how to make an optocoupler

When building the stepping motor drive board, I had a problem where my motor would take so much energy from the micro-controller I used to switch them, that the micro-controller would turn off.
The spikes in the power supply are big enough to destroy my expensive micro controller when I get it to work.
I realize that I need to isolate my control circuitry from the high power supply they are switching to protect the controller and ensure the correct power allocation.
The photoelectric coupler looks perfect, but it would be more fun for me to decide to make it myself instead of buying it in an integrated circuit.
Because the price of each chip in my local radiowack is ridiculous, it\'s also cheaper.
However, before we build one, let\'s look at what the optical coupler is actually.
The optical coupler is basically an optical and optical sensor for communication between two circuits.
This is desirable in cases where the load needs to be completely isolated and very fast communication.
Without isolation, a simple transistor will give you fast switching speed.
The relay provides you with the required isolation, but there is not enough switching speed close to fast enough to handle the pulses used to drive the stepping motor.
The optical coupler is the solution because they provide complete isolation and the switching speed is very fast.
My housewife can handle about 300Hz, but the premium families used in the industry can switch at thousand Hz.
In my version, lightis is an LED, the sensor is an optical resistor, and the anda MOSFET transistor switches the actual current through the load. 1 LED-Super-
Smart work is the best.
I use green. Monthly photosensitive resistance type
These are cheap widgets for power transmission in the presence of light.
1 Transistor-
I\'m using 3904 from maize.
Almost any brand will do that. 1 N-
Channel MOSFET transistor-
I used a label on eBay in bulk labeled IRFZ44N.
Two resistors, 10,000 ohms and 100 ohms, respectively.
If your micro-controller supplies more than 5 volts, you should replace the resistance of 470 ohms with a resistance of 100 ohms.
1 small case where ordinary different electrical tape or light does not penetrate this circuit uses the micro controller I/O pinto to control high power loads, such as motors, without the risk of damaging the micro controller sensitive circuit.
How it works: the micro controller switches on the LED.
This causes the resistance of the optical resistor to drop enough to open q1 from the current flowing through the high power.
Q1 then allows the current to flow to the gate of Q2, a high power MOSFET transistor.
This provides a connection to the ground for the load, so the load is turned on.
If your load is a motor or a magnet of any kind, don\'t forget the free-wheeling diode.
This is connected on the load to prevent the magnetic field from breaking things when it is quickly turned on and off.
The 10,000 ohm resistor is to make sure that it reads the logical zero point when Q2 is off.
Without this function, some transistors do not stop conducting when they are turned off.
Please note that although I mark the high power as 5 V, it can be as high as possible without breaking.
I am using this circuit to turn off the motor of the high current 5 v computer power supply.
I would also like to add that although I have designed this circuit myself, I have not invented the optical coupler and there may be many similar solutions.
In order for the optical coupler to work, the LED and the optical resistance must be very close.
They must also be sealed in complete darkness.
This ensures that when the LED is turned off, there will be no light coming to the light resistor, and when the LED is turned on, as much light as possible will reach the light blocker.
I put their faces together and tied them up with black tape.
Make sure the wires of the Assembly do not short together.
Applying glue on the end can help with this, but I am not included and my work is fine.
This is two photocoupler connected side by side on the bread plate.
This is the circuit on the previous page.
The Big Orange wire is the high power positive wire, and the black wire on the right is grounded.
The wire for the load is on the left.
Thanks for watching!