air purifier with variable speed fan and hepa filter - portable air purifier

Whenever the bright sun enters our house through the window, I am always amazed at how many particles I can see floating in the air.
Raising a few furry pets will make the problem more obvious.
Combine it with an allergic wife and you're in trouble.
I could have gone out and spent a lot of money in the store where I bought the air purification system, but where is the fun of that.
I did look at some of the existing off-the-shelf systems, and their controls seem limited in terms of fan speed, usually with only 2 or 3 settings.
What I want is something I can control, from whisper quiet sleep mode to Super Charge mode to make this house clean now.
Using a ready-made clean HEPA filter means I can clean the air well (
A large quotation of 99. 7%)
I can also clean the filter easily if necessary.
If the filter drops in a few years, then I can simply buy another one and insert it directly.
Required parts: 3mm acrylic or plywood 12x30mm female to female M3 gasket 24x16mm Press head bolt 8x120mm PC fan metal finger shield 32 x M5 self tapping PC fan screw 3 x small cable accessories required: 8x120mm PC fan
Good quality, low cost
I have used the 12 V 3A DC PSU 7805 5 v regulator tipnpn transistor for the Arctic PNP fan-
Logic level N-
In fact, the channel FET will be a better Schottky diode
Ideally, with a high current capacity, 1x10 uF electrolytic capacitors 1x5mm uF electrolytic capacitors 10 K potentiometer 100 Green LED 2 x 100nF ceramic capacitors 1x10 uF electrolytic capacitors tools need a laser cutter or table saw, and use SketchUp to drill the soldering iron for PICkit 3 programmers or Arduino programming tools. I created a CAD drawing showing that I integrated everything in
This part took some thought and put everything in and put it in the right place.
I first drew the size of a 120mm fan with 5mm mounting holes and a center hole through which the air passes.
Then copied 3 times and made a square of 240x240mm.
The HEPA filter I use is 240x300mm, so I expanded one of the sizes to allow the entire filter to be installed in plastic.
I added holes through the plastic for the fan cable without hindering the passage of the cable and installed slots for the cable.
Then, I created more space for electronics in another dimension of the original 240x240 square, and then added a 3mm wide cut for the side panel to install.
Finally, I added a cut that allows the HEPA filter to be easily removed or inserted, remove any unwanted lines from the drawing, and make a second copy of the finished part.
The side panels are designed to fit into slots and provide a distance of 30mm between the two acrylic sheets.
On one of the side panels, I am D. C.
Several slots for power outlets, on/off switches, 5mm LED, speed control potentiometer, and cable ties.
Then, laser cut out four pieces of design from a 3mm acrylic sheet. .
Let's start with two large acrylic sheets.
We need to install 4 fans on each sheet.
The first acrylic sheet needs the fan to point inward and the other to point outward, pushing the air onto the filter on one side and pulling the air out of the filter on the other side.
Now, it doesn't matter, it's just that all four fans are mounted in the same direction on the sheets.
Each fan is fixed with two 5mm self-tapping screws in two opposite corners, ensuring that the cable is in the right position to pass through the hole.
Two unused corners are used to connect the finger protection grille to the exposed side of the fan.
Once all four fans are connected to the acrylic sheet and the wires are collected, the cables secure them firmly in the right position.
The wires can then be stripped and connected together.
The wires we are interested in are red and black.
All the Reds need to be together and all the blacks need to be together.
Any other wires can be simply removed.
I also added M3 bolts and M3 threaded gaskets to one of the acrylic products.
Now, both sheets of paper have fans installed and it's time to add electronic components.
Electronic products include the following.
Control the on/off switch of the circuit power supply.
The voltage regulator reduces 12 v to 5 v to power the speed control electronics.
A micro-controller used to perform speed control.
The potentiometer is used to provide the micro-controller with analog inputs for controlling the fan speed.
The transistor is used to switch the 12 v power supply to the motor.
I used a small portion of the veroboard to connect the components together.
I made the schematic of the circuit I want to make.
Then, with some ideas of trying and reducing the workload, the circuit was laid on the veroboard.
DC sockets, potentiometer, LED and on/off switches are added to smaller acrylic components, mounting holes and wires are connected to the veroboard circuit and cables are fixed in place.
The diode in the motor drive circuit is used to prevent the back potential (
High voltage spikes generated by rotating motor and or high frequency PWM control)
From back to the micro controller and causing damage.
Make sure you have diodes installed to help ensure the system works for a long time.
Once the micro-controller is programmed with its firmware, we can test all the work before the assembly is complete.
The firmware is written in Flowcode and is very simple.
We read the analog voltage from the analog pin connected to the potentiometer and convert it to a digital value.
The value then sets the marking/spacing ratio of the pulse width modulation output pin that drives the control transistor base.
Add a small delay and a loop and we're done.
The configuration settings of the 16F88 device are shown in the figure, internal osc, internal MCLR, watchdog is on.
If you're using Arduino and don't want to use Flowcode, then just find one of the many Arduino PWM tutorials and you'll be able to get up and running quickly.
Make sure to connect the two signals to the Arduino pin with the required functionality: 1-
Analog Input and 2-PWM output.
Now, when the sun is shining, I can simply enjoy the light and heat without the fear of staring at the Air suspended pellet swamp of everything around me.
My wife can't even sneeze.
Unfortunately, the filter unit I purchased is not the size specified on the website.
It's getting smaller and wider, which gives me the problem of installing it.
I fit it by installing it slightly diagonally and removing the two support thread gaskets.
It works fine, but it is not easy to remove and clean the filter.
So I would suggest buying the filter first and then designing it according to your own size to make sure it fits.
Here are some photos of the finished unit.
Why don't you go by yourself?
Thanks for watching.