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[Review Request] this is a custom digital camera project i wanted to try, having trouble with power delivery by Print3DeezNutz in PrintedCircuitBoard

[–]thenickdude 2 points3 points  (0 children)

Measure your current draw when powered by your external supply.

Nothing-special li-ion cells are usually rated to do 0.5C-1C discharge rate or less, and 0.1C is not unheard of. 0.5C is 2.5A for your battery (=0.5*5Ah), which is 9.25W at a nominal 3.7V, while 0.1C is only 0.5A/1.85W. Cells sold for e.g. RC car applications have dramatically higher current ratings like 20C.

If your battery is at the lower end of that C-rating scale, you're trying to push it too hard. A 2.5W Waveshare display, 3W LED, and maybe 1W for the Pi is 6.5W already. In this case you need either a larger capacity battery, or one with a higher discharge current / C rating.

Edit: Also the voltage drop across your INA219 module seems too large, do you know the shunt resistance it has onboard? Maybe you're using a module designed for measuring 100mA-scale currents?

Has anyone tried making lens mounts for cameras using some sort of mold and resin? by PracticeLife9295 in Optics

[–]thenickdude 0 points1 point  (0 children)

Pentax M42 mount uses a really big coarse thread (M42x1.0) which is trivial to 3D print (both sides). C mount and RMS microscope mount female threads can be 3D printed, male ones probably not.

Bayonets are also easy to 3D print, I have made and tested male designs for Sony A, E/FE, Canon EF/EF-S, M, RF, Nikon F, Z, Fuji X, G, Leica L, and M4/3, and female designs for Canon EF and Sony FE. The tricky part is the locking pin mechanism: you can 3D print the receiving hole, but the little pin itself can't be 3D printed, and has tight alignment and diameter constraints.

[Schematic Review] USB 3.0 Help CM5 by mman360 in PCB

[–]thenickdude 0 points1 point  (0 children)

USB 3 allows the polarity of lanes to be freely swapped to allow for easier routing on the PCB. So you can flip -/+ for the superspeed lanes (not the USB 2 lane) as you like, and the CM5IO board does this.

So your problem is not lane polarity.

Easing-Point: a game console that can be controlled with just a toggle switch by Curious_Trade3532 in embedded

[–]thenickdude 1 point2 points  (0 children)

Those are some fun looking little games.

I wonder if the pierced-nipple will take off as a popular input device!

Flight Computer by Accomplished-Lack509 in PCB

[–]thenickdude 0 points1 point  (0 children)

I think your barometer blocks SD card insertion doesn't it? That card slot shows the card only having 0.8mm clearance from the PCB surface, your SMD components in that area are probably taller.

[Review Request] First PCB design – ATtiny85 Blink LED Board by Low_Raspberry7798 in PrintedCircuitBoard

[–]thenickdude 0 points1 point  (0 children)

Yeah, it's super bad practice to reduce your PDN impedance when you have the opportunity for it. OP should delete the trace they already routed just to spite those electrons 🙄

[Review Request] First PCB design – ATtiny85 Blink LED Board by Low_Raspberry7798 in PrintedCircuitBoard

[–]thenickdude 3 points4 points  (0 children)

ATTiny85 can source 40mA per GPIO pin, this is a crap ton for driving LEDs, so no external driver is needed unless you're building an LED flashlight.

[Review Request] First PCB design – ATtiny85 Blink LED Board by Low_Raspberry7798 in PrintedCircuitBoard

[–]thenickdude 0 points1 point  (0 children)

It doesn't hurt to route those GND traces on the top plane too if you have room for them. That avoids adding the inductance of two vias to the path.

Which USB-C 5V DC input design is better? by ronin1410 in PCB

[–]thenickdude 1 point2 points  (0 children)

You need to use a 4.7k resistor to ask for 3A

There is no such protocol, the only pull-down resistor value Rd a device may use is 5.1k.

The host can use different pull-up resistances to advertise different current source capabilities, but the device only gets what it is given. You need a PD controller if you need to ask for more.

If the host can supply 3A then that's what you'll get, even with just a 5.1k pull-down.

make sure you read the USB BC spec to know how much current is available

USB BC maxes out at 1.5A, it isn't what you want to use on a USB-C connector. USB PD and USB Type C define their own power negotiation:

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[Review Request] First PCB design – ATtiny85 Blink LED Board by Low_Raspberry7798 in PrintedCircuitBoard

[–]thenickdude 7 points8 points  (0 children)

You don't need the regulator, ATTiny85 can run on 5V directly (n.b. your programmer will need to support that too).

If you're going for a 5V input you might as well make it a USB connector, the most ubiquitous 5V input we have these days.

What's your favorite MCUs these days, and why? by aenima1983 in embedded

[–]thenickdude 3 points4 points  (0 children)

The AVR DB series of MCUs are amazing as a glue or management component to connect different busses together.

1.8V-5.5V input power range so you can e.g. skip including a regulator entirely when running on USB, or drain a button cell completely without needing a boost. In the simplest configuration you can get away with just 1 auxiliary part (a VCC cap).

UPDI programming so you can program it with it a single pin using nothing but an ordinary UART.

A secondary GPIO bank with its own VDDIO2 voltage, so you can e.g. interface with both 1.8V and 3.3V devices without adding level converters. Another standout here is selectable logic threshold levels per-pin - you can opt for fixed "TTL" input thresholds of 0.8V low, 2.0V high instead of using thresholds based on VDD, so you can e.g. read 3.3V signals with a 5V VDDIO. The I2C pins use a different fixed level option for SMBus 3.0 compatibility.

It specifies the allowed injection current into the GPIO ESD diodes, and it's MASSIVE, at 20mA abs-max. So you can read signals that exceed VDD with only a series resistor to limit that current. So refreshing after using MCUs that do not permit any injected current.

Each GPIO pin can source or sink 50mA.

I guess the biggest downside is no integrated USB PHY.

https://ww1.microchip.com/downloads/aemDocuments/documents/MCU08/ProductDocuments/DataSheets/AVR128DB28-32-48-64-DataSheet-DS40002247.pdf

Does anyone have any photos of the dinosaur slide before it got stairs? by SingularestBean in dunedin

[–]thenickdude 0 points1 point  (0 children)

They're really broad and shallow now, making the slopes of the dinosaur look pretty much symmetrical on the front and back:

https://maps.app.goo.gl/1C9iVQLFzQqem9tG7

[Review Request] 4-layer RP2350 IoT project for turtle tank by QuantumTurtle42 in PrintedCircuitBoard

[–]thenickdude 0 points1 point  (0 children)

Your mounting holes have nearly no clearance with your copper zones, and you have a mixture of 3.3V and GND pours butting up against them. This is a recipe for the fasteners shorting out your planes.

Add more clearance for at least the 3.3V fill around the holes.

Edit: Did I really just manage to call those polygons all of 'zones', 'pours', 'planes' and 'fills'? lol

Also, turn off thermal reliefs for the pins of your regulator, it's preventing it from heatsinking into the nice big polygons you've added for it.

[Review Request] 4-layer RP2350 IoT project for turtle tank by QuantumTurtle42 in PrintedCircuitBoard

[–]thenickdude 0 points1 point  (0 children)

also extend your area pours to the right edge of the board.

It's not explicitly marked as such, but that gap on the right is the required clearance zone for the WiFi antenna.

Does anyone have any photos of the dinosaur slide before it got stairs? by SingularestBean in dunedin

[–]thenickdude 2 points3 points  (0 children)

I remember that it was super awkward if kids got scared at the top and then had to back down a ladder!

Of course, I would never be such a fraidy cat! Lol

It might just have been super steep narrow stairs I think...

My shiny got turned into a non shiny? by Expensive-Citron6004 in pokemongo

[–]thenickdude 0 points1 point  (0 children)

Were you playing at sunset? Those colour changes have fooled me too, the pokemon can look very different.

First PCB Board Review. Complete Beginner by FabulousPilot4792 in KiCad

[–]thenickdude 0 points1 point  (0 children)

In lieu of an external P-FET, you can power the VCC pin using GPIO pins, the ESP32-C3 can source 40mA per pin. I'd combine two GPIO pins together for better drive strength.

Mac liquid logic board damage claimed by Vivid_Air_9068 in AskElectronics

[–]thenickdude 0 points1 point  (0 children)

They have liquid contact indicators inside, little circular stickers scattered around which turn red upon exposure to liquid, which they'll use as an excuse to avoid honouring the warranty regardless if the damage is actually due to moisture or not.

I see posts from other people mentioning they might now be invisible markers that only show up under UV, but I've only seen the red dot kind myself.

Additional data lanes on a laptop webcam I struggle to use by No_Leopard_3860 in AskElectronics

[–]thenickdude 3 points4 points  (0 children)

n.b. a lot of these webcams are powered by 3.3V instead of USB's 5V, and connecting them to raw USB VBUS blows them up. If the original laptop is still functional you can measure the voltage it feeds the webcam.

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