Guide QT110 Touch-Sensitive Button Guide

To tap into a wire, it's good to cut it, bare a little wire on each end of the cut & tin each of the two ends.
Then tin the end of the additional wire you wish to use.
You can then slip on 4 - 5 cm of heatshrink, say ~5mm diameter would be good in this situation.
Then secure the three tinned wires together, so that approximately the orginal length is retained, and solder away - keep the heatshrink far away down the end of the purple wire - once the joint is cool, you can slip the heatshrink back down - heat with a hairdryer up close or wave a lighter under it brifely - if you put it on the right side of the joint, then everything will be covered up very neatly & professionally.

I've been reviewing & making a small changes here and there to the double click circuit, and here's the latest version. It's got a couple of filter's whacked in to keep the QT113 happy/noise free. The QT113 only needs 2.5v!, the 555's only need 4.5v and voltage drop through the filters should be very minimal.

It seems all the QT113's here are active low. I'm thinking of getting an smd version to keep costs low cos i'll be getting 10 of them - a couple of separate pcs & a couple of spares.

 

Cheers for all the help

I'll let you all know how I get on.

I hope your "double click / touch" button gets working the way you like.

As for now I just ordered all my components, and my first dremel!

 

Im not sure about everyone else but the images are no longer working for me. Would anyone be able to upload them again please?

edit: talking about page 1

 

Same here, no images on the first page.
I second Matts request.

 

Sorry guy's but the first post is about 2 1/2 years old!
I don't know if anyone has those images, but the people active on this thread still may help
Just ask about what it is you need, I'm sure you'll get some help.
If not, try starting a new thread with your specific problem / question.

 

I might as well throw in an update: double-touch switch works 100% as planned. The fastest speed is nice so there's no need for the 250kvr, i omitted L2, and L3 is around .5mh - which is enough filtering. I tried a 100nf (.1uf) sensitivity cap, which is too small i think - you need a ~5cm square sensor just to be able to barely sense through a 3mm plastic 5.25" bay cover! I'll try other values, but i think 300-400nf (.3-.4uf) will be good. Here's a pic of the smd QT113 with the .1uf cap and leads soldered:

I used smd cos i got 10 of these guys so it saved me $30 - i forgot to put a jumper setting in this pic for size reference - a jumper is actually bigger than this little ic
Front view:

You can barely see the QT113 under the three big green caps on the left. Two jumpers & hdd screws are in this pic for size reference. Next is the front view complete with wiring - note the shielded electrode cable to reduce noise.

And last is the rear view of the pcb tracks - hold up a jumper to your monitor, and shrink the pic to get a life size view

This is essentially my first prototype - it will be pretty easy to eliminate at least 4 of the yellow wire links here on future versions.
Thanks to cpemma for the clapper circuit & cinnander for checking my circuit
UPDATE EDIT:

Here's build numer 2 - damn build 1 looks dodgy in comparison It's the same size as before but the pcb has been filed down to size so there's no excess pcb to make it look bigger. You can see the QT113 smd chip easily now so you can tell that it is a little smaller than a jumper setting. 5 wire links are now on the top side and the resistors have their legs covered with matching wire tubing.

It's out of focus There's only two rear links now, but if you include the 5 front links, i've only managed to eliminate 3 of the 10 links from build number 1 - i will probably eliminate another 2 in the next build.
MODDED LIGHTS!
I modded my desk/work lights a few days ago, and have been re-shooting various things, including the second double-click circuit:


The lighting isn't perfect, but it's pretty good and kinda close to white, only a lil bit of darn yellow left

 

so how much does one of those circuits cost?


when i search for QT113 on digikey it give a whole bunch of different ones. which one do i choose?

link: http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=1966444;keywords=qt113

also could you link me to a socket for the qt113 on digikey?

thanks

 

The ones that labelled: QT113H are the active high ones. You can order any of the QT113-... ones.
In the "description" coloumn it states wether the ic is "DIP" or "SOIC" The two 555 timers on my cicuit are DIP and my smd qt113 is SOIC - if you want to put the ic in a socket you have to get DIP. I didn't use sockets & i don't mind soldering directly to ic's so i didn't use sockets and got the soic qt113 which was like half the price at farnell.
I spent $41 at farnell + shipping + gst which came to $54, and i spent $15 at a local electronics store for things like caps & resistors & pcb which were a bit cheaper than farnell, so thats $69 all up, and i have enough parts to make 5 touch switches & 5 double-touch switches. It cost me about $4 for each touch switch & approx $8 for each double-touch

edit: i can't link the exact url, it just goes to their search page - do a search for "dip socket", select pin size "8 (2 x 4)" and "tin - undefined" and then "apply filters" - any of these are fine, get the cheapest ones

 

ok. so i use the DIP version. but there are a whole bunch of them on that page. which is the correct one?

what's the difference between active low and high??

you mentioned trouble with sensing through drive bay cover. can this be improved or do you need a huge electrode?

for the regular touch circuit i just need the qt113, socket, and capacitor?

what kind of capacitors do i use? i know what number thing but what kind? maybe a link or part number?

once you finalise your double touch circuit can you post updated schematic and a complete parts list?

thanks!

 

I'd get this qt113 cos it's active low (not a qt113h) and it's the cheapest one with a minimum quantity of 1.
The active low's have numbers such as qt113-s and qt113-isg, the active high's have numbers such as qt113h-s and qt113h-isg.
You want active low if you are gonna hook it up to a mobo or an earthed dvd eject button, or the earth side of an led, etc...
Active high versions output a 5v signal instead of an earthed signal, which can come in handy for other things...
I plan to try other capacitor & electrode combinations soon, so i can only guess that ~400nf will work ok with a ~2cm square electrode. This cap is 430nf, should work well, but you may want a bit more or a bit less sensitivity - it depends on the thickness & material of your front panel, and it depends on how big & thick & material of the electrode - so try it out and you'll find out soon enough! And yes, all you need is the ic, the socket & the cap - Dont forget to use shielded cable for connecting to the electrode - it will help with the sensor accuracy.
I built the double-click circuit on the fly from the circuit diagram above, and i squashed it as much as i could, it doesn't have to be that small - it can be built exactly as it appears on the circuit diagram tho, you only need to rearrange the two 555 pinouts.

 

ok so no changes to the schematic (except for sensitivity) are needed?

i dont know how to read it to know what the parts are. could you give a list of what they all are? i dont need links or anything. just list and name of parts.

thanks !!

 

I'm guessing you're thinking of making the double-click version? Trust me, if you can't read the schematic well enough to identify each part, then you will run into many problems when building it! You can learn heaps about reading & building circuits by getting something such as an audio amplifier, and really study it so you know exactly how it has been designed - if you have built kits already, go through all the instructions again, and compare the schematic to the circuit board - follow each connection to figure out how the circuit diagram has been put on the pcb - and of course, there are plenty of electronics books out there to learn from...

You should make the basic touch switch for now - it's easy to hook up, so you shouldn't have any problems except for experimenting with electrode size and possibly even capacitor sensitivity size - you may want to order a few different caps to be prepared for this! It id reccomended to not go over 500nf!

 

i can read a schematic as in I know how it goes together but i dont know what the little symbols mean and what parts they are. thats what my dads for. he knows all that stuff. I will be able to build the circuit but by just looking at the circuit I do know exactly what parts I need. If you could just list the parts you used thats all I need. I havent learned much about electronics so I dont know what those squigglies are.

 

so why didn't you just get your dad to explain?
Ok, so the resistors are labelled: R7, R8 etc... The variable resistor is labelled VR7
The capacitors are labelled C1, C2, etc. It is important to note the polarity with electrolytic capacitors which are used for the larger values - you can get bi-polar or big mylars but they are unneccessary expenses.
I think by "squiggles" you mean the inductors? They are just the coils of wire, L1, L2, L3. I left out L2, so it is basically now just a metal track on the pcb. L3 is the big coil wrapped around the ferret core on my circuit, and L1 is the small coil of wire. My L3 is probably around .5mh-1mh and my L1 is around 100uh.
Note the circuit will work fine without any of the coils installed, all the coils do is provide smoother power for potentially more reliable operation - if your psu is really good then they won't make a difference, and if your pc psu is crap then you would want large L2 & L3 coils.

Good luck making the circuit, there are lots of little traps for the inexperienced when making a circuit like this! You should definitely get your dad to help you out!
I was thinking of making a guide, cos all i have really posted is a couple of circuit diagrams to get help in designing this circuit, a few quick explanations & a few finished photos - which is far from a guide, it's barely a project log, it only meant to be a contribution to this thread It takes alot of time to make a nice guide, if i had more free time i would make one...

 

i got a Silverstone Strider 750 Watt PSU. i think its good. so L1, L2, L3 i may not need. if i do put them in which one is most important or does it not matter.

ya he will help me with some of it. as long as i know what is what on the schematic i will be fine.

i like to try things myself without him always helping

thanks again!

 

Most important are L1 & L3 - i used ~100uh for L1 & my L3 is only like ~.5mh cos i'm gonna be using a nice seasonic psu - i'd suggest the same for you since you will also be using a nice psu.

Or you could leave them all out... it may work 100% fine, it may be a little unstable? i dunno one way to find out

 

i'll do the same as you. thanks

 

Hi all,

Sorry about the pictures in the first few posts -- I moved some stuff around on the webserver and the image links should be working fine.

Glad to see some new info in this thread!

 

Viva gongzero! The man that taught me how to make a touch switch

 

The easiest way (if you can find a suitable connector) is to plug into one of the motherboard headers that has that line. RTFM, check for +5VSB power pins on 'wake on LAN', 'chassis intrusion', 'infra-red module', etc, headers.

Another easy way of tapping into a wire is to use one of the snap-splice connectors sold for tapping into car wiring.