New Gadget project started. Fridge fan controller. (1 Viewer)

Dec 10, 2013
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Why regret it, if you've done production engineering, you'll have quite a good electrical knowledge anyway. You must be fully versed in explaining to the shift sparky what the electrical fault is that's caused the breakdown, as you know they won't leave their coffee or get out of their chair at all if there's the slightest, most remote possibility that it could maybe be MECHANICAL :eek::eek::eek::eek:

Been there.:rolleyes:
 
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Gromett
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Been there.:rolleyes:
Me too but on the other side of the bench :p I wouldn't touch anything with water in it, plumbers wouldn't touch anything with sparks in it. Quite a few standoffs when I worked at Rampton especially with the Shit pot masher :p


I will be providing full instructions on all parts of it and will be happy to answer any questions. The only stumbling block might be the fact I am on Linux not windows so won't be able to provide detailed answers on how to install any drivers for the programmer.

All the dev and progammer software I am using is free and open source, the hardware I am using is open source so really there is nothing stopping anyone from doing what I am going to do :D

If you can figure out how to use a soldering iron the rest will be straight forward.(y)
 
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You don't need Linux, it is just another operating system like windows or Mac OS/X. I use Linux so won't be able to advise you on anything specific to Windows.

Here is a quick run down of what happens.

I will create the circuit board on a breadboard like this.
breadboard.jpg
this will be connected to the arduino Uno board I will use to develop the software. The programming environment is a free download from here.
https://www.arduino.cc/en/Main/Software

Once I have confirmed this prototype works using the Uno board I will take a bare microprocessor and create a simple programmer.
I will use the Uno to program the ATTiny85 bare chips.

The great thing about the Atmel chips is that they don't require any external components. Simply give them a power source and they work.

The way to program them is via what is call an ISP In System Programmer which is a simple USB to serial programmer. Or you can using an existing Arduino to do the programming.

The method I will use is this one.
https://www.arduino.cc/en/Tutorial/ArduinoToBreadboard

Although I will modify it to work with the ATTiny85 rather than the ATMega328.

The ATMega is a 28 pin chip that has 32Kb of memory. This is too much memory and too many IO pins for this job. So I will be using the ATTiny85 which is an 8 pin chip and has 8Kb of memory and 5 IO ports.

If you want to program your own, and be able to update it if I improve the software at a later date you will either need to build your own ATMega for about £3-4 + buy an ICMP programmer. Or buy an UNO which ranges in price from £5-10..

If I am going to be programming chips for people I will probably also need to put small kits together as well. I will have to think about that though.

All the above sounds complicated, but I will walk through each part step by step and give a few other options such as using a dedicated programmer like this
http://www.ebay.co.uk/itm/141882193319 which is only 99p but is fairly limited. Or to buy a digispark like this

The problem with the digispark from my point of view is that you would need to provide a USB power source behind the fridge. However this would make the programming of the chip much easier for you.

Anyway, more details to come once I have the main parts arrive hopefully Wed or Thu this week.

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Apr 27, 2016
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to light the floor so I can see my way to the loo without switching the main lights on and ruining my sleep by waking me up too much.
Can I suggest you use red LEDs. When your eyes are dark-adapted at night, even a short burst of white, green or blue light will ruin the dark adaptation. Red light does not. I find this fact is well known to people like the military or astronomers, but many others have never heard of it. Don't take my word for it, try it yourself, it's simple.
 
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Gromett
Feb 27, 2011
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Can I suggest you use red LEDs. When your eyes are dark-adapted at night, even a short burst of white, green or blue light will ruin the dark adaptation. Red light does not. I find this fact is well known to people like the military or astronomers, but many others have never heard of it. Don't take my word for it, try it yourself, it's simple.
Thanks, I am aware of that as we tried using red lights when ratting. but the problem with red light is that it doesn't give enough illuminating at low levels so you need to boost it quite high. For map reading, loading weapons etc etc it is great. but for illuminating your way not so much. For my situation I will be happy with white light at very low levels. but others are free to use red led's in their install :D
 

JJ

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All the dev and progammer software I am using is free and open source, the hardware I am using is open source so really there is nothing stopping anyone from doing what I am going to do

If this is the case, I will knock out a couple of the devices before brekky tomorrow...

JJ :cool:

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Gromett
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If this is the case, I will knock out a couple of the devices before brekky tomorrow...

JJ :cool:
Might be a nice little sideline for you JJ knocking them up for people :p
 
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Gromett
Feb 27, 2011
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You know the Chinese parts will arrive the day before the EBay ones don't you? :LOL:
10 packages arrived today :D
I can't keep taking trips over so will wait for wed/thu before going over for them. But sounds like about half of the deliveries have now arrived.
 
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Feb 27, 2011
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I got a bit curious as to what is involved in commercially producing a PCB using surface mount etc etc. This video might be interesting to some of you. Gets better further in.



About about my history. I did electronics at college and have designed, manufactured and assembled my own PCB's in the 80's when everything was through hole mounted. I wanted to see what was involved in commercially producing surface mount boards. This has definitely confirmed I will not be making these for people. There is too high a risk of me making a minor error and losing all the money involved in doing it.

My designs will all use what is called vero board or prototyping board which are perfectly fine for one offs and small quantities and are easy for amateurs to make and test. It will be all through hole mounted components to keep soldering easy and the only tools you will need are;

Soldering iron,
Small Drill bit (to cut tracks)
hack saw and file if you want it to be as small as possible and neat.

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This is the type of prototyping board I will be using.
 
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Gromett
Feb 27, 2011
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Decided to look for a circuit design/PCB design package. As usual I just looked in my Linux repository and first up was Kicad.

http://kicad-pcb.org/

I have had a bit of a play and it seems fairly comprehensive and will be up to the job I need it for. I was going to hand write my circuit design and take a photo to post on here. Very amateurish and I thought I should be able to do better... I won't be putting a great deal of time into this package but it should allow me to do fairly decent looking circuit diagrams for everyone to follow rather than photo's out of my notebook.

Just thought I would post this video to give you a taste of Dave's style.

 
May 29, 2013
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Just read thro your fan project. Does your fridge have a certain ambient temp at which it doesn't do the job anymore ? We were in France in Aug at 33c in the shade and the fridge kept everything cold and frozen as required. Mind we kept the vents in the shade.

I was also wondering how you will define if the job has made a difference to the fridge in terms of keeping cold ? Presumably you'd have to log the temperature in the fridge for a full day at a certain ambient temp. with no fans running, and not opening the fridge door, then log the fridge temp. on a day with the same ambient temp. with the system running and see if the temperature of the fridge is significantly lower.

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Feb 27, 2011
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Just read thro your fan project. Does your fridge have a certain ambient temp at which it doesn't do the job anymore ? We were in France in Aug at 33c in the shade and the fridge kept everything cold and frozen as required. Mind we kept the vents in the shade.

I was also wondering how you will define if the job has made a difference to the fridge in terms of keeping cold ? Presumably you'd have to log the temperature in the fridge for a full day at a certain ambient temp. with no fans running, and not opening the fridge door, then log the fridge temp. on a day with the same ambient temp. with the system running and see if the temperature of the fridge is significantly lower.

No serious problems, this is about efficiency. I have a new compressor fridge coming in about 6 weeks and I want it to operate using the least possible amount of electric and to keep the operations cycle as short as possible. I have been inside the vents of a fridge a number of times and they always seem to trap heat in that area. I added a fan to the fridge on my previous van and it definitely made a difference to it's efficiency.

If yours works fine and you don't want to add a fan then this project is not for you :p Quite a few of us on here have used fans in the past or use fans now with good effect.
Lots of places now sell these fans so it is not just me who has found them to be effective. I just have particular requirements for them.
 
May 29, 2013
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No worries, just wondered how you know the fan is improving efficiency ? Without before and after measurements of fridge temperature, then your just going by feelings surely ?

I presume your fridge, when your parked up, is either running on mains hook up, then who cares about how much mains power your using, or on gas, which obviously is a cost to you, but very difficult to measure actual gas usage from the tank, before and after.
 
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Gromett
Feb 27, 2011
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No worries, just wondered how you know the fan is improving efficiency ? Without before and after measurements of fridge temperature, then your just going by feelings surely ?

I presume your fridge, when your parked up, is either running on mains hook up, then who cares about how much mains power your using, or on gas, which obviously is a cost to you, but very difficult to measure actual gas usage from the tank, before and after.

My beer was colder when the fan was operating, when I was in France.

That aside. It is obvious that is will be more efficient/effective. If you are clearing out the heated air quicker the fridge doesn't need to work so hard.

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On the Subject of Open Source Hardware. This story just came to my attention.

It is slightly technical. But the interesting part is about Apple and the OCP project. The OCP project is an open source hardware project to make data centres cheaper and more reliable. Rather than companies designed stuff and keeping it to themselves they contribute their developments to the OCP project.

Apple network engineers developed a 100% reliable network system and they wanted to contribute it to the OCP. Apple refused so they all left. The entire team quit because Apple wouldn't open source their design :D Well done guys.

Even if you don't understand every word you will understand the philosophy and the impact it is having.

http://uk.businessinsider.com/faceb...ple-networking-team-to-quit-2016-10?r=US&IR=T

Basically I can go to a contract manufacturer and buy any of these products at a fraction of the price I can from HP, Cisco etc etc. Better products at lower costs. Giving away stuff benefits everyone which is what opensource is all about.
 
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Took longer than expected to get my exhaust replaced today so the next trip to get parts won't be till Sunday. I was hoping to go today once my exhaust was fixed but.... :(

Oh well, should have all the parts by sunday now. sorry for the delays everyone. One of the downsides of being a fulltimer.
 
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Just had an amazon gift card given to me by a grateful client. Just splurged on a load of components for my stores.

50 Pcs 6x6x5mm 4-Pin DIP Through Hole Momentary Tactile Push Button Switch -
20PCS Photoresistor GL5528 LDR Photo Resistors Light-Dependent -
Ranking MB102 Breadboard 3.3V/5V Power Supply Module 3.3V/5V For Arduino Board -
sourcingmap 50 Pcs 5mm Round Head Common Cathode RGB Light LED Emitting Diodes -
SODIAL(R) Keypad Shield Board Blue Backlight for Arduino Robot LCD 1602 1280 2560 UNO US - .
LAOMAO 5 pairs Infrared Diode LED IR Emission and Receiver -
HC-SR04 Ultrasonic Distance Rangefinder/Obstacle Detection Module Blue -
TaylorRoco IIC Serial 128X64 Replacement Display Module For Arduino Conditional Access Modules -
150 x 3mm Red Green Yellow 2 Pin LED Light Emitting Diodes -
Arduino Uno Case Enclosure Transparent (Blue) -
Generic 50 Values Ceramic Disc Capacitors Assorted Kit (Pack of 1000pcs) -

Some of these items have caused me to think of some new ideas for later projects.

The Ultrasonic distance rangefinder and the Colour LEDs for instance. I had a friend who had to reverse his van onto his drive and up against a car parked on his drive.
It is a works van so fitting reversing sensors or camera is not possible. The car doesn't always go in the same place. He needs a big enough gap to get the back doors of the van open but needs to get far enough on the drive so as not to block the footpath. He always overhangs just a little and he brings different vans home from work depending on what job he was on that day.

I am thinking of having an ultrasonic sensor on a post which he can place at the front of the car. This will have an arm on it with 3 coloured LED. Red, Green and Yellow.
The Green one will be on when he is too far away. The yellow one will flash faster and faster as he gets closer. The red comes on when it is times to stop. The LED arm will be visible in his mirrors.

This will be a dead simple project, but thought it might be of interest to some on here who also have to reverse onto their drive? It is only my list of projects to do but at the end of the list.

I could also make it wireless so that he could have the LED panel inside the van.

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Apr 27, 2016
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I want to use a compass, GPS and real time clock to figure out where the sun is in the sky and using 2 stepper motors to point a tiny solar panel at it.
That's what you need for an installation in a building, where you can install it level and it won't move. An MH will of course not be very level. So maybe the addition of an accelerometer to measure the slope would be useful. Feed it to a display to make it into a very useful level meter. Also the compass display would be good to decide the best parking direction on a cloudy day or if you arrive at your pitch after sunset.
 
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Just had an amazon gift card given to me by a grateful client. Just splurged on a load of components for my stores.

50 Pcs 6x6x5mm 4-Pin DIP Through Hole Momentary Tactile Push Button Switch -
20PCS Photoresistor GL5528 LDR Photo Resistors Light-Dependent -
Ranking MB102 Breadboard 3.3V/5V Power Supply Module 3.3V/5V For Arduino Board -
sourcingmap 50 Pcs 5mm Round Head Common Cathode RGB Light LED Emitting Diodes -
SODIAL(R) Keypad Shield Board Blue Backlight for Arduino Robot LCD 1602 1280 2560 UNO US - .
LAOMAO 5 pairs Infrared Diode LED IR Emission and Receiver -
HC-SR04 Ultrasonic Distance Rangefinder/Obstacle Detection Module Blue -
TaylorRoco IIC Serial 128X64 Replacement Display Module For Arduino Conditional Access Modules -
150 x 3mm Red Green Yellow 2 Pin LED Light Emitting Diodes -
Arduino Uno Case Enclosure Transparent (Blue) -
Generic 50 Values Ceramic Disc Capacitors Assorted Kit (Pack of 1000pcs) -

Some of these items have caused me to think of some new ideas for later projects.

The Ultrasonic distance rangefinder and the Colour LEDs for instance. I had a friend who had to reverse his van onto his drive and up against a car parked on his drive.
It is a works van so fitting reversing sensors or camera is not possible. The car doesn't always go in the same place. He needs a big enough gap to get the back doors of the van open but needs to get far enough on the drive so as not to block the footpath. He always overhangs just a little and he brings different vans home from work depending on what job he was on that day.

I am thinking of having an ultrasonic sensor on a post which he can place at the front of the car. This will have an arm on it with 3 coloured LED. Red, Green and Yellow.
The Green one will be on when he is too far away. The yellow one will flash faster and faster as he gets closer. The red comes on when it is times to stop. The LED arm will be visible in his mirrors.

This will be a dead simple project, but thought it might be of interest to some on here who also have to reverse onto their drive? It is only my list of projects to do but at the end of the list.

I could also make it wireless so that he could have the LED panel inside the van.
Beats a tennis ball on a string hands down (y)(y).
 
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That's what you need for an installation in a building, where you can install it level and it won't move. An MH will of course not be very level. So maybe the addition of an accelerometer to measure the slope would be useful. Feed it to a display to make it into a very useful level meter. Also the compass display would be good to decide the best parking direction on a cloudy day or if you arrive at your pitch after sunset.

I am not doing that particular project for a practical application. I am interested in the maths involved. The only way to test my maths out is to do it. I will be using a tiny polymorphic hobby panel to test it with which won't be mounted on the roof. That said you did raise a very interesting point and I may have to consider that when I get onto that project :)
 
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I have started work on the project finally.

Here is the first draft of the circuit diagram. This doesn't include the temp sensors yet as I am concentrating on getting the fan control correct first.

I will write up some notes with calcs etc later.
circuit-1.png

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Also here is a handy cheat sheet for the ATTiny85/Arduino.

The arduino software assigns numbers to I/O ports that don't match the actual pin numbers on the chips. So this is useful for converting electronic pin numbers, to software arduino I/O number.
 

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Updated Circuit diagram.
I hadn't separated the supply.
circuit-1.png
 
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A few quick notes.

I am modifying the design I will release publicly to use the sparkfun dev board to make things easy if you want to do this yourself.

sparkfun.png


As you can see this comes in the format of a USB thumb drive with the P0-P5 IO broken out to through holes.

What this means is you can plug it into your USB port and program it yourself using free software from arduino. Don't panic just yet I will hand hold you through that bit.

The upside to this is that I don't need to ship anything and you can reprogram it if we make any improvements to the software over time.

The downside is I lose 2 IO pins to the USB communications and I lose another pin because it has a built in LED with limiter resistor on pin 6. So out of 5 IO pins we lose 3.

Luckily I can work around this by putting both temperature sensors on the same IO pin. The final PWM pin will be used to control the fan.

So far we are up to 4 main components on the circuit plus 2 temperature sensors. So it will be a very simple circuit to make and a simple soldering iron, snips and 3mm drill bit should be all you need to make this.

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