Replace wall light switch with Touch Sensor

If you are new to electronics Main supply projects are simply very dangerous. Try do something that is a bit safer to deal with. If you are going to ignore this best to use solid state relays as a method for switching.

http://au.element14.com/jsp/search/browse.jsp?N=2101+203128+110522010+110522278+110524065&Ns=P_PRICE_FARNELL_AU%7C0&Ntk=gensearch&Ntt=solid+state+switch&Ntx=mode+matchallpartial&locale=en_AU&appliedparametrics=true&getResults=true&suppressRedirect=true&isRedirect=&originalQueryURL=/jsp/search/browse.jsp%3FN%3D2101%2B203128%26Ntk%3Dgensearch%26Ntt%3Dsolid%2Bstate%2Bswitch%26Ntx%3Dmode%2Bmatchallpartial%26No%3D0%26getResults%3Dtrue%26appliedparametrics%3Dtrue%26locale%3Den_AU%26divisionLocale%3Den_AU%26catalogId%3D%26skipManufacturer%3Dfalse%26skipParametricAttributeId%3D%26prevNValues%3D2101%2B203128

Take a look at the iphone AC wall charger (USB), you can use the +5V from the USB output.

Hernán

Hi Richard,

Here are a couple of standard circuits to make a touch sensitive ligh switch...

Doug

Malcolm,

Thanks for your input.

I appreciate your warning about AC electricity -- very important.  I have been an electrician for years.  I'm just getting started in Electronics -- which I consider to be microprocessing, etc. (very different from wiring a house).  I was intending to use solid state relays (thanks, again, for the headsup on that).

My question is more -- presuming I am going to have to use DC voltage for the microprocessing -- of how do I turn the AC voltage to power the DC microprocessing components (instead of having a DC battery inside the junction box)?

Richard

Hernán,

Using a USB wall charger is a great idea!

The circuitry is, already, done!

I'll have to look into that (go tear apart an old USB wall charger).

Thanks.

Richard

Doug,

Thanks for the circuits!

I appreciate the circuits; I have been trying to figure out how to get started.

I have not, yet, analized your circuits; though, it appears that they are using 220V.  Here in America, we use the 120V; I presume I would just need to make some applicable adjustments -- is that correct?

This is great!

Thanks.

Richard

I did, just recently, find this already-made AC powered touch switch (at futurlec.com); however, it appears it is no longer produced:

Light Touch Switch

Want to replace all your light switches with a simple and cheap switch, that uses no mechanical parts and is completely safe. Well our new Light Touch Switch, is an ideal replacement. This simple and compact unit, may one day replace the convential light switch as a simple and cheap alternative. It is based on Capacitive Sensing and requires no contact with the sensor, instead the sensor is located behind the blank light switch plate. Hence, it is completely safe as no parts or electrical equipment is exposed. It is perfect for children and the elderly, who can operate it simply. The kit can also be used for many other applications, that require mains switching by proximity.

http://www.futurlec.com/TouchSwitch.shtml

Hi Richard,

The circuits should work as is with either 220 or 115 vac. The 15V zener limits the voltage to the chip in either case.

You can find a datasheet here:

http://www.farnell.com/datasheets/57961.pdf

Doug

There are already made wall touch switch in China since 2012, also wireless remote control

There are three different designs

#1. use a battery inside the switch to supply power to control circuit. cheaper, but you need to change battery often

#2. Introduce a natural line to the switch too, use the 110/220 VAC transformed to 5VDC, then power the control circuit. not user friendly, but reliable.

#3. induced current from hot line to power the control circuit.  most user friendly. but there is really technical skill behind this.

     Most such designs have a big problem of blinking of light. To kill the blinking, they also supply an "adapter"

     the "adapter" is nothing but an extra load of 5 watt. YOU ARE WASTING EXTRA ENERGY ON THIS ADAPTER.

    In earlier 2015 I just found a such design without wasting extra energy.

You can search eBay by wall touch switch wireless remote control