Transform Basic Bathroom Fan to Advanced

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Introduction: Transform Basic Bathroom Fan to Advanced

This is my first instructable !!

After i moving with my girlfriend into our new rent house, our new bathroom is equipped of a fan evacuator with a PIR sensor to evacuate humidity, every time we switched ON the light of the bathroom, the FAN switch ON and made a lot of noise !!

I like every time my girlfirend goes to bathroom at night ...

Requirements:

FAN would be power ON if the humidity is higher than 75%

OR

The door is closed (go for a dump)

Step 1: What Inside This Silent Fan ?

+ No transformator => Problem: i cannot extract safe 5V out of the box.

+ No Relay.

Step 2: Add Switch With Snubber Filter

I choosen to drive the FAN with dual relay with optocoupler input protection, the easy way to drive any thing from a µC

I'm very lucky that this dual relay go inside (i cut a litle bit the eges to fit it perfectly)

snubber filter :

Every time the relayes are cut off, one phenomenon is produced:

> µc reset alone.

The snubber filter (Capacitor in serial with Resistor) is wired in parallel with the FAN.

From Wiki:

Snubbers are frequently used in electrical systems with an inductive load where the sudden interruption of current flow leads to a sharp rise in voltage across the current switching device, in accordance with Faraday's law. This transient can be a source ofelectromagnetic interference (EMI) in other circuits.

Step 3: Add 5V Power Supply

I recovered an old LG Cell Phone charger to use as a power supply (230V => 5V 0.5A)

Step 4: Remaining Space

Take measures of remaining space where the PCB will be placed.

Step 5: Cut Useless Brace

I cutted useless brace to win a little bit more spaces.

Step 6: Schematic Μc/Sensor

I chose the Atmega 328p because I had several at home ^^

AM2302: The hygrometer/temperature sensor (1-wire bus)

Step 7: LED Driver

NPN Transistors working in saturation mode drived by µc.

Step 8: Door Detection

Infrared Proximity Sensor was built with an TCRT5000 and a LM324, the LM324 is aop used as a voltage comparator.

When the infrared light (from the IR LED) reflect a surface (bathroom door), the phototransistor leave the current to flow, The input 5 of LM324 is at +IRV and compare the voltage with the input 6 (bridge voltage divider), if the value is higher, the output 7 give 3.5V (5V - 1.5V).

N.B. IRV depend the amount of infrared light coming back to to IR receiver

Step 9: Lets Go to Disign the PCB

I designed the PCB with Fritzing and took into account the space available in the box.

Step 10: Test and Reshape the PCB

I reshape the PCB to avoid useful brace.

Step 11: Let's Go to Solder Components

When i soldered the components, I realized that I forgoten to place the Quartz ! ... I improvised by soldered it above the µc.

I test with 5V power supply, I held my breath before I switched it ON ... poiouff, this time, all work fine for first time.

RED light: No communication with hygrometer sensor.

GREEN light: humidity < 75%

BLUE light >= 75%

N.B. All light color are bliking to say me, "i'am alive"

Step 12: Test FAN Drived by Μc + Close the Case

Everything seems fit perfectly

Step 13: Mount the Proximity Sensor Near the Door

I made a hole on the ceiling for passing the wires.

Step 14: Final Test

After calibrated the poximity sensor (set the potentiometer to detect the door presence)

While i took my shower, i noticed that the sensor takes a long time before it detect moisture > 75% ... may be i must move the AM2302 near the hole where come the power.

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    22 Comments

    0
    alcurb
    alcurb

    7 years ago on Introduction

    It's a fun solution for those who love prototyping circuits. Your issue with the humidity sensor could be addressed by cutting a large enough hole on the fan case to expose the humidity sensor to the ambient air. There is a reason why the sensor has many holes. I bet that would improve the response time greatly.

    That said, I find that an alternate solution would be to mount the motor on soft rubber washers or shocks. It's to reduce the transfer of noise to the case.

    That however doesn't address the fan coming on the whole time the light is on because one switch controls both light and fan. A solution I had explored is to buy one of those remote control switches (transmitter) that look like a wall switch and stick it next to the the light switch. If the receiver end doesn't fit inside the fan case, the receiver assembly can be taken out of it's own enclosure and placed inside the fan case. It's a neat solution and the receiver doesn't care about inductive or resistive loads because the receiver has a mechanical relay. I tried to implement that idea on my exhaust fan, but the enclosure for the fan is very tight around the fan itself, way too small to fit anything else in there, and it's in an old rental apartment.

    0
    neo_xnitro
    neo_xnitro

    Reply 7 years ago on Introduction

    Yes, you are right, but i prefer move the sensor near the existing hole (high above) to avoid as much as possible moisture inside the fan case.

    0
    pedrobedro
    pedrobedro

    Reply 7 years ago on Introduction

    You would only see it if you lived in the bathroom :D

    0
    BFB53
    BFB53

    7 years ago on Introduction

    I am curious why not just put a switch on the ac line next to light switch to allow it to be turned on and off independent of light seems like a lot of work not mention cost when a single double switch would have done the job would not have even had to install a new handy box just wire. or even a remote ir switch. Oh well very neat job and well laid out. Just feel its over kill.

    0
    neo_xnitro
    neo_xnitro

    Reply 7 years ago on Introduction

    $1.90 2 Channel Relay Module With optocoupler

    $1.03 TCRT5000 Reflective Photoelectric Switch Infrared

    $0.99 Ultra-Bright 4 pin RGB Diffused Common Anode LED

    $0.99 NPN Transistor TO-92 2N2222

    $1.08 LM324N

    $3.40 AM2302 Digital Temperature And Humidity Sensor

    $1.75 ATMEGA328P

    x resistors

    x capacitors

    x PCB

    x wires

    ... the FAN belongs to the owner

    Total: 11.14 $

    0
    tovey
    tovey

    Reply 7 years ago on Introduction

    There's this thing called building codes.

    In some locals, the light and fan must be connected to the same switch.

    0
    oz5es
    oz5es

    7 years ago on Step 11

    I hope You're not welding it, rather than soldering, hi. ;-)

    Nice work, I will save it for later.

    0
    mikeely
    mikeely

    7 years ago

    Very cool instructable! Way above my abilities but it's something that I would enjoy having and now I have an idea how to do it. Well done!

    0
    interzoneboy
    interzoneboy

    7 years ago on Introduction

    This is exactly the sort of project I love to see on here... Hacking an everyday thing that everyone has and uses, and making an ordinary thing awesome. Great work! Thank you for sharing.

    0
    frankie2234.
    frankie2234.

    7 years ago on Introduction

    If you buy Panasonic, there brand is extremely quiet. You can't hear it running while your next to it.

    0
    rivertennisdog
    rivertennisdog

    7 years ago

    Very important to have a fan with some noise if you ever have guests; I don't want to hear what's going on in there, and most people don't want to be heard. Some fans even offer a noise option.

    0
    tomatoskins
    tomatoskins

    7 years ago on Introduction

    This is awesome! I love simplifying my life with things like this.