Dual H-bridge Motor Driver - L293D IC

Parts required

Parts Details Quantity
L293D IC
L293D Motor Driver IC
Motor Driver IC 1
16 Pin Socket
16 Pin Socket
8x2 DIP Socket 1
Perforated board
Perforated board
With 20x12 or more holes 1
Connecting wires
Any color of your choice 10-12 small pieces
Linear Voltage Regulator 1
Male breakaway headers
Male Breakaway Headers
40 pin single row headers 1
Solder Lead
Lead / Lead free 50-100 gms
Solder Iron
Solder Iron
Preferably temperature controlled 1
Building the circuit - Part I

Before building the circuit, I prefer using DIY Layout Editor to replicate the circuit. DIY Layout Editor is a free PCB design tool which I would highly recommend if you are someone who works like me :)

L293D Schematic

Let's begin building the circuit. First, add 16 pin socket to the board as shown in the image. As usual, click on any image for an enlarged view with higher resolution. If the step requires soldering, then the soldered part is highlighted to help you with soldering.

Add socket into PCB

Solder first and 16th pin of the socket to copper side of the board.

Solder socket

Add two 2-pin headers (two 2 pin headers) to the left of socket. Make sure there is at least a gap of two holes between socket and header.

Add 4 headers to left


Solder horizontal pins together.
The vertical two pins will be later used to connect the first motor. The other two pins are there in case we need to use this output for some other reason. If you do not need this, you can use a single 2-pin header and plug it vertically and individually solder the two pins to the board.

Solder left headers

Add two more 2-pin headers to the right side of the socket with a minimum gap of two holes between socket and header. The gap makes it easier to plug other female headers once the board is completed.

Add 4 more headers to right

Solder these two headers similar to the left headers

Solder right headers

Now solder the bottom pins of two headers on either side to Pin6 and Pin11 of the IC, as shown in the image.

Connect to pins

Add two more 2-pin headers to either side of the board. These two headers are input pins which are later connected to microcontroller.

Add headers above existing headers

Solder each pin of the header to the board, but take care not to solder them together. As shown in the image, solder the top two header pins on either side to Pin2 and Pin15 respectively.

Solde two four headers

We need two more 2-pin headers, one header for enable pins and other for +5V. Push the two 2-pin headers as pictured below. Let the first two vertical pins be in the same line as the socket pins.

Observe carefully how the soldering happens from here on if you are not sure what is happening. I can assure that you would have a complete working circuit if you follow the tutorial exactly.

The top two header pins are soldered together. One of the pin in bottom header is soldered to Pin1 of the socket. Click on the image to understand what I mean.

We will add two more pins for powering the circuit (we will call these two pins as Power pins to make soldering easier).

Solder each pin of the header to the board, but do not short them.

Add a 7805 voltage regulator such that the center pin is in line with power pins. I have bent the regulator to make it look compact (or I just like to keep it like that). If you do not want to bend it, keep it upright.

The top lead of regulator is input (Vin), middle lead is ground (Gnd) and the bottom lead is output (Vout) which gives a regulated +5volts.

Bend the regulator leads as shown. The middle pin almost touches one of the power pins. If the regulator lead (the middle one) is too long such that it touches both the power pins, cut it short. Vin should also be bent in the same fashion. Vout is bent such that it touches the headers above enable pins.

Tutorial index:

  1. Motor Driver and H-bridge basics
  2. Parts required and Building the circuit - Part I
  3. Building the circuit - Part II

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