Variacs

[Joint hogger]

she's had smoke ?

 

thats because she didn't use a relay with the variac's, she'd be best advised to switch it off & unplug it then check inside for any damage or what's causing the smoke.

 

as for using two variac's, in all honesty, I prefer to use just the one, having a three step voltage supply is a bit of a pain to set up & is just complicating thing's,

imo, all you need is two setting's, 1. your temp setting & 2. the 100% override power setting (max temp setting).

 

for an example of a cracking single variac & a thermostate build is Laphroaig's easy single variac build.

[SamBell]

I think SexiSarh is a bloke. His profile said male and I think I saw some posts where he referred to himself. I don't think they've been on the site for a while though, so I jump-started this thread.

The smoke looked like a problem during construction (page 7 or so of this thread), but it read like he finally got there. My query was really about skipping the relay, but by the sounds of it that is not possible. That makes sense too, considering other designs do have the relay.

I've got an 8" extract and it's a bit much for anything but the height of flower (or veg on really hot days). Two adjustable speeds, one either side of the thermostat's setting, would be good. The Klimavator had user-set speed at a temperature, or 100%. An upgrade, in both no-buzzing and functionality would be nice :)

Though the Klimavator's 100% seemed slower than not having it there at all. When the klimavator died and I just put a mains plug on the extract, the air flow seemed to be much higher. I wonder if that is just a consequence of the thyristor design (I think) they use?

Laph's build is a good 'un, https://www.uk420.com/boards/index.php?/topic/301771-laphs-easy-single-variac-fan-control/&page=1 , but just getting a plain CH thermostat from ScrewToolFixation&Q for a few quid would be preferential.

Edited September 15, 2017 by SamBell

[Joint hogger]

whats the specs of your extraction fan ?

[SamBell]

Exactly? Not sure :) It's an 8" RVK, but not sure if an A or L, if those are the two classes.

I replaced a 6" with this 8", and it is significantly more powerful. It was a straight swap with another grower, for whom the 8" would have been obscene overkill. I can't really get to the fan now though, it's right at the back behind the plants, boxed off with mylar on cardboard, and suspended and not really movable - the label might be on the far side too.

I have played it safe and got 2A variacs, they were only a few quid more than the 1A.

Edited September 16, 2017 by SamBell

[SamBell]

I've now got together all the bits, and put together the basics.

Salus RT100 cheapo CH thermostat
2x 2A variac
SPDT relay and DIN mount
DIN rail
big junction box
300V voltmeter
1A and 2A fuses, surface mount holders
compression glands for cables
self-adhesive clips to hold down wires

Naturally I got assembly a bit wrong, one variac's rotor just touched the inside of the huge junction box after being fitted to the lid, so had to sand the wall to make it a bit thinner. I put the thermostat on the surface of the box only to later think about the heat from the box confusing things, and lack of flexibility in temperature measurement. And I marked out the front of the box only to turn it over and work on the inside upside-down. With drilling and no checking, of course! I was blinded by how chuffed I was with the paper template I'd made to get the holes "right" for the variacs.

Measure once, smoke twice? That's the rule for this kind of work, 'cause that's what I did.....

I've done a circuit diagram and would love it if the knowledgeable could check it over. I have set it out so that if the thermostat or relay fail, but still conduct electricity, the extract fan will default to the high-temp variac. I am not sure about fuses, perhaps fuses 3 and 4 are not needed? Maybe the variac outputs need fusing? Are 1A fuses enough?

The left variac is cool temp, the right one is high temp. I forgot to label them.



I know it looks like the thermostat is wired up wrong, with my cooling system connected to the thermostat's heating pole. I would prefer it that the relay's coil is not energised for the fan to be on high speed: the thermostat turns the fans down, rather than up.

Even so, I was even more baked when I did the diagram on paper last night, so this lot could be miles off. There is no way I could have gotten this far without everyone else's posts on this, Joint hogger and Clay Davis, Laphroaig of course. Other threads like Solo Seeker's. Plus all the people who've chipped in in discussions with little gems that just help.

Putting this diagram into the computer I realised it looks like the left variac's neutral is not wired properly. But the other way of doing it would be like a ring, and I don't think that is necessary.

Edited September 30, 2017 by SamBell

[SamBell]

Here's some pictures of what is together so far.

The variac scales are just taped on for the time being. All the fan speed components are top and right so that there is more space usable in the enclosure for future projects.




Inside, with the 2 2A variacs, the dodgy holes for the thermostat, the back of the voltmeter, and the relay.




The relay and a Raspberry Pi mounted on the DIN rail. Just test fitting for now, the Pi will be doing temperature logging, a camera or 3, light sensor and various alarms and alerts. Likely control at some point, too. I already do logging and alerts off a PC, but the Pi can be a bit more embedded.



I'm about ready to wire it up, but could do with an OK on the wiring diagram in my last post.

Cheers

Edited October 1, 2017 by SamBell

[Badders]

went through the diagrm and it looks okay to me, 

id swap the stat for a stc1000 - unless your gonna use the RPi to control temps? - 

Ive been using mine for a while to log but am reluctant to give it control hehe, - I could only get temps to work with ds18b20 - I really wanted to use a dht22 to get RH but struggled to get it working alongside the ds sensors, 

Best of luck dude, 

PS i wouldnt worry about all the fusing, put a single C or D type mcb at the incomer 

B 

 

Edited October 2, 2017 by Badders

[SamBell]

I did look into the more sophisticated controllers, but obviously not enough 'cause I've just seen they look to be pretty cheap. But I think a basic thermostat will be enough for the room. Effectively I want lights on/off based extract, but rather than timed temperature gives some flexibility. I can always change the thermostat later if it turns out to be crap.

I will be using 1 wire thermometers on the Pi's GPIO, at the moment have a single USB thermometer. Control might be handed over to Pi-net, but I'm worrying about it becoming self-aware :) But seriously, I'm not quite knowledgeable enough to trust building something that needs to work reliably for a couple of months. I've got plenty of hacking to do before giving software control.

Me and a mate talked about putting fuses on the rail, but only after the smoke cleared did I realise that to flip one the whole box would need opening. Surface mounted holders would be faster and more convenient.... not that I want to be having to reset any type of fuses.

Cheers for the advice, will get on to wiring it up tomorrow.

[Subliminal Criminal]

cool @SamBell

 

i have a pi3 that i bought to study electronics a bit.. was wondering if i could use it to remotely control a few things in my grow room

 

subs

[Badders]

you could, often the concern is long term reliability, - I know that my hardwire logic / relay is very unlikely to fail, I cannot be so sure with the RPi, although evidence suggests people having been running them for months with no problem im somewhat more suspect. 

 

[SamBell]

The Pi does have shortcomings:

The Pi has no hardware clock, so a power cut would mean controlled things won't necessarily come back on or stay off. Adding a HW clock is a basic project (not that I have even got that far with my Pis!). Most, if not all, Pi operating systems will set the clock at boot off the network. Though a power cut can mean an NTP server is not available.

SD cards aren't too reliable. A backup card and a known-good procedure to swap it out without major downtime is needed. The operating system can be modified to make things more resilient, and keeping essential data and configs on the LAN or a hard disk will help when the inevitable happens.


But there is a watchdog kernel module and daemon, so if a Pi's OS crashes the Broadcom SoC will auto-reboot. Essential for an embedded system.

So my Pi will be for monitoring and alerts to start with, and if control comes then it will be of non-essentials. Heh, the Pi in the photo was bought to be a media centre type thing for the lounge, controlling the stereo (at least) by IR connected to the GPIO. Probably best to learn how to control non-crucial stuff first :)

This is all very OT.

[SamBell]

The thing is now built, and apart from needing a mains lead making up to be the right length and the scales sticking on, it is working!

Well, not tried it with a fan yet. But meters make it look good.

I couldn't have done this if not for all the great threads and comments by so many people over the years. Davey Jones is big name I think I missed before, but if I haven't named people it is not out of discourtesy. Just stoned browsing, focusing on the messages, not the writer.


The front, with surface mounted fuses. All 1A at the moment, if I add fans later these can be upped to 2As. I went over-kill with fuses, through not knowing what I am doing, but also to keep people and components safe.



The back, with the power in and out. This might look Trumpian in its moronity, 'cause the box can't be wall mounted, but I have a void in the grow room where the box can be mounted. The CF stands on a table with a round hole cut in it for the pipe, and the controller box can go between the table legs. Controls facing outwards, wires going backwards and out the way



The insides. Yes, bits are probably naughty, like linking the two halves with just blue wires when it is a mix of LNE. And using the DIN rail to link the socket's earth to the mains supply earth. I could only get 3 tiny spade connectors for the fuse mounts, so soldered most of them. The output socket hole is a mess, the shape to be cut out wasn't nice and uniform. And the jigsaw blade was melting the plastic and so it tended to seal up again behind the blade. Everything's a bit crammed 'cause of the long-term plans for this to house a Raspberry Pi on the DIN rail.



And here's it powered up, with a multimeter poked into a clover-leaf mains lead, and showing pretty much the same as the square voltmeter. The pictures have the variacs set wrong, with the thermostat set low the voltage is high, but it is just a case of turning the knobs to correct that. 276V is it turned up to maximum - a level I will not run the extract fan at.

What is the most a fan can be turned up to? 250V? The mains here is 243V, according to my multimeter.




Here's the diagram of what I built, with all fuses.


Time for a celebratory joint
SB

[Davey Jones]

On 03/10/2017 at 8:20 AM, Badders said:

you could, often the concern is long term reliability, - I know that my hardwire logic / relay is very unlikely to fail, I cannot be so sure with the RPi, although evidence suggests people having been running them for months with no problem im somewhat more suspect. 

 

I dont know what you mean by hardwire logic/relay its a broad term but everything is certain to fail its just making the MTBF acceptable for the application

 

Its all about selecting the right tools for the right job and a Raspberry Pi is basically a PC, using a PC to switch on outputs or measure things is using a sledge hammer to crack a nut, a PC is a highly complex thing and not really suited to real time control in any way. System reliability is a whole subject in its own right, its really much more than making sure a transistor doesnt burn out once we introduce software then the job is much more complex 

 

If you require plug and play with minimal maintenance then your software has to be written to accommodate this, a simple watchdog timer goes a long way transient hardened software is also not so bad to implement then the complexity increases dramatically with things like CRC checksums to verify the integrity of flash memory being a difficult thing to actually implement. Doing these things on a PC is very challenging indeed

 

 

An Arduino is much better suited to grow room control working independently and feeding data to a master control which could be a raspberry Pi but I wouldnt, then again I am a diehard hardware guy and computer science has always bored the pants off me its too vague for my liking (I am a prickly person!)

 

 

On 03/10/2017 at 5:02 PM, SamBell said:

The Pi does have shortcomings:

The Pi has no hardware clock, so a power cut would mean controlled things won't necessarily come back on or stay off. Adding a HW clock is a basic project (not that I have even got that far with my Pis!). Most, if not all, Pi operating systems will set the clock at boot off the network. Though a power cut can mean an NTP server is not available.

SD cards aren't too reliable. A backup card and a known-good procedure to swap it out without major downtime is needed. The operating system can be modified to make things more resilient, and keeping essential data and configs on the LAN or a hard disk will help when the inevitable happens.


But there is a watchdog kernel module and daemon, so if a Pi's OS crashes the Broadcom SoC will auto-reboot. Essential for an embedded system.

So my Pi will be for monitoring and alerts to start with, and if control comes then it will be of non-essentials. Heh, the Pi in the photo was bought to be a media centre type thing for the lounge, controlling the stereo (at least) by IR connected to the GPIO. Probably best to learn how to control non-crucial stuff first

This is all very OT.

 

The Pi is lacking in a lot of departments when it comes to control and hardware, no ADC is a disgrace. I have tried to play around with them a lot and I am a fan but mostly because of things like Mathematica and Scilab, I dont think Matlab is available for the Pi which is a shame as Matlab is a fukin awesome tool its staggering what you can do with Matlab it makes you look really smart when your not even trying, recent versions of Matlab have Pi support and I have been threatening to do something fun with the two but never anytime

 

I did buy a beaglebone and a book for a Uni project which needed a high speed datalink, the SPI interface was really attractive but in the end it was just too much of a head fuk due to its hardware limitations and I wopund up using the existing DSP and I got 5MHz out of it without even trying it was a piece of piss in comparison to all that operating system shite. The Beaglebone is much more geared to control than the Pi and I had fun trying to use it

 

6 minutes ago, SamBell said:

Davey Jones is big name I think I missed before

 

Thanks man, you gave me a warm fuzzy feeling of being part of the human race and helping your fellow man by passing on info that was received by others, thats what its all about for me sharing the knowledge and helping others on the same road. There is no better feeling than teaching someone something and watching them blossom and in rare cases actually taking it further than you did, they end up teaching you something

 

I have posted a lot of stuff over the years and the amount I have learnt in the last two years alone impresses me, I have been on the boards ten years and sometimes I look back and my posts and think OMG I knew fuk all but its life innit

 

Thanks for your acknowledgement  but lets keep it real no matter who posted what that was only showing you where the water was you have drunk it and you nailed it dude, I havent reviewed your schematic or done any analysis at all except skim read but man ten out of ten for effort and ten out of ten for the result, well done dude you made me proud. Its amazing what a single human being can achieve with a little bit of enthusiasm and a load of determination

 

Nice one!

[Joint hogger]

nice effort Sam but imo, you've made it awkward by having the cable gland coming out the back of the enclosure instead of it coming out the bottom,

same as using the twin socket on the back too, you could have used a twin trailing socket coming out the bottom of the enclosure to keep thing's neat

or you could have used iec14 plug holder's like this.

 

 

can I ask why your running the variac at 240v or 270v  ?  

it also look's like you might have your live out & neutral's mixed up, the wiring for a 2A ravistat variac is - A: combined in & out neutral, C: live in, E: 240v live out, the other connection is D: 270v live out, which we dont use.

 

also, if your using the 270v dial & running at 240v, you need to reconsider the power running percentage, here's a pic to show you what I mean.

 

 

 

 

 

 

[SamBell]

Cheers Davey, and you're welcome. I posted the final wiring diagram (which needs changing), just the minor addition of fuses, in the hopes it is helpful for someone in the future. A complete record can be more inspiring. I'm no giant (who's shoulders can be stood on), but am just hoping to provide a little hand up. Ideas are useless if not shared, if not put into practice.... and with growing being a secret hobby it irks me I can't yell stuff from the roof tops.



The Pi running Linux cuts a lot of corners for me, I have used Linux primarily for many years now and so know how to reign things in and get things pretty much as stable as they can be.

How I do monitoring now is periodically, sampling things once a minute. I log temperatures, do some checks for the time of day, and alerts if wrong. And produce 2 graphs of temperatures, available off a web server on the LAN. I also use an IP camera (firewalled to fook - these things are plain dangerous) to measure the light levels, and alert if wrong (dark during plant day, light during plant night).

For the graphs the wrapper to gnuplot takes about a second and a half to plot ~74000 points, one second to do the last 24hour's graph. The PC is over ten years old, but even so the load average rarely breaks 0.1 (single core CPU - the Pi has 4 cores). How I have approached things I don't see any signs of needing RT, but I do appreciate that using other than polling could mean needing RT.

Some data logging here has been border-line metaphorical. Like using the camera to take a picture once a minute, then reviewing them by eye :) So I have used pictures to compare thermometers, to monitor humidity at night using the IR to light up an LCD hygrometer, and to monitor the supplementary CFL. They are on a plug-in thermostat which needs tweaking to cut the CFL off just right.



At the end of this I am kind amazed how in this digital era I have built a very analogue thing. I certainly didn't aim for the theme, but three knobs and a needle gauge? It has a retro feel. Electropunk, if that is a thing. The needle swings so satisfactorily when the relay switches, too.

How I approached this build was to draw my own wiring diagram. It only took three goes, and the last one still had scribbling-out, but when the thing went together as an abstract drawing I knew I was on the right path. The practical approach works better for other people, but in this case, 'cause mains electricity, trying the boring homework first is the best bet.

I was spaced out for about 2 hours trying to think how it should work though.... the CH thermostat is a cold switch, that is how to think about it. It turns on when things get cold, even though the machine we are building is meant to turn something up when it gets hot.

The costs might not be as inspiring. This cost a lot because I over-bought, in part because buying exact quantities is difficult (like the 2m of DIN rail I bought, when I needed a foot). Or because I didn't know how much I needed so went for bigger numbers - like 100 self-adhesive cable clips, or even the 2A variacs. I also bought several new tools, as I was missing a few things, or had crap versions. A decent wire stripper is essential, for example. Not sure of the total, and whilst I now have otherwise useful stuff I must have spent over 200UKP. Would have been more had I already not had some odds and sods about already.


------------------------


Joint Hogger, I know the stuff on the back looks dumb, but there is method to my madness. Connections would be in the way if I wall-mount this huge box, but I do have a gap under my carbon filter where the cables on the back will only be beneficial. Just grovelled into the room and took a photo, it's the plant's night time now. I'm going to fit the box between these table legs. The fan is behind the ducting, hanging in the grey trolley behind the table.




What you say about wiring it wrong is worrying though. I have wired it up according to Ravi's wiring diagram, which has D as 240V mains in and E as the variable output, 0-270V.

This is Ravi's diagram, hot-linked off their website and the same as the instructions bundled with the Ravistat:


I am certain I haven't got live and neutral mixed up, here's a better photo of the wiring. The wire colours here are correct, the crimp connector colours mean nothing.



Are you saying that these should be wired up so that when the knob is turned to maximum, it just passes on mains voltage? Personally that is what I would prefer, the knob can just be spun with no risk of damage to a fan.

....

OK, what it says on the black board about the wiring makes sense. Input of 240V across A+C, or A+D. The output is 240V or 270V across A+E, depending on the input wiring. The order they give the options explains the choices: A+C you get 0-240V, A+D you get 0-270V at E.

Is that right?

Yeah, here's scraglor saying the same:
http://www.uk420.com/boards/index.php?/topic/212361-correct-variac-wiring/&do=findComment&comment=2109459

if you put live from your mains to C, you will have 0-240v output on E, if you connect mains to D, you have 0-270v output on E, so wire it as wannabe jack says, but connect live from your mains to C, instead of D.

So I'll move the inputs to C.


Thanks for the percentage diagram, I had seen that in the past. The finishing touches are still to come, any recommendations on how to attach the scales? Superglue is often shit on plastic, hot glue stands to be a bit thick. There isn't really enough plastic to put in some screws..... Got some aerosol glue, I think. Gorilla glue, too, but I think that is superglue, and it expands (worked a treat to make the extract fan's case air-tight though).

Would it be bonkers to use a soldering iron? Press against the metal scale and the plastic behind will melt. Take the heat away and leave pressure, and the two might stick nicely.