LCARS panels part 4 - Axeman's Nest

Jump to:
LCARS - the look
LCARS - electronics 1st part
LCARS - lighting and assembly
LCARS - electronics 2nd part

	Switch or push button The panel works as a momentary pushbutton: the output remains active until the finger is on the sensor (for a maximum of 10 seconds, after that the autocalibration will disable the output). You can see the behaviour of the circuit in THIS MOVIE. But if we look at the schematic in the part 2 of this tutorial, we'll see two pin (OPT1 and OPT2). These two pins changes the QT110H behaviour. They are now connected to +5V. If you connect them to GROUND instead, the QT110 become a switch, and the effect is seen in THIS MOVIE.
	QT110 or QT110H Someone told me that QT110H is no more produced. There is the QT118H that should be totally equivalent for our purposes. If for any reason you must use QT110 (or other QT11x with the output reversed) you can use this simple circuit to invert the output. This also allows the use of indicators to show both states, like in THIS MOVIE.
	Low voltage low current loads The QT11x outputs can drive digital circuits only (5v-5mA). If you want to control something bigger, you need a power stage. The easiest way is shown here: a single transistor output. The 2n2222a can switch loads up to 24v and 500mA. In THIS MOVIE you can see a CCFL switched by the panel.
	High voltage or High power loads Load decoupling In every circuit seen before, the ground of +5v logic supply and of the load power supply must be tied togheter. This is a big problem with many loads, like things that works with 110/220 vac, or everything you know nothing about (like the motherboard switch connectors :-) So, my personal advice is to ALWAYS use a relay to drive loads. The schematic is shown here, and in THIS MOVIE you'll see a 24v filament lamp driven by the panel. You SHOULD use a relay also when the panel is used as ATX power switch or reset switch. I warn you :-)

Click on the pictures to zoom.