Hey there. A while back (almost a year ago) I bought a kit on synthrotek.com. I was eager to try out and explore the Nand 4093 oscillator chip. Because of where I live, I couldn't purchase the chip and other components separately, so I decided to order the PCB online with the chip and the components. When I received the kit, I put it away. And It got lost in time, until I found the kit hidden in my room. So I thought I'd make it and post it online. It's quite fun to make a project when you receive a kit, I mean, all you have to do is to put the components in the PCB, solder and make holes in a project box so I could house the synth. The real challenge would be to make it from scratch, layout the components and solder respectably on a plain prototype board according to the schematic. Either way you get a fancy synth to play around with.
There are two oscillators made with the Nand gates of the 4093. The 100K pot controls the pitch of the gated oscillators on IC 4093. The switches allow for; either pulse ore gated/osc mode, or channel on and off.
For more information on the Nand 4093 IC click here.
Credits on the creation of the PCB board go to synthrotek.com

Here is a video demonstration of the synth:

Step 1: Tools and Materials

So the materials and tools you will need for this build are mainly electronic components, you might find everything close to where you live. You will probably be able to find everything online.

Materials:

X1, 4093 IC Quad Oscillator Chip.
X1, 14-Pin Socket.
X1, LED: Which ever colour will do, although I do recommend a red coloured LED as it will be used to indicate if the synth is on.
X2, 1 Mega Ohm linear Variables resistors or potentiometers.
X1, 100K linear Variable resistor or potentiometer.
X1, 100K Audio Variable resistor or potentiometer.
X1, SPST Switch.
X2, SPDT Switch.
X1, 1 Kilo Ohm resistor.
X4, 100 Kil Ohm resistors.
X4, 100 nF Ceramic Capacitors.
X1, 2.2 uF Electrolytic Capacitor.
X1, 100 uF Electrolytic Capacitor.
X1, Quarter inch or Half an inch mono female jack.
X1, DC Jack or a 9V battery clip.
X1, Project box or enclosure of some sort.
X4, Knobs for the potentiometers, only if you wish so.
X1, 9V Battery or you could also have 4XAA running on less voltage. (I had AA's batteries laying around, so that's what I used) - These are optional if you are using the 9V battery Clip instead of a DC Jack.

Tools:

Wire, probably about a meter and a half or so. (5ft)
A PCB, you can either buy a plain PCB or buy a pre-made one here.
Drill and some drill bits.
Screws of course.
Soldering Iron.
Solder.
Tweezers.

The usual tools.

Step 2: PCB Wiring and Schematic

At this point, there is two ways to go. One is to buy the PCB pre-made and the other one is making your own circuit on a naked prototype board. If you decide to buy the board you have to insert all the components in there respective spaces and solder. If you want to make your own circuit you will have to follow the schematic I made based on the PCB diagram from synthrotek.com or directly follow the PCB schematic. I made the schematic in frirtzing to make it a little bit more clear.

Step 3: Housing

Once you have all your components soldered to you board, I highly recommend housing your synth. I bought a little project box and then drilled different holes with the drill. I made 8 holes in the front of the box: four potentiometers, the red LED, two switches to turn on and off each oscillator and a switch to turn the synth on or off. And on the side of the box: the audio female jack and the dc jack. Once after making holes push everything inside. I had the battery pack which almost didn't fit inside, I actually had to use my dremel to cut pieces of plastic for everything to fit.

Step 4: Wrapping Up

There you have a basic synth you can make with the nand 4093, remember you can hack this in various different ways. Instead of using potentiometers you could use different variable resistors like light sensors or slide pots. You could also make different projects or synths involving the nand 4093. I highly recommend checking this site for more information: http://www.doctronics.co.uk/4093.htm
I also found a really cool project based on the nand synth: http://hackingbynight.wordpress.com/2008/12/21/gated-nand-drone-synth/