Hello All,
Even tough I’ve read the forum rules and have tried to adhere to them i’ll like to appologice in advance for;
• Unknowingly breaking the rules
• The sheer volume of the project
• The “unique” way of presentation
• Grammar/spelling mistakes, english is not my first language
• Dumb things I say or ask, I have not been educated in these matters.
• My lenghty texts and info, I just try to be thourough for whoever is willing to help
• Size of the attatchment (27Mb), it contains pictures of every part, 3 schematics and photo's of the actual project. Attachment can be downloaded here I've also included just the new schematic for people who don't need all the info.
Brief introduction of the project
I’m building a brewing computer for my beer brewing hobby. It should be able to do a relatively simple task. Listen to a temp sensor, if target temp is lower than actual temp -> put on as many heaters as needed to reach the target temp. The recipe, variables and controls are accessible trough an app named Blynk (https://blynk.io) and the controls of the power also trough the hardware (toggle switches and buttons). In the future I would like to include a way to read the current load on one of the given groups by use of a hall sensor, I included it allready but did’nt hook it up to the wemos because I can’t calibrate it yet (apparantly I need to have some sort of wattmeter for this).
A more complete one and lessons learned thusfar (by all means, skip this if not interested I don’t think it’s needed for the questions part)
A couple of years ago I started brewing and made a simple brewing computer, from the get-go I ran into problems that took a lot (days, weeks, months) of time to solve.
• The power main (from the house) kept shutting down
- I think the biggest contributing factor was getting my power from extension cord to extension cord to extension cord, all with different specifications, I’ve since then bought 2,5mm2 power cords
- Computer or extension cords getting wet, I’ve since then built a better enclosure for both
• Arduino kept erroring or didnt start up
- turned out to be a mini led display hooked up, I’ve since then stopped using it
• Relays behaving eraticaly
- probably interference, in the new project I’ve included resistors on the digital lines in the schematic, hope to fix this issue this way
• Melting switches (a plastic part within the switch causing the switching mechanism to fail)
- Even tough the switches were rated to be able to carry this power a friend told me that’s only if you leave it on or off, not switching it on and of on a regular basis
- In the new schematic I’ve moved these 250VAC 15A to the DC part, hoping to solve this issue this way
So at this time i’m grudgingly getting ready to start on my BrewBucketBot 4.0 (i say that because I was sure I did everything right this time with version 3.0, for versions 1 - 3 see 05_legacy folder in attachment) and I just have to stop kidding myself; I will not finish this without help of people who actually know what they are doing. My grasp on the subject and principles of electronics are minimal at best and the simple fact is just that I don’t know what’s out there. I’ve talked to an electrician before making 3.0 and he gave me the go-ahead on all the components in the AC circuit. Well after one trial run 3 of the 9 buttons melted and the shiftregisters stopped working so I geuss i’m not done yet. Before writing this I talked to an electrical engineer, and he also gave me some pointers. Among which; seperate the AC and DC more, use PLC instead of arduino and the like (but that’s out of my price range).
So without furhter ado:
My questions
Main question;
- I’m hoping someone will want to look at my schematic and project and just point out the mistakes in it or give me tips on better hardware to fix some issues or prevent them in the future.
Sub questions
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My toggle switches say 250VAC 15A. it became apparent to me that they can’t actually handle this tough, by moving them from the AC part (of switching the power going to the relay on or of), to the DC part (of switching the power supply actualy powering the relay) I think I can achieve the same functionality, the button says 250VAC tough, can it also operate on 5VDC?
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It has been pointed out to me that some issues (relays behaving eraticaly, wemos wifi being flaky) could be cause by spikes in the power group caused by turning the high powered heaters on and off the entire time. Will the 470uF capacitor in my schematic fix this?
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Furthermore I’ve been told that applying a snubber diode accros a relay at the AC side could help protect the relays and the DC circuit (especially when switching on-off a solenoid valve), google as I might I cannot for the life of me find what diode I should need for this.
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It has been pointed out to me that some issues (relays behaving eraticaly) could be caused by “floating charges“. Will this be fixed by adding a 1K resistor to every digital pin going to a relay?
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I’ve read (See source 1) that using a audio jack for temp sensors might not be best practice but it can be done by inserting a 220 ohm resistor on the power pin, I’ve done this but still get weird readings related to connection issues (-127 or 85 as temp reading) when inserting, sometimes they go away imediatly, sometimes they stay a while. Can this be safeguarded in such a way that it is non-problematic?
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I’ve been told you’ve got to seperate AC and DC. How do you do this and how much distance/isolation is enough? for instance, a relay has AC on one side and DC on the other, how can you seperate this? if put in the DC part it mixes it’s AC there, if put in the AC part you’ve got your DC wires picking static up there.
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Before knowing this could be an issue I’ve allready built myself a sexy as hell computer enclosure (see attatchment folder; “05_oohlala“). Thing is, I’ve kind of dug my own grave with this I suspect, can I still isolate AC from DC here in this narrow space? is it as simple as I dunno.. shielding it of with a “cage of faraday“ principle wall thingy?
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If all of the pheripherals (all the heaters, pump, valve) are turned off but still in contact with my Stainless steel brewbucket the bucket gives a shock to the touch, not 220V but a really noticable shock nonetheless. If they are all on this is not the case. Somewhere I have some electrical leakage. If looking at my schematic, should I have this, am I missing some integral fale-safe to fix this?
Some facts
I’ve seen these questions asked to the op’s in other forums and posts because they were important for knowing some variables about power and local hardware settings etc. I tought i’d try to answer some of them beforehand
• I live in the Netherlands, Europe
• At my home I have 7 electrical groups
• When I brew I use the least used groups and even those used dont have all that much on them (television on standby for example)
• Our voltage is rated on 230V
• Our power groups are rated on 16 Amps per group
• We standard have Euro plugs with 1 neutral, 1 line, 1 ground.
• The usb entrance you see on the enclosure is just for programming the Wemos D1 Mini
• Pretty much all the AC wiring is 2,5mm2. Some small parts aren't but these are the wires that came with, for instance the led's
• All of the DC wiring has been done with salvaged wiring from a 50 meter ethernets cable
Attachments
For the generous soul out there who is willing to take a gander at this project I’ve tried to be as thorough as possible with all the information and attachments. In the attachments you’ll find;
01_Code (My projects code)
02_Blynk (Blynk interface screenshots)
03_Schematic (Shematic, both the failed one and the new one, also a legend to the hardware components)
04_Hardware (information and photo’s of hardware used, also a legend to the hardware components)
05_oohlala (damn that enclosure’s looks good)
06_Legacy (some of my earlier builds of this project, by all means, skip if not interested, I dont think it is relevant for this current project. It does show the long way I came from allready)
07_Problems (some evidence off the problems ran into)
Sources refferenced
1.)
Thanks in advance
NEW_Schematic.pdf (607 KB)
