Here you can learn Step-by-Step how to build a motor driver Infra-red controlled with only two transistors !
The circuit has a permanent lit IR LED and a Photo-diode connected directly to a BC212 Base which will amplify the signal from and will feed it to a medium power transistor BD135 (Collector-Base). From this BD135 you will power a DC Motor, turning this way it's opposite to enemy ROBOT. If you connect you sensors differently you can simulate diferent behaviours according to BRAITENBERG (please see https://en.wikipedia.org/wiki/Braitenberg_vehicle)
Step 1: Cut a Small Piece of a Stripboard With 8x14 Holes
Step 2: Solder the Resistors
4 x 330R resistors fromTtrack 8 to Track 2
1 x 560R resistor from Track 1 to Track 4
I used four 330R in parallel because otherwise a single 1/8 W resistor of around 100R would BURN !
You can use any value lower for example 4x100R resistors and this will give max IR distance but will drive your IR LED to the maximum current so be careful not to kill it ! :D
A total resistor lower than 14 OHM will kill you IR LED for sure ( I have tested it) :D
Step 3: Solder the 1N4004 Diode
Solder the DIODE's Cathode (-) to Track 8 and Anode (+) to Track 4
Be careful with Diode's poles... negative side is the one with a grey strip, don't solder it wrong !
Step 4: Solder the Header Pins on Track 8 (Positive), 3 (Motor Out) and 4 (Negative)
Track 8 is the positive supply, Track 3 is negative pole and Track 4 is the output for the motor. Motor connects between Track 8 (positive) and Track 4 (BD135 Colector).
We will use a group of 4 pins to the Positive and 2 groups of 2 headers for Motor Out and Negative respectively.
If you want you can use an ERASER to help you solder the header pins and even to support you small circuit while you solder other components.
Step 5: Solder the BC212 and the BD135
Solder the BC212 (or any other PNP small signal Ex: BC557) and the BD135 for POWER !
Now be careful these are heat sensitive components they can burn by overtime to heat source like an SOLDERING IRON.
Step 6: Solder the LED's and Photodiode
Solder the LEDS (RED and INFRA-RED) and Photo diode (IR RECEIVER) as seen it on the pictures. Be careful with the polarities : Always remember photo diode is connected inversely as for the other LED you can see longest leg is the POSITIVE.
Insert INFRA-RED LED shortest leg (-) on Track 3 and longest leg (+) on Track 2
Insert PHOTO DIODE longest leg (+) on Track 3 and shortest leg (-) on Track 6
Insert INFRA-RED LED shortest leg (-) on Track 3 and longest leg (+) on Track 1
It's very important both PHOTO DIODE and INFRA-RED LED are ate the SAME LEVEL an very close to one another as they form a PAIR ! The closest they are the better they will work together !
A diodes and LED's face thei
Step 7: Finish Attaching the Motors and Supply...
Verify your tracks ! See if there is any short circuit !
Make an intentional short between Track 8 and 7... I meant it like that when I designed it for teaching purposes to see if my students could find the problem after the circuit was built !
Attach wires and power supply !
TEST-IT ! And enjoy your ROBOT !