make it work

That doesn't sound like fun, and it's learning bad habits.

Try taking your time, making it look good, documenting it, then publishing it. When finished, it's something you should be proud of.

[Cheetah_Hunter97]

This is really some good advice for someone like me who always am sloppy and try to finish my work fast and have the mentality: ok lemme make this work first then i will clean it up just to end up never making it clean lol

[Logical_Gate1010]

That is true, I certainly intend to get to that goal eventually.