preview of latest project

i'm still drafting my blog entry, but I wanted to toss these pictures out ahead of time.

six key capacitive proximity sensing touch pad:
**broken link removed**

six zone sprinkler timer:
**broken link removed**
yikes, need to clean up that flux!

large format pictures:
https://projects.dimension-x.net/pictures/touch/pcb3_cmp_lg.jpg

before:
https://projects.dimension-x.net/pictures/sprinkler/pcb5_cmp_b4_lg.jpg

after:
https://projects.dimension-x.net/pictures/sprinkler/pcb5_cmp_aft_lg.jpg

pcb fab work was done by Custom PCB ... ordered on Tuesday, had the boards in hand the following Monday!

You do nice PCB artwork DIY, what's the pad on the lower right?

I saw the touchpad on your website. Hows it coming along?

blueroomelectronics said:

You do nice PCB artwork DIY, what's the pad on the lower right?

Click to expand...

thanks

that's for a surface mount 12mm battery holder, for the RTC on the flipside.

souper man said:

I saw the touchpad on your website. Hows it coming along?

Click to expand...

the touchpad works great! a nice PCB not to mention some super expensive polyester capacitors have the touch sensor working better than expected. The controller is coming along, migrated the software from my prototype board to the 'production' board last night.

since i mentioned it, here is the prototype pcb. it is really ugly and has a couple design flaws - but it let me develop 90% of the firmware while waiting for the real pcbs, so it served purpose. need to desolder those expensive relays!

**broken link removed**

Heck, even the prototype is pretty impressive.

thanks Mike.

This pcb is probably my best double-sided work thus far. Instead of a peel 'n press sandwich I ironed one side, drilled a few holes, lined up the second side and ironed again. this damaged a few traces on the top side, right in the center of the board, you can see where I crudely filled them back in with a marker. Next time I'll be a bit quicker with my application of heat, I think i'm cooking longer than needed for pnp.

**broken link removed**

The touch sensitive one looks really cool!

Out of curiosity, did you try any other circuits for touch-switches before you decided to go with the QProx chip? I may be doing a similar project in the future and was wondering if you had any input as to whether any of the other ways are worth-while.

i poked around a little, but nobody else really had anything as easy to use as the QProx ... and now the thing is being discontinued, replaced with a more complex chip in a less friendly package!

The overall simplicity of the circuit is why I chose the qprox... it's one easy to handle chip, six capacitors and a 10mhz resonator

The reason it's being discontinued I think is because of repeatability. a lot of experimentation is involved in getting the sensor pads the right size and finding the right value for the sampling capacitors. the newer chips are 'smarter' and more flexible in their configuration. but I'm not out to mass produce anything, so I don't mind a little fiddling to make it work right.