Sunday, September 30, 2012

Capacitive touch sensors.. 
(are cool..)

Sensor board back and front.

For my boat's interior I figured that LED strips would be just right in terms (low) power use lighting. The LED strips are mounted so that they provide indirect light and to switch them ON and OFF I wanted invisible 'hot' spots on the wooden side cabinets.

First thing that came to my mind was to use a QT118. I've used this chip before and it's proven to be a reliable capacitive touch interface.

As the diagram shows, not many components are required to make it work.

And the resulting PCB..

These two boards are mounted to the back of the cabinet facia. A strip of aluminum tape connected to the board acts as the interfacing / sensing area.
All solid state, no moving contacts. Self adjusting, automatic gain. Capable of switching somewhere around 8A. (more than enough..)

AT42QT1012 vs. QT118
Atmel now retired the previous QProx QT11x series and put the AT42QT1012 in place as the QT118's successor. It comes in a very small package (SOT23-6) which could lead to smaller board design compared to the SO-8 package that houses the QT118.

So I designed a board for the newer part first and found that I could not get it to work as reliable as the QT118, a pity... More experimenting probably needed.. 
Still having two QT118's in my stock I figured that, although it's now oboslete, it was still worth a board design.

A round PCB, why not.

The PCB has an integrated sensing area, so the board can be used directly behind a dielectric surface. In the end I decided to connect to a remote sensing surface.

Tuesday, January 25, 2011

LED Pong Clock

Pong Clock
This clock is my version of Nick Hall's Pong Clock

He uses an Arduino UNO with prototyping shield to glue the logic bits and pieces together.

I wanted to make one that looks good, without using Arduino. So I designed a custom pcb for this clock, with all the goodies on a single board. So DS1307 RTC, buttons, LED's, backup battery, beeper, and a future IR interface. PCB design features a QR code with pcb version and maker, to add to the geekiness.

I sandwiched the boards between two sheets of acrylic, this makes it rocksolid. It's a very touchable brick on my desk now.

A sheet of automotive anti-sun film sticks to the front of the displays, to enhance contrast.

My firmware has minor modifications to the original; startup message, beeper function etc.

Firmware is a work in progress...

Fun project, with many thanks to Nick Hall. Visit his blog, he shares firmware sourcecode, thanks for that!

pcb design (in mirrored view)

Action shot...

On request, the circuit diagram..
Straightforward as can be..

Sunday, June 01, 2008

16f688 serial LCD

Serial LCD

Sandwich opbouw

Voor een recent experiment was een (beperkte) seriĆ«le output terminal nodig.
4 regels van 20 karakters op een HD44780 LCD zijn hiervoor voldoende.

Sparkfun heeft een "serial enabled lcd backpack"

Dat ontwerp is de basis van dit project, echter met een uitbreiding voor de negatieve hulpspanning voor het LCD. met een 555 wordt deze opgewekt.

Geheel draait nu de Sparkfun firmware zonder aanpassing voorlopig, deze werkt prima.

Print ontworpen, werkt prima, zonder ontwerpfouten, verzilverd.

Friday, May 30, 2008

2x FT232 USB serial interface

Na een tijdje behoefte aan een tweede, identieke interface, dus nog maar een print ge-etst. het resultaat is behoorlijk identiek geworden..

Bovenste print is oud, onder is nieuw..

Wednesday, July 27, 2005

USB RGB temperature indicator

De RGB temperatuur indicator is gedeeltelijk af, hij werkt!
USB communicatie werkt okay, PIC werkt zijn programma af, gaat allemaal goed.
Wel een probleem nog aan te werken: De USB controller wordt iets warm, het lijkt erop dat de pic wordt gevoed via de Tx lijn van de CP2102.

Probleem oplossen
DS1820 insolderen
Software schrijven

to be continued....

(close up van de USB controller, met glasvezel stof...)
(CP2102 is maar 5x5 mm, dus kleine contactjes...)

het schema, omgebouwde versie van deze website.

Thursday, July 21, 2005


USB interface met FT232 BM,