Introduction: TOD: Diode Matrix ROM Intro (7-segment Display)
Tons
Of
Diodes
A new series of instructables that will be using tons and tons of diodes. No IC's are aloud, the only semi conductors are diodes and transistors. The only passive components aloud are capacitors, resistors, switches, inductors, and potentiometers (variable resistors for those who don't know). Another rule is it must have more diodes then any other component. I made this all up, and I made up this group to see how creative people can be with electronics without resorting to IC's. My next one (this one is just a little wimpy intro) might use up to 2000 diodes.
This is an intro to Diode Matrix Roms, basically it takes a signal in (switch) and gives an output (number on the display)
NOTE: I couldn't complete a project designed by myself because my breadboard is way too small, but That'll be fixed in later instructables.
Step 1: Parts
7x 68 ohm resistor or higher (I used somewhere 110 I think)
1x 7-segment display
1x 10dip switch (I could only find an 8, just less characters to display)
23x signal diodes (cheapest you can find), I had 23, but I could only fit 9 on my board
1x breadboard, preferably big (unlike mine)
Some jumper wire
some sort of power supply, like 2AA or AAA's
wire cutters help
Step 2: Put the 2 Main Components on the Board
insert the display and the dip switch (heheh dip switch) on the center of the board, ontop of the notch.
Step 3: Ground It
ground all of one side of the dip switch and ground the 2 ground pins of the display
Step 4: Save the LEDs!
Insert 7 resistors, one for each led and attach all of them to you power supply.
I later shortened the resistor leads to reduce clutter.
Step 5: Hook Up All the Diodes
Can't really help you here, just make sure they are all facing the right way and the leads arn't shorting out (especially the resistors, which could fry your display)
Step 6: Test It!
I could only fit so many diodes on my breadboard, so I could only make 5 numbers (well 6 if you include the default 8), only half that I could of done.
Congrats, you just made a Diode Matrix ROM
don't stop here, you could make lots of cool circuits. Later I'm going to make a big cube of weaving wire, with diodes connecting the weaving at certain spots driving an LED matrix.
Step 7: Schematc
here's the schematic I forgot to put in, sorry!
Edit: New, better setup by Fernbot
just put all of the diodes in the corresponding places. The diodes in the 2nd schematic (fernbot's) are just an example and have no particular output, it just is an example. Fernbot's schematic consumes less power, yet uses the same amount of components, just rearranged.
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49 Comments
14 years ago on Introduction
Holy power consumption!
As it stands now, your circuit consumes more power when the LEDs are off than when they are on*. Looking at your schematic, what if you pushed the LEDs to the top (next to the resistors) and then disconnected the cathodes of the LEDs from ground? You could then use your diodes to ground the cathodes of the LEDs. Since the LED + diode is a larger voltage drop, you'll probably have to reduce the size of the resistors to keep the same LED brightness.
It's fun to work with the basic components, isn't it? =D
*Your diodes turn the LEDs off because they have a smaller voltage drop (~0.7v) than the LEDs (~1.3v), right? This creates a larger voltage drop across the resistor when the LED is off, which leads to a larger current, and therefore higher power consumption.
Reply 8 years ago on Introduction
i know they should just have a normal off switch lol
Reply 14 years ago on Introduction
you are right! I'm glad you pointed this out! I don't get exactly what you're describing, could you make a schematic?
Reply 14 years ago on Introduction
btw it is fun to work with basic components ;)
Reply 12 years ago on Introduction
So true :). I just got done designing an ALU that can add, subtract, do all of the boolean logic operations, and now I'm working on bit-shifting. Once the design is done I'm going to hard-wire it all up.
-Y
Reply 14 years ago on Introduction
Ok, here is what I was thinking. Notice that now you put the diodes where you want the LED to be on instead of off. I just randomly put my diodes in the schematic, so the output would probably be meaningless, but hopefully it gives you the idea.
Reply 14 years ago on Introduction
ohhhhh so the switches are normally on, but when you flick the switch off so do the leds.. I'm going to post that schematic as a better way of doing it on my instructable
Reply 14 years ago on Introduction
you make a good point, I'll check with my multimeter, be back in a jiffy!
9 years ago on Step 7
thank you very mach
9 years ago on Introduction
what you're doing with these instructables, is just awesome :)
10 years ago on Introduction
May I have a layout for printed circuit board?
12 years ago on Introduction
sry 9 bits
12 years ago on Introduction
plz i need help.......how can i connect (9 digits)binary to seven segment? without decoder (9 -512)??????????plzzzzzzzzzzzzzzz help meeeee.thnx
12 years ago on Introduction
Okay, correct me if I'm wrong, but with diodes it's possible to make non-volatile (won't lose it when the power goes off completely) memory cells? Right?
This is just what I need for my project. At first I thought about capacitors, but deemed it way too complicated. Also, where would I find a tutorial on doing this?
(By the way, I love what you're doing with these instructables, and I hope you keep going. I prefer transistors to diodes, but still awesome).
-Y
14 years ago on Introduction
There's a PDF about DEC logic modules used in PDP computers. It's full of information about using DTL to make stuff, including adders, etc. The link is here
I made a 2 bit plus carry adder out of DTL a few months ago, but I can't find any pictures of it. There were about 15 transistors and 28 diodes.
Reply 14 years ago on Introduction
thanks for the link! I'll look at it once it's done downloading (25 MB!)
I'm making a 2 digit adder (xx + xx = xxx) only from diodes
the schematic is a pain in the butt.
Reply 14 years ago on Introduction
I been working on DTL aswell. I have figured out every gate I could find info about. NOT, OR, AND, NOR, NAND, XOR, XNOR. Are there any that I have missed? When I have got a full set I'm goin to make an instructable on it.
Reply 12 years ago on Introduction
Nope. That's all of 'em.
13 years ago on Introduction
Perplexing question!
Hello
Dr. asked me a question related to the university b Markp ROM on the design of the type of ROM through the Diode Matrix
Q) Design an adoide matrix read only memory that stor the following 20 words:
1-10111101
2-00101011
3-10111100
4-01000011
5-11101000
6-10011001
7-10111011
8-01100111
9-11101001
10-10111101
11-10000110
12-00010111
13-11001100
14-11111000
15-11001101
16-11000001
17-11001111
18-01100110
19-00101011
20-11111111
How to answer it and drawing with diode matrix read only memory??!!
13 years ago on Introduction
Is there a way to make this circuit to have a +5v input at each point instead of the switch? In other words input a +5 volt signal at any point and display the corresponding number on an LED 7 segment display. This would tell you which one has the +5v signal at its input.