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

[Riverbankannie]

Do you know what...this is all completely over my head but strangely addictive. Like a detective novel somehow. It's a page turner and I cannot wait until the end!
Loving all the patient explanations @Gromett

 

[DBK]

Do you know what...this is all completely over my head but strangely addictive. Like a detective novel somehow. It's a page turner and I cannot wait until the end!
Loving all the patient explanations @Gromett

Someone needs to start a.........wait for it........fan club.

 

[Gromett]

I think as @Birtha & @John Laidler have already attempted to point out it is the 30º ambient that is the factor. Above that you have loss of condensing on an absorption fridge. Even on domestic compressor fridges the condenser & fan have different ratings for the same unit depending on which country it is specified for. A Uk one used to be around 30º whereas a Southern Mediteranean one would have a figure of 37º at least. I have just checked mine & the fans are running at full speed with a 16º differential .. i look forward to seeing how well it performs.

I will try one last time to try and explain my goal here.

I am not trying to fix a flaw in the fridge or improve it's design. Anyone who has taken off the top vent of their fridge will know that even with the 2 vents there is a lot of trapped very warm air inside. As has been proven by a number of people on here having a fan operating to assist in the air flow improves the efficiency of the fridge.

The easiest way to do this is to simply have one or more fans going full tilt all the time.

This solution is no good for me as I cannot stand the noise of fans and my hearing is particularly sensitive to it.

So. I want a fan that will operate at the lowest speed to have the most effect in operation. I am not trying to improve the efficiency of the fridge itself, just the movement of air behind the fridge.

A temperature sensor at the bottom of the fridge near the lower vent will measure the ambient temperature. Another sensor near the top vent will measure the fridge cavity temperature. If there is a difference between these two temperatures it means that convection is not effectively taking place. If there is zero temperature difference then either the fridge is not operating or convection alone is sufficient. The bigger the difference in the temperature the faster the fans will go.

It is a really basic idea. I have a few tweaks to add to it such as switching off at lower ambient temps etc.

^{_{Subscribers  do not see these advertisements}}

 

[Gromett]

Just had an email confirming that some more parts have arrived. Will be driving over at lunch tomorrow to collect. I am getting excited now

 

[dave newell]

I don't claim to understand the tech detail of the stuff you're using (although I'm sure I could learn it if I could be bothered) but I do understand your goal and the logic of how you are approaching it. I follow this thread with anticipation.

D.

 

[Reallyretired]

How are you going to adjust for the winter? In winter temperatures there will be a big differential between the top and bottom vents but the fans will not be required.

A simple on off switch would do I suppose (in fact that's all mine has) so turn it off in the winter, but probably not an elegant enough solution for you.

The switch also prevents the fan running on warm nights while trying to sleep.

^{_{Subscribers  do not see these advertisements}}

 

[Gromett]

How are you going to adjust for the winter? In winter temperatures there will be a big differential between the top and bottom vents but the fans will not be required.

A simple on off switch would do I suppose (in fact that's all mine has) so turn it off in the winter, but probably not an elegant enough solution for you.

The switch also prevents the fan running on warm nights while trying to sleep.

I am setting it to detect when the temp falls below a certain level and turn the fans off automatically.

It won't have a switch in my install as that is the point of it. I want it to be fully automatic.

 

[Gromett]

I was just about to prep the van for driving over the Lincolnshire wolds to get the parts. The skies have just opened. I don't fancy emptying casettes and grey in this weather never mind wading through the rivers that the Small Wolds roads become in this weather. Might have to delay collecting parts till tomorrow Bugger

 

[andy63]

My kind of read... even if I do get a bit lot in the detail..
Looking forward to outcome and hope it's successful. .
Andy.

^{_{Subscribers  do not see these advertisements}}

 

[TheCaller]

The skies have just opened.

It's stopped now & you've got until 3pm before the next lot arrives. Tomorrow doesn't look much better. We're all waiting with baited breath, so off you go!

 

[Gromett]

It's stopped now & you've got until 3pm before the next lot arrives. Tomorrow doesn't look much better. We're all waiting with baited breath, so off you go!

Just been across, 4 packages, all excited to open them to find out what bits I have.
2 bloody USB cables in separate packets from the same supplier.
1 Sim card (not much help for this project)
10 IRL540N mosfets. Without the diodes not much use

So still waiting for the next batch.
Still to arrive.

328pcs 2:1 Polyolefin Halogen-Free Heat Shrink Tube Sleeving 5 Color 8 Size £2.90
5 x dc adjustable PSU £2.77
10 x DS18B20 – 1 wire temp sensors £7.68
3 X DHT11 temp/humidity sensors £3.22
1 X wire snips £2.15
1 X HC-05 bluetooth £3.83
200 X Electrolytic Capacitors £4.49
40 X male to male jump leaders £1.58
40 X male to female jump leads £1.74
40 X Female to female jump leaders £1.58
300 X Zener Diodes £2.64
100 X diodes £2.08

10 X reed switches £1.87

10 X ATTiny85 chips £9.78
1 X ATTINY85 Dev board £0.99
1 X ACS712 30 Amp current sensor £1.39
1 x Atmel ATMEGA328P-PU AVR preloaded with Arduino UNO bootloader +16Mhz +2x 22pF £3.75
3 x Atmel ATMEGA328P-PU AVR bare chips £2.20
1 x Universal, ZIF Type IC Socket 28 PIN (0.3") DIP

 

[Gromett]

Got paid for a job so Just ordered some more bits...

3 pin fan headers. So I can just plug the fans onto the dev board without having to chop the connectors off and solder them to the board.
100's of header pins and female sockets. I don't want to solder directly to my displays etc.
1 meter of 40 way ribbon cable so I don't have loads of individual cables floating around while developing.

^{_{Subscribers  do not see these advertisements}}

 

[Gromett]

Thought some of you might find this interesting. Julian does some great videos and I have been following him for a few years. His MPPT project is particularly interesting for me. In this video he explains the difference between a synchronous and asynchronous buck dc-dc down converter along with an explanation why linear regulators are bad.

He also destroys a buck converter board to see what is inside a particularly juicy Inductor...

 

[Gromett]

While I am waiting for the rest of the parts to arrive I thought I would let you know what the other projects I have in mind after this one is done.

1) Central Controller.
2) Van Battery monitor.
3) Hab Battery monitor++
4) Water Level
5) Temperature monitor (3 locations)
6) Night light
7) Sun tracker.

Details.

Central Controller.
This will be an arduino Mega that reads sensors and monitors. It will have a 4 line 20 character display but will also be linked to my phone/tablet via blue tooth.
Future projects will link into it. This is really going to be the central controller in my van.

Van Battery Monitor.
The van battery monitor will monitor the voltage of the van battery. This will be readable via bluetooth on my phone and also via my central controller.
It will send me an alert if the van battery drops below 12.2V notifying me to get it on charge before it falls below a level where it won't start my van any more.

Hab Battery monitor++
This is a total package. It will monitor the incoming/outgoing current and use coulomb counting to keep track of the charge state. In addition it will monitor the current from my solar panel, solar charge controller and B2B charger.
It will also monitor the voltage on the input and output to my solar charge controller. It will display input watts, output watts of the solar charger controller along with efficiency. The main users of electricity will also have current monitors in them. For instance the fridge, light circuit and boiler.

All readings will be logged using for usage tracking.

Water level.
I have an idea on how to monitor the level in my fresh water tank using some rare earth magnets, some reed switches and some resistors. Lined into an arduino and a bluetooth module to report to my phone and central controller.

Temperature monitor.
I want to have an accurate temp sensor with logging that will log the outside temp, inside temp and boiler cabinet temp. It will alert me if the boiler area temp falls below 4C.

Night light.
This is more a toy than anything. I will place low power led lights at close to floor level. They will switch on automatically when I move near them 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. Might be useful for those of you who don't travel solo so you don't wake the other person up.

Sun tracker.
This is going to be a really fun project for me. 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.
It will adjust the panel once an hour or once every half hour. I want to do all the maths to calculate sunrise and sunset and point the panel accurately without using light sensors at all. This is going to be a real learning experience for me as my first glance at the maths made me take a seriously deep breath. A very nice challenge and I have to fit it into 32K of memory. I will not only have to re-learn all my trigonometry but learn some solar mechanics as well. Looking forward to this one.


If you have any suggestions for other projects please let me know. No promises but if I find it interesting or it might be useful for me I may add it to my project list.

 

[stevec]

Good luck with the compass in a metal van. It will need to be "swung" to calibrate it and minimise errors. But probably good enough to get a best estimate position. Tracker can be fine tuned later with optical sensors.

What happened about the gas level sensor?

^{_{Subscribers  do not see these advertisements}}

 

[Gromett]

Good luck with the compass in a metal van. It will need to be "swung" to calibrate it and minimise errors. But probably good enough to get a best estimate position. Tracker can be fine tuned later with optical sensors.

What happened about the gas level sensor?

It won't be for use in a van. I have no actual use for it. It is a fun project and I will open source the code. I am interested in the programming specifically I want to see if I can accurately point at the sun at sunrise and sunset and track through the day using pure maths.. That is why the project is last on my list as it is the least useful to me personally.

The gas level sensor is on the back burner as I may be going for an under slung tank early next year.

 

[OldAgeTravellers]

Hab Battery monitor++

This will be interesting to me. I was working on the van the other day and put the fridge on to 12volt to give a large drain to see what the panels were doing and forgot to turn it off which took the batteries down overnight till the EBL switched them off. Unfortunately I think it has killed or seriously damaged them. Strange that this van allows 12volt use without the +D or +S signals, Dometic again!!
So a text to say they were low would be good. I suspect it will need the Central Controller as well though.
Steve

 

[Gromett]

This will be interesting to me. I was working on the van the other day and put the fridge on to 12volt to give a large drain to see what the panels were doing and forgot to turn it off which took the batteries down overnight till the EBL switched them off. Unfortunately I think it has killed or seriously damaged them. Strange that this van allows 12volt use without the +D or +S signals, Dometic again!!
So a text to say they were low would be good. I suspect it will need the Central Controller as well though.
Steve

The central controller is simply an Atmel ATMega328P which costs less than £1. and a few 1p components. I will be adding a 3G modem, bluetooth modem and an LCD display to mine. Probably less than £15 all in...

^{_{Subscribers  do not see these advertisements}}

 

[OldAgeTravellers]

The central controller is simply an Atmel ATMega328P which costs less than £1. and a few 1p components. I will be adding a 3G modem, bluetooth modem and an LCD display to mine. Probably less than £15 all in...

Well worth it to protect £200 worth of batteries. Either that or I need a new brain. Your project sounds easier.
Steve

 

[Gromett]

Well worth it to protect £200 worth of batteries. Either that or I need a new brain. Your project sounds easier.
Steve

If you want to build your own board then there are dirt cheap suppliers for all the parts.
For example.
www.ebay.co.uk/itm/121608734916 (£3.75)

Or you can buy a full board but it includes things like the programmer, connectors, regulators etc etc etc.
Link Removed (£7.29)

I bought my full board from Amazon though for £10.00 as I wanted a quick return option if it was faulty.
http://amzn.to/2dVa0eV

If you buy a full board ensure you buy one with a socketed chip. That way if you screw up you only have to spend £1 to get a replacement rather than the full £10 for the board.

 

[Riverbankannie]

For those interested here is a list of the parts, link and price.
ATTiny85 Microcontroller. £0.98 each.
Link Removed. £0.99 each
Broken Link Removed. £0.79 each (£1.58)

The rest of the components cost less than 1p each.
Diode, I bought a pack of 100 for £2.08
Resistors I bought a pack of 1460 for £7.08

So all told it will be less than £4 in parts.

Just been across, 4 packages, all excited to open them to find out what bits I have.
2 bloody USB cables in separate packets from the same supplier.
1 Sim card (not much help for this project)
10 IRL540N mosfets. Without the diodes not much use

So still waiting for the next batch.
Still to arrive.

328pcs 2:1 Polyolefin Halogen-Free Heat Shrink Tube Sleeving 5 Color 8 Size £2.90
5 x dc adjustable PSU £2.77
10 x DS18B20 – 1 wire temp sensors £7.68
3 X DHT11 temp/humidity sensors £3.22
1 X wire snips £2.15
1 X HC-05 bluetooth £3.83
200 X Electrolytic Capacitors £4.49
40 X male to male jump leaders £1.58
40 X male to female jump leads £1.74
40 X Female to female jump leaders £1.58
300 X Zener Diodes £2.64
100 X diodes £2.08

10 X reed switches £1.87

10 X ATTiny85 chips £9.78
1 X ATTINY85 Dev board £0.99
1 X ACS712 30 Amp current sensor £1.39
1 x Atmel ATMEGA328P-PU AVR preloaded with Arduino UNO bootloader +16Mhz +2x 22pF £3.75
3 x Atmel ATMEGA328P-PU AVR bare chips £2.20
1 x Universal, ZIF Type IC Socket 28 PIN (0.3") DIP

What happened to your original £4 fan project, have I missed something, are you on to your new projects @Gromett ?

For those interested here is a list of the parts, link and price..........

So all told it will be less than £4 in parts.

^{_{Subscribers  do not see these advertisements}}

 

[Gromett]

What happened to your original £4 fan project, have I missed something, are you on to your new projects @Gromett ?

It is still on, I am just waiting for the parts to arrive. One of the downside of ordering dirt cheap parts from China is that they can take up to 30 days to arrive

I can't do anything till the temperature sensors, capacitors and the diodes arrive. The rest of the parts are not essential but those two are.

 

[Xabia]

Very interested in your idea of a night light system. Would you use individual lights spaced along the way from bed to toilet or one continuous strip? Any idea where I could buy the low power LED's and the movement sensor please? Would save the other half having to use a torch.

 

[Gromett]

Very interested in your idea of a night light system. Would you use individual lights spaced along the way from bed to toilet or one continuous strip? Any idea where I could buy the low power LED's and the movement sensor please? Would save the other half having to use a torch.

I will be using a normal strip led, but I will drive it using PWM to dim it. Then I can use software to control the light level. I will put a light level sensor in the circuit to see what the light level is like. If the light is over a certain level it won't switch on at all (daylight). As evening falls the light will get brighter. However once it gets fully dark it will dim down again as not as much light is required. It should be fully automatic.

Each strip of LED's will be operated by a separate sensor so you could in a long van have multiple sensors and multiple led strips. For my van a single 1 mtr strip will be fine and a single sensor. The LED's in mine will come on an stay on for say 3 minutes then gradually start to dim, mine will also be linked to a separate LED strip in the toilet area itself so I don't have to turn the main light on in there either. I will point out that my van is a self build and I have wired it myself and have access to all the wiring

I will publish all the code and circuits I use so it can be replicated by anyone.

I haven't really thought this one through fully yet. Just some random thoughts based on your question.

^{_{Subscribers  do not see these advertisements}}

 

[OldAgeTravellers]

Praps you should have another sensor to lift the lid so you can do it all in your sleep or maybe that is just one step to far.
Joking aside a great set of projects, I can handle the construction & soldering, but the design and programming is beyond me. Unfortunately I went the mechanical and production engineering route rather than electronics and have regretted it ever since. It is great that you are prepared to share all this with us all though. Thanks very much.
Steve

 

[Gromett]

Praps you should have another sensor to lift the lid so you can do it all in your sleep or maybe that is just one step to far.
Joking aside a great set of projects, I can handle the construction & soldering, but the design and programming is beyond me. Unfortunately I went the mechanical and production engineering route rather than electronics and have regretted it ever since. It is great that you are prepared to share all this with us all though. Thanks very much.
Steve

I am single so the lid gets left up all the time. If I am sleepy and the lid happens to be down I will sit down. I ain't fussy

I share because I am a big fan of opensource, my businesses over the last 20 years wouldn't have been possible without others sharing their code. For instance I am typing this on an open source browser, running on an open source operating system. Linus Torvald's sharing philosophy has rubbed off on me.

Hopefully there will be people who use it who can improve it and will offer those improvements back to the project(s).

 

[Gromett]

I am getting bored waiting for the parts to arrive from China so have ordered a small qty of each via ebay with fast delivery. Should be here Wednesday for me to collect Thursday.

^{_{Subscribers  do not see these advertisements}}

 

[Baycott]

I am getting bored waiting for the parts to arrive from China so have ordered a small qty of each via ebay with fast delivery. Should be here Wednesday for me to collect Thursday.

You know the Chinese parts will arrive the day before the EBay ones don't you?

 

[Gromett]

You know the Chinese parts will arrive the day before the EBay ones don't you?

Yup. That would be great When I used to wait for a bus or taxi they were always late. They would always show up the second I lit a cigarette though.. Hoping the same happens here. If not I will still be able to crack on

 

[jockaneezer]

Unfortunately I went the mechanical and production engineering route rather than electronics and have regretted it ever since.

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

^{_{Subscribers  do not see these advertisements}}