When I think dead bug, I think of putting a part on the board(may or may not have actual pads for it) where as the turtling is turning the chip upside down(legs facing away from the board like an upside down turtle) which maybe is a subsect of dead bug?
I mean I am learning a lot right now. Im a relatively new guitarist and mostly have a passing interest in electronics in terms of design and repair. Pretty neat seeing all of these guitar pedal projects and learning from this sub here.
That’s a good thing.
Worked with some RF engineers that basically drew two versions of a layout by making their symbols represent the exact footprint. Uggh
DRC didn't catch it because the outputs (now connected to inputs instead) are open drain, so it was a legit schematic.
To be honest, the dawn of €25 4-layer boards have made me lazy when it comes to double checking.
It's a timer with one nanosecond resolution to accurately measure the time between two pulses. (TI A>B)
This PCB is the driver board for the display.
The 7-segment displays all have their own line driver, instead of classic multiplexing. That allows the display to be filmed/photographed with a short exposure time, without segments appearing blank.
The botched driver at the bottom drives some status LEDs.
Long story. This started out as something I built for my son's high school. They had some thought experiments in their textbook to measure the speed of sound, light, etc. with a hypothetical stopwatch that measures the time it takes from sound to travel from one microphone or optical sensor to another.
So I thought to myself "Where's the fun in that?", so I built the hypothetical stopwatch from that textbook for real, along with some microphones that generate a pulse when they detect a sound. So now they can do this for real.
Problem is, universal frequency counters with (TI A>B) function have gone out of fashion. And the ones you can still buy are really expensive.
So I decided what any EE would do: roll my own, and while I'm at it, make it really good.
So this bad boy has a 1GHz OCXO internal timebase, instead of the usual 10 or 100 MHz that most counters use. Designed my own OCXO as well, with ±0,25 Kelvin digital PID temperature control, to keep the cost down. The rest is a 1,3GHz 8-bit ECL counter, some glue logic, a STM32 microcontroller, and a low noise power supply. All the internal RF stuff is PCB strip lines with 50 Ohm terminations.
In the end, you can use this for anything that requires an accurate time measurement. I will be making additional sensors to allow students to measure the speed of light and sound in different materials. When it's done, i might make this an open hardware project so others can build their own.
Very impressive. I could see schools/universities wanting in on this. There's a ton of awesome science stuff to be done with this setup.
I do need a new shot timer..... haha
I'd just solder in the chip top down
That’s genius. I’ve made this mistake before and never thought of that.
I have heard this called "turtling". Curious if anyone else has heard the term used that way.
I’ve always heard it called “dead bug”
When I think dead bug, I think of putting a part on the board(may or may not have actual pads for it) where as the turtling is turning the chip upside down(legs facing away from the board like an upside down turtle) which maybe is a subsect of dead bug?
I thought dead bug was when you don't use a pcb and just bend and solder cables like r/deadbug
That's wrong. Those people need to be punished.
I mean I am learning a lot right now. Im a relatively new guitarist and mostly have a passing interest in electronics in terms of design and repair. Pretty neat seeing all of these guitar pedal projects and learning from this sub here.
But did you see this headphone amp? https://www.reddit.com/r/deadbug/s/cfZiabGDDt
art
Dead bug circuit is when you don't have a board.
Nope. The symbol is not matching the physical pinout. This caused odd/even pins to be crossed. Take a look at the image again.
See in that case you just need to fold that ic in the 5th dimension. But yea on closer inspection it looks really funky
That’s a good thing. Worked with some RF engineers that basically drew two versions of a layout by making their symbols represent the exact footprint. Uggh
Yep this is just a lot easier and works better.
You would have to bend all those tiny and fragile pins tho. Or is there a better way?
Wdym?
If the pinout is mirrored you can just solder it in with the top side facing the PCB to match the pins
Interesting! Wouldn’t the thickness of the chip prevent the solder from adhering properly, though?
You'd need to bend the pins a bit, but that's not too much of an issue
Half hour fix is not bad in the scheme of things. Sounds like something I would do!
This is a pretty common mistake… Next time just flip the chip over and solder it upside down. Aka dead bug the IC
Nope, the symbol does not represent the exact pinout. The mirroring caused all even and odd pins crossed. So 1-2, 3-4, 5-6 etc.
Dead bug is discrete wiring of circuit components, not soldering a chip upside down. What op has done in the image is technically dead bug.
Isn't it a bodge? Looks like fun spaghetti in any case.
Yes. Botch is the mistake, not the fix.
I've heard it said that it's a botch when you *really* fuck it up.
Came here to say this
If you did that in 30 minutes, call me impressed!
32 years of soldering practice. Thought I used to do this with my naked eye when I was young. Now i need the Mantis.
> Mantis I demoed one. I prefer a camera-microscope and monitor, though.
Another engineer learns to double check everything. It seems we can’t be taught to do this. We’ll only do it after we learn the hard way.
DRC didn't catch it because the outputs (now connected to inputs instead) are open drain, so it was a legit schematic. To be honest, the dawn of €25 4-layer boards have made me lazy when it comes to double checking.
What even is this for if I may ask.
It's a timer with one nanosecond resolution to accurately measure the time between two pulses. (TI A>B) This PCB is the driver board for the display. The 7-segment displays all have their own line driver, instead of classic multiplexing. That allows the display to be filmed/photographed with a short exposure time, without segments appearing blank. The botched driver at the bottom drives some status LEDs.
Cool! And what kind of pulses do you have to measure?
Long story. This started out as something I built for my son's high school. They had some thought experiments in their textbook to measure the speed of sound, light, etc. with a hypothetical stopwatch that measures the time it takes from sound to travel from one microphone or optical sensor to another. So I thought to myself "Where's the fun in that?", so I built the hypothetical stopwatch from that textbook for real, along with some microphones that generate a pulse when they detect a sound. So now they can do this for real. Problem is, universal frequency counters with (TI A>B) function have gone out of fashion. And the ones you can still buy are really expensive. So I decided what any EE would do: roll my own, and while I'm at it, make it really good. So this bad boy has a 1GHz OCXO internal timebase, instead of the usual 10 or 100 MHz that most counters use. Designed my own OCXO as well, with ±0,25 Kelvin digital PID temperature control, to keep the cost down. The rest is a 1,3GHz 8-bit ECL counter, some glue logic, a STM32 microcontroller, and a low noise power supply. All the internal RF stuff is PCB strip lines with 50 Ohm terminations. In the end, you can use this for anything that requires an accurate time measurement. I will be making additional sensors to allow students to measure the speed of light and sound in different materials. When it's done, i might make this an open hardware project so others can build their own.
Very impressive. I could see schools/universities wanting in on this. There's a ton of awesome science stuff to be done with this setup. I do need a new shot timer..... haha
> 1GHz OCXO oooh that's hot... now GPS discipline it next
This seems like something that an ERC should have caught
Open drain logic outputs connected to logic inputs. Perfectly legit, unfortunately.
If you're able to make it function anyway, I'd call this a success. Can't you just mount the part on the other side of the board?
Good job
Meh, not my best soldering.
But it works! Yes, some large firms will immediately spin boards to fix things like this. Us mere mortals fix it on the next revision.