Reddit:Electronics

[group 4b][variant 4b] 0x0_ = MISC Opcode Name Description

0x00	NOP	No operation
0x01	HLT	Halt CPU execution
0x02	INT	Trigger software interrupt
0x03	CLC	Clear carry flag
0x04	SEC	Set carry flag
0x05	CLI	Clear interrupt enable flag (disable interrupts)
0x06	STI	Set interrupt enable flag (enable interrupts)

0x1_ = MOV Opcode Operands Description

0x10	reg, reg	Copy value from register to register
0x11	reg, [mem]	Load value from memory address into register
0x12	[mem], reg	Store register value to memory address
0x13	reg, #imm	Load immediate value into register
0x14	[mem], [mem]	Copy value from memory address to memory address
0x15	[mem], #imm	Store immediate value to memory address
0x16	reg, [reg]	Load value from address held in register (pointer read)
0x17	[reg], reg	Store register value to address held in register (pointer write)

0x2_ = ALU Opcode Name Description

0x20	ADD	Add register to accumulator
0x21	ADC	Add register to accumulator with carry
0x22	SUB	Subtract register from accumulator
0x23	SBB	Subtract register from accumulator with borrow
0x24	AND	Bitwise AND with accumulator
0x25	OR	Bitwise OR with accumulator
0x26	XOR	Bitwise XOR with accumulator
0x27	NOT	Bitwise NOT of accumulator
0x28	CMP	Compare (subtract without storing result, sets flags only)
0x29	INC	Increment register by 1
0x2A	DEC	Decrement register by 1
0x2B	SHL	Shift left, MSB goes to carry, LSB set to 0
0x2C	SHR	Shift right, LSB goes to carry, MSB set to 0
0x2D	ROL	Rotate left through carry, MSB goes to carry, carry goes to LSB
0x2E	ROR	Rotate right through carry, LSB goes to carry, carry goes to MSB

0x3_ = JUMP Opcode Name Description

0x30	JMP	Unconditional jump to address
0x31	JZ	Jump if zero flag set
0x32	JNZ	Jump if zero flag clear
0x33	JC	Jump if carry flag set
0x34	JNC	Jump if carry flag clear
0x35	JS	Jump if sign flag set (result negative)
0x36	JO	Jump if overflow flag set

0x4_ = STACK/CALL Opcode Name Description

0x40	PUSH	Push register onto stack, decrement SP
0x41	POP	Pop value from stack into register, increment SP
0x42	CALL	Push PC onto stack, jump to address
0x43	RET	Pop PC from stack, return to caller
0x44	IRET	Pop PC and flags from stack, return from interrupt handler

Github repo with all docs and files: https://github.com/mrFavoslav/8bit-cpu-MESAx8
The 8-bit ALU might not work perfectly at the moment. I recently moved some parts of the design around, so there's a good chance a few wires got messed up or misaligned in the process. Any feedback or bug catching is highly appreciated!

I'll be posting my progress here and on https://www.favoslav.cz/blog/

Finally! I made a perfect pcb on a CNC with a UV mask 🔋. I really love how the copper looks under the mask.

This is a portable lab device help to do experiment like diodes bjt amplifier gain and act as a function generator

On the bottom left it is shown next to its accompanying vacuum tube power supply, not a single semiconductor used in the whole setup. Wiring is horrible, and its performance reflects that. But at least it looks nice. Uses a 2" diameter 902 CRT, and is based mostly on a 1945 RCA schematic for this tube.

The CRT only runs at <600V (schematic specifies 577V, mine only runs on ~400V), which is remarkably low for a CRT but it definitely still hurts. Uses two 6SJ7 pentodes for vertical and horizontal amplification with a Type 884 thyratron for sawtooth generation. Has x-y mode and internal/line/external sync. Rectification is done with a Type 80 for B+ and a 6AU4 for the negative CRT supply (grounded anode).

The tube could maybe use some magnetic shielding and I am trying to figure that out, but for now I just keep the power supply away from it to eliminate the interference. Whole thing uses a little over 60W when running and is fused accordingly.

This is by far my highest-effort electronics project ever, and I am very glad to be done with it! I started this project over a year ago before, I got my real oscilloscope. Whadaya think?

It wasn't working, so unplugged it and the metal was hot as hell. So took it apart, soldered some leads for power and gave it some juice. Got a lot hotter than I was expecting. Resistor was reading as .5Ω

I’m a graduate electrical engineer with over 12 years of experience in electronics. I’ve worked on a wide range of projects, and I thought I had seen most things by now… but I’ve never seen capacitors that look like this.

Macro shot taken using Fujifilm XH2 and Laowa 65mm F2.8.

Captured using Fujifilm XH2 and Laowa 65mm F2.8.

UV module taken from a Convoy S21A light

I added RGB backlighting to my RAM stick to get +20 fps.

This is a heart-shaped LED keychain I made.

My attempt at making a really minimal switching LED driver (as lean as possible without "abusing" components), for a flashlight or something.

I had a lot of fun optimizing it without abusing strange nonlinear effects in components - I would guess the minimum parts you'd need are a choke, (obviously) an LED, sense resistor, flyback diode and 2 transistors (minimum required to create hysteresis).

If you were going to use it with 12 volts of Vdd, the component values would be about 470 uH, 10 ohm shunt, 1k pull up resistor, 10k pot, and a feedback resistor in the tens of kohm, this should yield an LED current of a couple hundred milliamps.

Let me know if you can remove any more components, or if you find it useful somewhere!

This is a laser I’ve made for milled blank double sided boards with mounting holes for alignment. Previously it’s worked for single sided pcb & now I’ve ben working on making a easy system for double sided & still working on a different homing system for easier flipping of the board. The etching fluid I use hydrogen peroxide with hcl. Main board ESP32, gcode sender I use is laser GRBL , where I just insert a screenshot of my traces and resize based on the dimensions of the blank. It’s generally very easy the most challenging part is still aligning, each board takes about 1hr from blank to etched with no drilling & 80% of time is on waiting.

Project files:
https://grabcad.com/library/pcb-laser-v2-1

I’d appreciate a like if anyone uses GrabCAD, it helps my career :) , any feedback or ideas here are also very appreciated!
Still working on V3 with its own firmware for aligning and faster motion, I will likely be done with that in a few months if anyone is interested! I’ll make a update. If anyone decides to make this machine buy a cover for fumes and light protection!

Captured using Fujifilm XH2 and Laowa 65mm F2.8. Quite the beauty.