Single CMOS NOT Gate/Inverter

by andy70707

7.5K123

Intro: Single CMOS NOT Gate/Inverter

Ever needed a single inverter without having to take up valuable board space with a 14-pin hex inverter chip? If so, this is an instructable for you. This is a very easy logic gate to make, it only requires two components. Although it seems like one of the more complex logic gates, it is actually probably the simplest to make. It only takes a few minutes to make, fits on a 4x4 stripboard, and connects via a 4-pin header (Vcc, GND, A, and Q).

STEP 1: The Parts

Here is what you'll need for this instructable:
1x  N-channel MOSFET (Can't be a JFET). I used a 2N7000.
1x P-channel MOSFET (Can't be a JFET). I used a ZVP3306A.
1x 4-pin PCB header
 1x 4x4 piece of stripboard (matrix board works too. I usually avoid stripboard, but in this instance, it only requires one cut and join, so it's easier to use than matrix board, and a bit cheaper).
+Usual tools (Cutters, pliers, soldering iron+solder, saw for cutting board, stripboard cutting tool, small drill bit, or knife)

STEP 2: Preparing the Board

This step is really simple, you just need one cut in the board, and one join, as shown in the picture. If it is unclear, refer to the schematic or PCB layout on the next step.

STEP 3: Assemble the PCB

Assembling the PCB is pretty straightforward. Study the PCB layout and schematic below, Make sure the P-channel MOSFET is behind the break, with the bridge at the top. Check the polarity of them carefully too, but other than that, it's a pretty easy circuit.

STEP 4: Finished Product

When done, you should have something that looks like this. Test it with a breadboard, I connected Vcc to 3v and to A through a push-to-make button, GND to 0v, and an LED from Q to GND. When on, the LED was lit until the button was pressed, so the circuit works, When the logic on A is 1, output Q is 0, which is the purpose of the inverter. I am not sure about the min and max voltages, but I have tried it on 3v-5v and it works fine. This should also depend on the MOSFETs you use.

I may make more instructables on individual logic gates if I get good feedback on this one, leave any requests for what gates you would like to see in the comments.

2 Comments

REB352 5 years ago

The gates of the FETs should never be left floating. In this example, when the pushbutton is open, the gates are at an indeterminate logic level. The gates should be pulled to the negative rail using a resistor. The resistor value is not critical - perhaps in the range of 10-100K.