Why not use wirewarap header type sockets with Rs & Cs mounted between the DIP legs so the assembly can be 3/10 wide instead of 5/10?
Got me curious as to if that would fit or not now.

That (wire-wrap DIP socket with long legs) was first thing came to my mind when I designed this, but they were quite expensive (the cheapest one I could find from Digikey was over $5.00).  I wanted to make it inexpensive and ended up with this design.  If you want 3/10, there is so called one-chip Arduino I remember.

Thanks.

Nice one!

Thank you!

Very handy for breadboard usage.

Yes, indeed!  I'm quite satisfied with this design. :-)

Since I introduced the JeonLab mini v1.0, I thought I could make it smaller and breadboard friendly.  So I designed a new version.  

This is yet another minimalist Arduino compatible board which means there are only core components: ATmega328p with Arduino bootloader, resistors for the reset pins and LEDs (power and d13), and a capacitor for auto-reset when you upload your sketch through external FTDI interface.  

I found there is enough space for resistors or capacitors between the PCB bottom and the breadboard because of the height of the header plastic part.  So I arranged those 3 resistors and a capacitor at the bottom layer so that only ATmega328p, ceramic resonator, and 2 LEDs can be compactly arranged on the top layer.  This fits very well on a mini breadboard.

It looks like this.

JeonLab mini v1.3 assembled 1 by DS2DYS, on Flickr

An example with external power (+5V, but it runs at about 3-5V).

JeonLab mini v1.3 testing by DS2DYS, on Flickr

You can upload your sketch with FTDI breakout board (e.g. Sparkfun).

JeonLab mini v1.3 on bread board with FTDI by DS2DYS, on Flickr

Its pin arrangement:

JeonLab mini 1.3 pins by DS2DYS, on Flickr

More detail and examples will be posted on my blog.

Thanks.

"the spirit of Arduino"  - It truely is!   

......a chunk of 12AWG solid copper wire and wrapped it up the body of the iron and the tip and had it poke out straight for a few mm from the tip......

I have done that sometime ago, too.   

Well, regarding the temperature, I think it depends on how large your target component.  In other words, if there is a large heat spreader like ground plane where you want to solder or a thick terminal, you need to increase the temperature.  That's the beauty of using temperature adjustable soldering iron.  In my experience, it varies from 650F to 750F. 

Also, as already mentioned by others, if the soldering iron's temperature is relatively high, you can reduce the time for the iron to contact with the component.   With this trick, at about 750F, by brief touches can solder small parts quickly and safely.

I love Weller, but too expensive.

You can always connect external power, but make sure the ground pins are connected together and don't mix up the positive powers.

oh, whoops. do I connect +5 to AVCC (pin20), as well as VCC and AREF?

Yes, you should connect +5V to AVCC and VCC.  Regarding the AREF though, if you are using analog input channels to measure some analog signals, you need a reference voltage.  Usually, simply connecting +5V along with AVCC and VCC to AREF will do the job.  So go ahead to connect all those 3 pins to +5V.  But if you want to use an external reference for some reason, then you should connect the AREF pin to the external source.  In this case, don't forget to connect GND pin to the ground (or -) of your external source as well.

One more thing about the AREF pin: if you are using only digital input/output pins and don't need analog pins, you don't have to connect AREF pin to any of those I mentioned above.

All right. It was not for PCB fab.  Since it is not far from me (us :-), I will try to visit them soon.
Thanks, frank.

Again, by putting a 0.1uF ceramic capacitor between the reset pin and the DTR, only when power up or new sketch is uploaded, it will reset.  I have a minimal Arduino as in  my blog with a FTDI breakout board and this capacitor for stepper motor control device with continuous serial command without any reset problem.

frank-- I have had a chance to look at the Sayal website, but I don't understand why you mentioned them.  They seem to carry some sorts of electronic parts but links are not really intuitive, lack of price and detail info.  I thought you recommended them as a PCB fab house but I couldn't find any link from their website.  Thanks anyway. :-)

You need a 0.1uF ceramic capacitor between the Reset pin of the ATmega328P and the DTR pin of the FTDI converter for the auto-reset.

Good luck! 

An example (simple timer) is posted on my blog with Arduino sketch. 

Thank you for your comment of the autorouting.  I know the manual routing would make it look better and fun, but I found the auto-routed one was not bad.  I still think the autorouting is good enough for many cases, but I definitely agree that the manual routing make your PCB look nicer. :-)   

Hi frank:
There was no errata.  They used to ship boards through their Singapore post but this time, they shipped it through Hong Kong post, I guess this took more time.
Anyway, the boards are good.

Yes, I love to use the autorouter of Eagle.  I had to move some components for the autorouter to process 100% but it worked like a charm within a second.

Sayal Electronics? No, I haven't heard about them.  I will google it.  Thanks.

Have a nice weekend, eveyone!