Building a wine storage cabinet

Forums › Gadgets, robotics, home automation, electronics (including wearables) › Building a wine storage cabinet

lebleaux

12 posts

Geek

#284677 9-May-2021 19:11

I am intending to build a wine storage cabinet - intention is to hold the cabinet at a constant temp range of 11-13 degrees using a peltier device. Cabinet will be made of panels that are 4mm ply on each side of 25mm polystyrene sheet and will be built around a 48 bottle metal wine rack that has been gathering dust in my garage for some time. I have built a prototype using a polystyrene chilly bin and it looks like the temp is achievable with a single peltier but I will probably use two. Now for my problem. I would like to mount some kind of sensor at each position on the rack to determine whether there is a bottle there. Looks like the cheapest way to do this is with a mechanical micro switch mounted in some way (I can 3d print a suitable mount), but I can not find a simple method of managing the disposition of 48 micro switches with Arduino or Raspberry Pi - can work with either. Also, limit switches are deemed to be 'momentary' - ie you press them and then let them go. I don't know what will happen if they are held down constantly. Can anyone point me in the right direction.

Thanks in anticipation.

1 | 2

3512 posts

Uber Geek

Trusted

#2704128 9-May-2021 19:40

You can use a multiplexer (mux) to add additional sensors to an arduino.

What are the sensors for? Are you monitoring each individual slot or is the the total number of bottles?

nickb800

2715 posts

Uber Geek

Trusted

#2704132 9-May-2021 19:47

I think you need a 'multiplexer' between the limit switches and your raspberry pi/Arduino. The limit switches should be fine being held in the on position - just note that they can take a bit of trial and error with mounting

nickb800

2715 posts

Uber Geek

Trusted

#2704133 9-May-2021 19:47

mattenz

190 posts

Master Geek

#2704134 9-May-2021 20:02

You might want to look at polyisocyanurate for insulation, which is slightly better than polystyrene (but then you might have that lying around!).

lebleaux

12 posts

Geek

#2704140 9-May-2021 20:27

Sensors are to monitor each slot, get this working then I can keep a list of what is in there. Any chance you can think of a model, brand or id of a suitable Mux - I will go look. Yep, I have polystyrene sheets already.

mdf

3512 posts

Uber Geek

Trusted

#2704146 9-May-2021 20:48

Sparkfun has a whole category but there are always eBay AliX generic equivalents: https://www.sparkfun.com/categories/350

I'm not sure how reliable limit switches will be with wine bottles, given there are different shapes. Would you mount them at the back or underneath? I'm wondering if something like a photoresistor could work? That would rely on a clear door or other light source though I guess.

Ge0rge

2052 posts

Uber Geek

Trusted

Lifetime subscriber

#2704150 9-May-2021 21:12

Have you thought about using capacitive sensors? One installed at the back of each bottle position would easily sense the presence of a bottle and mean no moving parts to worry about.

Equinox IT

Cloud spending continues to surge globally, but most organisations haven’t made the changes necessary to maximise the value and cost-efficiency benefits of their cloud investments. Download the whitepaper From Overspend to Advantage now.

djtOtago

1149 posts

Uber Geek

#2704151 9-May-2021 21:31

I doubt a capacitive sensor would detect glass. They usually only detect things that are conductive.

Ge0rge

2052 posts

Uber Geek

Trusted

Lifetime subscriber

#2704196 9-May-2021 21:41

djtOtago:

I doubt a capacitive sensor would detect glass. They usually only detect things that are conductive.

The sensors that I've used to detect dry feed levels in a pig farm must have missed that memo...

neb

11294 posts

Uber Geek

Trusted

Lifetime subscriber

#2704208 9-May-2021 23:10

Slightly different approach, point a cheap bullet camera at it and use one of the embedded TPU devices/add-ons to detect where there are bottles.

lebleaux

12 posts

Geek

#2706659 12-May-2021 19:08

Thanks everyone. I am going to investigate the use of a Raspberry Pico (or maybe two) with a multiplexer and physical switches and/or buttons. Happy to share progress if anyone is interested, but it will be a few weeks before anything happens as I seem to find myself in a busy period with my day job.

lebleaux

12 posts

Geek

#2748653 23-Jul-2021 10:15

OK, we are up and running. Cabinet has been completed and Peltiers installed. However, I have a problem. The peltiers appear to be too efficient and are freezing on the cold side. As soon as a layer of ice builds up then this acts as an insulation layer and heat transfer effectively stops. I need to find a way to stop this from happening. Does anyone have any experience with peltier units. I am wondering if a bigger heatsink on the cold side will decrease the temperature differential - I am after cooling, not freezing after all. Todays mission is to hang a couple of temperature probes off a raspberry pi and find out what is going on inside the box

mattenz

190 posts

Master Geek

#2748656 23-Jul-2021 10:24

Have you got fans? Cheap heatsinks might also help.

lebleaux

12 posts

Geek

#2748657 23-Jul-2021 10:32

The units have big heatsink and fan on the hot side and small heatsink and fan on the cold side. Cold side heatsin k and fan turn into an iceblock in a relatively short space of time. Theory says that the more heat you remove from the hot side then the colder the other side gets. Perhaps I should simply disable to hot side fan and see what happens - need to get some accurate temperature measurement inside and outside the box - todays problem

mattenz

190 posts

Master Geek

#2748665 23-Jul-2021 10:48

Are you using a PID controller for temperature? Does it continue to freeze even after getting to temperature? I suppose if you don't have a drain, it's going to be a problem regardless.

I've recently been playing with ESPHome, and it is really excellent for controlling things like this (it also has a PID component). You could use the RPi for a Home Assistant hub if you haven't already got one.

1 | 2