W.meri's making shi- stuff thread

I like making stuff, so I figured I’d start a thread to keep track of everything. Big projects will probably get their own threads, but the little things will just get tacked on to this thread. Can’t guarantee any consistent updates since this entirely relies on what time I do or do not have, but I’m hoping to be fairly regular. Discussion is welcome!

Also, no community projects and/or DIY category?

Table of Contents


#DC Fan Hub

This one came about because sometimes I need just a little bit of airflow, but I don’t want to use a bulky contraption. I also have a few spare case fans floating around. Put 2 and 2 together, and you get a power hub.

Schematic is a bit weird, but it was like the third thing I ever made in EAGLE ↓

It’s a little hard to see since the layers overlap, but the top layer of the board is just the +12V plane and the bottom is ground. Everything is through hole too, so didn’t even need any extra vias ↓

Fresh from OSHPark ↓

And after soldering. Disregard the rubber fan pin propping it up ↓

Original Files


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#Power Button Helper

Ever needed to troubleshoot a motherboard outside of a case and don’t have a spare power button hanging around? I know it’s possible to just use a screwdriver or what have you to bridge the contacts, but god forbid you drop the screwdriver. Also, buttons are easier.

I popped in a spot for an LED as well. Power LEDs are handy ↓

I used the layout for Omron B3F switches. They’re tiny and of good quality ↓

It’s literally the size of my index finger ↓

Partially soldered (forgot which box my LEDs are in). Was thinking a couple of the empty holes would be nice to use for stabilizing some 3D printed button caps and the other holes for mounting to a 3D printed case ↓


#Audio Switcher

Pure analog goodness. This one is actually super simple, but rather useful in my opinion. Three audio jacks hooked up to a DPDT switch. With this it’s possible to switch between 2x inputs and send it through 1x output OR have 1x input and switch between 2x outputs. So say you have a DAC, headphone amplifier, and a speaker amplifier. This thing would allow you to switch between the headphone amplifier and the speaker amplifier literally at the push of a button.

Schematic is a mess, but it kinda has to be because of of how everything is paired up ↓

I think I may have to split the grounds apart to prevent grounding issues. Haven’t run into any really issues yet however ↓

What I didn’t realize when making the package for the switch is that I got the two pins that are attached to the case backwards. The pin on the left should actually be towards the middle, the pin on the right should be towards the top. I’ve already fixed the package in EAGLE though and updated the board file, so any future uses should be fine ↓

Push the button to make the magic happen ↓




Since I forgot to do it when making the initial posts, I added links that go to .zip files that contain the EAGLE files, BOMs, and any pictures if anyone wants to get their own boards and/or spin something off.

All I ask is if any of my designs are used for commercial purposes to please PM me first, give attribution, and release under a Creative Commons or similar license :slight_smile:

(i.e. Creative Commons Attribution-ShareAlike 4.0, which all of these designs are intended to be under.)

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[details=Fan Hub]It actually works well.

I also updated it a little for PWM compatibility. Or at least that’s the plan, but I gotta test first.

[details=Power Switch]Works perfect. Just need to design a case for it and it should be good to go.

[details=Audio Switch]Updated the layout of the switches so it should be more compatible with a slightly wider variety of switches. Also changed it to a star ground of sorts, although I’m not sure if it would matter much since there seems to be an ongoing debate in whether or not a ground plane or star ground is better for audio purposes.

#New Stuff

[details=Headphone Amp]I’ve been tinkering with the idea of making an amp in the spirit of the O2, using slightly better parts and a smaller design. Mainly because it gives me something to do, and with enough updating I think it could be released under a slightly more open license. I just can’t decide what to do with the three “sections” of the amplifier.

  1. Power Regulation - The O2 has a very simple setup, but it’s not super efficient and requires the use of an AC-AC adapter, not a more common AC-DC adapter. I can’t decide if it would be best to keep the linear regulators and just update parts, or swap to switching regulators like the ADP5071. Switching regulators would make it slightly more efficient and would allow use of the more common AC-DC adapters. There’s an ongoing argument about whether or not switching regulators introduce noise into audio signals or not (I vote no)
  2. Power Management - The power management circuitry in the O2 works, but it can thump when turning on/off sometimes. The other option would be to use a relay setup, like the Super CMOY.
  3. Amplifier Section - There are two routes here to match the performance. The first would be to more or less follow the O2’s example and use one opamp for gain, and two others in parallel for the primary amplification. With new opamps like the OPA1688 this would make for an amp that is about as powerful and have an even lower noise floor. The other option would be to go the buffer route with something like the LME49600. This would allow for an absurd amount of power, but would be a bit more expensive. Either way, implementing a SOIC/DIP adapter on the board itself would be nice, that way people could use a wider variety of opamps.

*NwAvGuy used a non-derivative license, so technically you’re not even supposed to change the parts on the board aside from what has been listed in the BOM. The problems arise when those parts go EOL or otherwise out of production, as is the case with the barrel jack and power LED. NwAvGuy seems to have fallen off the face of the planet however, so ehh?[/details]

[details=Keypad]Some people have probably already seen this, but I’ve designed a keypad using a Teensy 3.2 as the brains. This would allow it to either be a numpad or as a 20-key macropad, or both. It’s setup for PCB or plate mount switches, and even though it has places for LEDs, I don’t think the LEDs will stay lit when not pressed. In the future I might tweak the design to completely remove the LEDs and PCB mount compatibility just to simplify things a little before working on a design with persistent LEDs.

I’d need to order what works out to be about $70 in boards though from OSHPark at a minimum, so needless to say I haven’t ordered or tested the design yet.