Touch Switch

Hey everyone, welcome to the channel! Today, we're building a cool touch-activated switch using a CD4011 IC. This chip is set up as a flip-flop, which basically means it remembers its last state. Think of it like a light switch that stays on or off until you change it.

The CD4011 is a CMOS IC, which is great because it needs only a tiny amount of current to control it. Pins 9 and 13 on the chip are our set and reset points. They're normally held high (meaning they have a positive voltage) thanks to resistors R1 and R2.

Now, here's the magic: when we touch the "Touch On" points, we essentially ground those pins, pulling them low. This changes the output of the CD4011, which in turn switches on a transistor, Q1. When the transistor turns on, it activates an SSD relay (Solid State Relay), and that's what controls our connected device.

To turn the device off, we simply touch the "Touch Off" points. This brings pins 9 and 13 back high, turning off the transistor and deactivating the SSD relay. So, with just a touch at either the "Touch On" or "Touch Off" points, we can easily toggle our device on and off.

Using an SSD Relay (Solid State Relay)

We're using an SSD relay (Solid State Relay) for even more reliability and faster switching. An SSD relay uses semiconductor components to switch the load, so there are no moving parts. This means it has a much longer lifespan and can switch much faster than a traditional mechanical relay.

To use the SSD relay, we connect its input to the collector of transistor Q1. The output of the SSD relay is then connected to our device. The benefit here is that the low current output of the transistor easily controls the SSD relay, which then handles the switching of the higher current load to the device.