a day ago •
Here is another XOR circuit that I wired and tested last night. Thanks to Yann Guidon for this idea as it does further reduce the parts count. The Input resistors are optional depending on the logic level voltage. For a XNOR, just reverse the +5 and ground. This XOR, once again, has good solid logic levels on the output.
5 days ago •
I now have, thanks to @Starhawk for the nudge, managed to create A XOR and XNOR gate that uses just a single Light Logic switch. I no longer need to combine other gates for these logic functions. Logic highs are 4 volts or higher and the low levels are less than 0.5 Volts. Good enough to be used with the rest of the Light Logic family.
06/22/2019 at 22:24 •
I am working on a educational display to showcase Light Logic and how it works.
This is a combination of NAND, OR and AND gates to create a working XOR gate. And as the same for all Light Logic gates, transistors are not to be found. Just diodes and resistors. Power leads are under the paper to better show the logic wiring.
05/31/2019 at 23:29 •
I have worked out the circuits for the following gates. AND, NAND, Buffer, NOT, OR and NOR. With these I can make XOR and XNOR gates as well. These gates have good fan-in and fan-out capability.
05/28/2019 at 15:21 •
Light Logic now has a working 2 Input AND Gate as well as the initial NAND.
This gate still uses a LED and CdS photo cell at its core and two other resistors. The best part of this simple DRL gate is that, as with the NAND, its logic out level is refreshed where as traditional diode resistor AND gates are not. I will continue to adjust the resistor values for best performance but this gate works well as is.
05/26/2019 at 23:35 •
Here it is May 26, 2019 and want to present a brief video history of Light Logic and a working full adder using Nand DRL gates.
The basic Nand full adder circuit used for this project.
Laying out the gates.
Wiring the first XOR.
Wiring the entire adder. My wiring was very messy on this project.
First test was setting A In to one. Note the glow of the gates as they are active or inactive. Sum Out indicates a one.
Now A In and B In are set to one. Sum is zero and Carry Out is one.
A In, B In and Carry In are one and Sum along with Carry Out are one.
This is a great educational tool to visually see the actions of the gates while functioning.
12/14/2018 at 11:17 •
I had to add this to my very basic work area so I can better understand what is going on with my light gates. This Tektronix 2230 scope is just what the doctor ordered.
I have quickly discovered that my astable clock signal for IO is in need for some improvement. Not very square is it...
11/18/2018 at 18:07 •
This test project will be a Johnson Counter with 7 segment hex display.
First flip-flop wired, seven more to finish.
Rough layout of the gates. Top two rows are the flip-flops. The bottom two rows are the decode and invert logic.
The circuit on Logisim and provided by @matseng
11/15/2018 at 23:17 •
November 15, 2018 - just messing around with Light Logic tonight and wired up the same clock pulser circuit that I had used in the first few weeks of the IO Cardboard Computer project. This time all Light Logic gates from the clock itself through to the final output led.
Fed the clock output through three Not gates and then to one input of a And gate ( Nand + Not ) and then fed the clock directly to the other And gate input. Connected a led to the And gate output and the result was a very short pulse just like I had using DTL gates a year or so ago.
Just proves more and more what the Light Logic gates can do in real applications.
11/09/2018 at 01:48 •
It is possible. @matseng forwarded an idea to me that does latch on and off every time. The led is a standard bright white and the CdS cell is a large 1 inch dia. cell hacked from some old 1960's equipment. Cell resistance in total dark is over 100k Ohms and when lighted comes down to less than 100 Ohms. Also big thank you's to @Yann Guidon / YGDES and @Morning.Star for bringing ideas to make this all work as a package.
View under the hood. The real business end. Yes, two led's and Ldr's in there.
Here is the first video of the led latch in action.