Hexadecimal Relay Calculator

This is my hexadecimal relay calculator made using only relays, diodes and capacitors (with two resistors for the LED display).
Here's the final parts count:
122 Relays
159 Diodes
22 Capacitors
Sure, it's not the best calculator out there, but it was a ton of fun building it!

[@frankowalker4662]

What a work of art.

[@UsagiElectric]

Thank you so much!
The big back plane was a seriously long cut, but I think it made this thing look properly good!

[@RelayComputer]

I made one that can also multiply and divide. Only shows binary though. You are inspirational, man. Subscriber of this channel since long ago!

[@Dr_Mario2007]

Epic relay switch calculator, as it's kinda a replication of the earliest known digital computers predating the vacuum tube version.

[@ericchin739]

Ummmm no, these are electromechanical relays which were introduced AFTER vacuum tubes.
There wouldn't be relays without vacuum tubes.

[@jasons8479]

I'm happy to see calculators have come a long way since the boring silent pocket calculators of the 1980s. Everybody who's somebody should have one of these machines loaded with glorious clicking relays on their desk!
An absolutely beautiful feast for the eyes and ears indeed.

[@emilyhallfelder4264]

Sweet! I’d love to see you add a clear function tho lol

[@UsagiElectric]

Thanks! Yeah, that was a big oversight on my part, and I'm still not entirely sure why the subtraction requires a more complex clear. Unfortunately, without remaking the entire back plane, which was about 9 hours on the mill to make, it's going to be very hard to make a clear function. I may be able to squeeze something into the slots where the SRAM that has been eliminated is now sitting though, so I may look into that in the guture.

[@frankowalker4662]

@@UsagiElectric I realise I'm a bit late, but could you use a temporary push to break button inline with the power socket to make a reset switch ?

[@UsagiElectric]

@@frankowalker4662 That definitely could have worked, and probably would have been a better solution functionality wise than what I ended up using. However, that would have required recutting the backplane board, which was about a 9-hour cut on the mill, so I was doing everything in my power to avoid having to do that long of a cut again, haha.

[@frankowalker4662]

@@UsagiElectric 9 hours!!! No wonder you don't want to change the backplane. :)

[@ericchin739]

​@UsagiElectric
Use latching relays if you want to clear everything with one button press.
The reason subtraction is more complex in your setup is because of the "extra" carry bit from doing two's compliment.
You can solve that by using full adders instead of half adders.

[@neffk]

Interesting project. The un-labeled buttons are an unnecessary level of obfuscation, though. Still, it's a nice project and the presentation makes everything clear.

[@macksie1984]

What's it like having the best channel on TH-cam? I'm so sick of politics and have been watching a ton of your videos and Action Retro. Good stuff!

[@danaeckel5523]

Adrian's digital basement and LGR are great channels as well. Action Retro is pretty cool, I have been inspired by some of Sean's projects and I had to install NetBSD 9.2 on a Quadra 800 and install CircleMud.

[@mohamedb5060]

good job

[@UsagiElectric]

Thanks!

[@olivetta6417]

I'm trying to create a calculator, from scratch, with only simple parts (relay, diode, etc.). But I got to a chronic problem, how the hell do I convert binary numbers, ex:00101110 to decimal? so that I can make my display show 46 for example. Making the display translate a 0000...1001 (0...9) is easy, but what about after that? when a number comes with two or more decimal places (ex:10000000 =128). I know it can be tricky to explain, so is there somewhere I can find the answer, maybe a schematic?

[@thomasfok123]

It is easier to use Binary-coded Decimal (BCD).

[@malloryworlton6359]

It requires complex arithmetic. As Thomas Fok said, it will be much easier to use BCD, but it requires slightly different adder and subtractor circuitry.

[@olivetta6417]

@@malloryworlton6359 It's done. I used BCD

[@ericchin739]

You use a BCD encoder that goes to a 7-segment LED as he has here.
It takes binary (or hex) inputs and outputs the correct pinout for a 7-segment display.

[@sporeball]

amazing work!
where did you get those nice candy-colored button caps?

[@UsagiElectric]

Thank you so much! They were just a random "pcb push-button" grab off of Amazon for super cheap.

[@ericchin739]

I see the mistake you made as it drove me crazy trying to figure it out on my own.
If you're only using half adders - you get weird carry bits sometimes.
So, use a half adder for the first two bits - then full adders for everything else.
It allows you to not have an extra carry bit showing in the answer.

[@postualin6551]

A schematic please ?

[@UsagiElectric]

Hi, thanks for checking the video out!
Unfortunately, I never really made a schematic for this one. I just kind of built it board by board and through blind luck it worked. You can see the PCB design for each board here though: postimg.cc/gallery/JJkFZNB
Also, I go into detail about what each board does here: th-cam.com/video/aJaDF2zCYNY/w-d-xo.html

[@postualin6551]

@@UsagiElectric thanks a lot for the information anyway