I've downloaded the free version of Eagle. Looks complicated :S Watching a tutorial.

I am ever so slightly tempted to buy some titchy tiny SMD Atmega chips to make it even tinier. But that would be more difficult to program as a 4MHz chip. The DIP chip I can stick in another board then put in my wireless sensor. And I do already have about 10 DIP 328ps.

Sorry. :$


(no I'm not)

It's some pretty fine sphincter control, that's for sure.

Not used Target, but from the electronics 'club' thing I frequent at uni they have this to say on their wiki:

 

Designing the PCB

We tend to use software called "Target".  This is mainly a compatibility issue; we have it, we use it, we get good at it, so others use it, etc.  We certainly don't pretend it's the best software in the world, but it's quite cheap, there is a free student version available, and there is a lot of local expertise (and libraries of components).

Don't expect Target to do anything except schematic-capture and layout.  Though the software can do electrical simulations and physical 3D modelling, we almost never have the circuit or physical models required for the components we use.  Anyone got a SPICE model for a microcontroller?!!

Our version of Target lets us design up to 4-layer boards with unlimited nodes.  The student version is more limited.

There are lots of other PCB layout programs, but decent ones tend to be expensive.  There is an open-source program call KiCAD which is growing in popularity, and has a very large user base and support, so that may well be worth considering in future.  However our local expertise with Target counts for a lot.

All PCB layout software produces "Gerber" files, which are just pictures of the layout for each of the layers that make up a PCB.  Once you have those, you have to consider how to actually make the thing.

I've had a little play with Eagle and got a rough board designed. Not as difficult as it looked for a simple design. I've used the autorouter for the traces. Looks about $14 for 10 PCBs. Bargain. I think I might have to order one :)

:D the future is awesome. Mostly. If you live in the West. If 14 dollars doesn't represent 2 weeks income. Humans suck.

Yes they do suck (NJ). Maybe I should donate my temperature sensors to charity when I received them.

I heard a statistic on More or Less. I can't remember exactly what it was, something to do with if you work minimum wage in this country you're in the top 90% of pay in the world.

Sounds about right, bloody economics.

Here, I did something for the Rpi & Arduino users!

Before I properly design my PCB I'm going to try and make a unit that works with a 18650 rechargeable lithium ion battery instead of AAs. I should be able to rip some out of an old laptop battery if they still work.

I haven't got many 3.3V boost thingies (needed for the temp sensor) for my current setup and they're not that cheap. Should be cheaper to use a zener diode/something else to drop the 4.2V for the RF24 radio.

12 of them in this battery :O I hope they work still.

And assuming they're genuine they're all Panasonic ones so should be decent quality.

Surprisingly that worked. With a normal diode, not a zener. Used the forward voltage of the diode to drop the Li-Ion voltage down to the voltage the radio works at. No voltage regulators needed now, and the DS18B20 temp sensor will work at all the voltages. I'll just have to be careful not to short circuit anything and blow up any batteries.

Do you need to be careful with Li-Ion batteries not discharging fully?

Yes, looks like it. Just looking it up and they shouldn't be discharged to under 2.4V. All the cells in the laptop battery are 2.2-2.3V so maybe I shouldn't be using them. The one I charged didn't explode though.

Do you have a 18650 battery charger?

Yes, just got one for my bike lights.

My !!/really exciting/!! Atmega 328p programming board.

It's got the 16MHz crystal and caps so I can program my chips to run at 8MHz off the internal clock before sticking them in my temp sensors (only have 1 so far though).

Forgot to upload the picture.