AVR Freaks

A few leds should always be included, add header pins to them so you can jumper them to wherever you need.  Maybe 2 switches should also always be included, with a connection header.  A pot was also mentioned.

Or perhaps you prefer to solder in everything you want & have no excess---its a tradeoff.

Polyswitch (or fuse) on power input

Perhaps define a spot for a secondary regulator (diodes,reg & caps)---in case not everything runs at the same voltage (ex: feed in 15V, regulate 12V & 5V,  feed in 12v regulate 9V & 3.3V )

SMPS from Recom, are those those 3pin 78xx replacements?

Less soldering than a discrete solution, but trivial.

A shunt resistor together with a 2pin 0.1" header to measure the voltage over the shunt can be handy.

This 2 pin header can then also be jumpered if no current measurement is needed.

I like to have an obvious way to connect measurement equipment to GND.

2 holes of around 2mm diameter and 15 mm apart let you easily add a piece of copper installation wire (2.5qmm) for a big loop to connect the GND leads of your oscilloscope.

Layout for an UEXT connector may be handy.

It is a 10 pin IDC with UART, I2C, SPI & Power, specified by Olimex.

I also keep my development boards small, and then use a board to board connector (or IDC cable) to connect it to a regular protoboard.

Easy access to the unregulated supply will make it easy to add a 2nd voltage regulator for a different voltage.

Also: after a bit of practice soldering (the larger) SMD parts is easier than soldering through hole parts.

- No constant turning of the PCB

- Not getting confused by mirror images anymore.

- No components falling off.

- No clipping of leads for resistors, capacitors etc.

Also: I see you use tubes to isolate your wires.

I tend to use lacquered copper wire, with a hot (temperatur controlled) Iron ( 400 to 430 Celcius).

This is hot enough to burn through the lacquered wire, with no need for stripping the wires or cutting tubes.

(Download or open the picture in a separate tab to view it in higher resolution)

Here: https://www.olimex.com/Products/Modules/UEXT/

Or there's the XPlained Pro standard.

Or any number of other "standards" - proposed by every other board maker.

Also: I see you use tubes to isolate your wires.

we call it, "sleeving".

I like to have an obvious way to connect measurement equipment to GND.

very important!

I've seen some video of the elm-can (like) soldering.

Soldered with a big shaky iron, and often other wires are touched while soldering a wire next to it, which leads to that wire disconnecting and a lot of extra work.

It is made more like an piece of art, then as something practical.