I needed to turn on a 120 volt dust collector whenever the 240 volt for my table saw was turned on. This relay box takes the 240 volt from the table saw to activate a relay to turn on a separate circuit. woodgears.ca/mo...
It's cool how using the phone charger has the side effect of leaving the dust collector on for a few seconds after the saw turns off. Since the relay provides very little load to the charger, the capacitors stay charged for a little while and will make sure to suck up as much dust as possible.
The phone charger probably has a smoothing capacitor in it, and the solid state relay control side likely has a very low current draw/very high resistance, like a FET gate. So it probably takes a few seconds to bleed off that capacitor’s charge down to the minimum turn-on voltage for the relay.
AAAHHH so many exposed contacts squeezed in that box.. how about some electrical tape or shrink tubing to cover that up? Sorry, years of electrical engineering being forced to pass CE/UL testing. Also would love to know how hot that aluminum plate gets (and more importantly the relay itself). Not sure a solid plate with no radiating fins is sufficient for that if you happen to run your table saw for long periods of time (like your baseboard video).
AF he did earth the metal box, look carefully at 4:43, he tied both incoming grounds directly to the box and continued through to the ground of the socket.
At first I was thinking it's kind of a bummer that the relay doesn't switch off immediately, but then watching the final product it actually is kind of nice to keep the dust collector running a few seconds after the saw. One last tidy up after the dust maker stops.
ya, would have been smarter to let the huge piece which weights 20 times more to fall down......even more to put his barefoot under, to amputate one or two fingers.
Relay box ..sometimes has 5 way to switch electricity ..for example when the electricity goes from A to b when the C is switch on but the electricity can change the path from D to E when the C is switch off..that's the job of the Relay box
I often don't understand what happens in his videos. I have none of his mashines I'm not thinking about getting one of those like ever. I'll probably never going to do anything even close to what he does in my life. But I still watch every video and enjoy it. Am I weird?
sometime we saw ..fighting films like bruce lee but we can't do any karaté technique..but we still enjoy the show ..it's looks like that ! not a weird ..human nature is curiosity !
Hamza Kamel thank you for stating the obvious. The European weenies’ argument is that their system is superior because their entire continent had to be rebuilt from scratch after they all attempted to murder each other in the 40’s. Or something like that.
If you wire an electrolytic capacitor across the low voltage side of the relay, you can get a time delay before it turns off, which will remove any dust still in the system. Make sure the voltage of the capacitor is higher than the LV supply, maybe start with a value around 500uF A simpler solution would have been a normal relay with a 240v coil
i will buy relay box with inverter and batteries to make my own electricity when the public electricity will gone ..any idea or video ! (i need some advices)
I love watching your videos. I like how you always think outside of the box but it also gives me a look into the future to see what John Heisz will be posting soon after or complaining about.
I love how when you make it safer than what you had, and probably about as safe as anything you would buy you get all the safety police out about all the exposed contacts INSIDE your box. LOL In my case I have mine wired like you had yours originally- I mounted a separate electrical box on the side of my saw, and used an outlet that can be split into 2 separate circuits like yours, and wired one side to one leg and the ground before the table saw switch and the other side to one leg and the ground after the table saw switch, giving me a switched 120VAC for he collector and an always hot 120VAC that gets used for thing like sanders and if I want to use the collector to clean up when the saw is not on. Yea, I could get zapped with 120VAC if the ground feed broke, but that's seriously unlikely and even still, how many of us that have ever tinkered with anything like this before hasn't zapped themselves a few times before. I would reconsider if it was something my kids would use or if it was an item for sale, but if my kids are using my tablesaw, well the saw is more dangerous than the circuit and I'm not selling my 40y/o table saw.
If the ground broke, chances are you would not notice that the table saw is hot. When I was about 16, fixing one of those old tube TVs where chassis is connected to one side of the lead with an unpolarized plug. Every time I plugged it in, I'd swipe my hand across it to make sure it wasn't hot. After about ten times, I figured, what are the odds that I plugged it in so chassis is neutral every time? So I checked it with a phase tester. Half the time, it had been hot. But without me touching ground anywhere, I just never noticed.
Yea, I've been in that situation also. Honestly, my point was more along the lines of, "I'm surprised you bothered, I mean I get it but surprised, I'm doing the same thing that you were and not too worried about it." ;-)
The best solution would just to use industrial stacking switches, they do exactly what Matthias is doing here all the time in industry. He has a very common problem, power on or signal a low voltage circuit with a high voltage circuit. Matthias has an interesting solution, and i'm sure he's smart enough to be safe enough to be just fine. After all, people used to keep themselves alive with just the muscle between their ears, they didn't have everyone around them constantly making OSHA approved cowboys (google it, its funny). But if I were doing this, i'd just buy $40 worth of stacking switches. One stage of the stack can switch the 240V section, then you can stage a 120V section off the same switch. Then the 240V and 120V sections are completely isolated, any broken wires then follow the same flow paths as individual 240V and 120V circuits. Props for ingenuity though.
Be sure you understand the failure modes of an SSR : half wave (partial on) or on (full on). Half-wave can supply a less than desired output to your dust collector. No problem if the dust collector motor will handle a half-wave source. Big problems if it won't. Nice thing about mechanical relays is they generally fail off.
If it goes half wave, that would be a problem. It would quickly blow the thermal on the motor (and I know the motor has a thermal, because at some point I accidentally jammed the starter switch shut, and it cut power after about a minute)
Yeah, why not use a mechanical relay? They pretty much can't fail on when running AC. And you can basically forget what has been said about half waves. This project doesn't benefit from click-less switching or fast switching anyways.
I'd have used a mechanical relay both for simplicity and reliability as I'm normally building for others. This works and importantly, it'll be never used unsupervised and any failures won't be dangerous, just dusty. So it's valid.
If you are wondering why Matthias used a SSR, then you haven't been watching enough of his videos. The simple reason is, because he had them laying around.
John Heisz did the same thing, but he put a diode bridge in series with the saw, and used the output of that to power the relay. But that was a 1 phase chopsaw. On one hand the american system looks cool in the way that you can choose between 120 and 240 volts. But Europe and post-USSR countries have 3 phases, and when taking any 2 you get 380 or 400 volts, that is in turn useful for high power devices. In the end I'd rather have the higher voltages, because I'd rather pay for some insulation (for the volts) than for additional copper(for the amps).
You are a very productive man Matthias, I probably would have just put a second switch next to the table saw power switch but you took it to the next level and I think that is really cool.
Yup, a european 'electrician' here. Power distribution systems differ wildly around the planet. This excellent channel has viewers around the planet. What may be safe in one country can be very dangerous in another. It's NOT just frequency and voltage that differs. Phasing and earthing (protective conductor) have critical differences. If you know what you are doing, and it's legal, fine. If not, get someoene in who does. This stuff can kill. I'm not commenting on US practice because I am not competent to do so. Don't go commenting on practice elsewhere if you don't understand it either. BobUK.
Matthias, can we get a tear down video of that electrical box and snarky review of all these comments for this video. I mean, I love watching your stuff and when you build it. But half the fun is also look for the COMMENT WARS. I love both sides actually. One can not exist without the other. Would love a snappy reply while you review your own electrial box in a tear down. Great work! Keep up being intresting!
That relay box made me feel fuzzy with all of those exposed connections. I had the same feeling when you were wiring the 240v breaker, it looked like your hand was very close to the terminals. I bet getting a shock from that isn't fun.
Not to defend the design, but if the terminals are only air-insulated, I wouldn't trust crappy zip ties to hold the psu in place. Too many of the ones from the store get brittle in a few years. At least the wire won't plausibly embrittle and let the psu loose.
Now you need to build a delay circuit to keep the fan running for 30-60 seconds after the saw is shut off. Sometimes you are saying "ground", but what you want is "neutral", other times you do mean ground. Ground is not neutral, but nuetral is grounded. I wired mine so the table saw switch controls the vacuum. Much more ghetto, barely within the specifications of the switch that's 20 years old, but it works.
I definitely need a "real life FFW button" like 03:18 :D I'm interested in how long your SSR does the job. Got a bunch of them and two relays fail after less than 6 months... Great Job Matthias, thanks for sharing!
For all who are worried about Matthias' building techniques, perhaps there are some points I can make which may give some of you peace of mind. First of all, I am an "electrical engineer", degree and all. That isn't too important for this comment, but it may be important for some people who would worry all day and into the night about the credibility of my comments! Next, I have designed and often built projects such as this. When doing them for myself, some began about like this, and often didn't get beyond this kind of "prototype" construction. Some connections did not have insulation, some did, depending on the likelihood that they could touch other power carrying connections, which it appears is the same for this one. Generally, the more rigid the wires were, the less concern I had for their ⚓️ anchoring to something likely to be safer than safe. Finally, there are some whose house wiring is worse than this! For example, it is common to use a "flying lead" or "flying wire" to install an outlet where the box which will contain a duplex AC connector is difficult to reach for the electrician doing the wiring. In a few cases, it would be impossible to fit a small screwdriver into the box 📦 which the AC outlet will be installed. Physically impossible! So, the ⚡️ electrician who is charged with installing the outlet will add a short "flying wire " ( a wire that is very short, perhaps only four inches long, with enough insulation removed from each end of the wire to make a solid connection but with enough still remaining in the middle of the wire to insulate the wire from surrounding connections) to the outlet's connection screws, which then may be connected to the incoming wires with a simple "wire nut" connection. If this procedure is demonstrated on a typical connection to an electrical outlet that is hard to reach, it quickly becomes obvious that the flying wire is the only way the outlet may be wired. To the casual observer, it would appear virtually identical to some of the "floating" connections in a box 📦 like the one ☝️ shown in this video! The conclusion? The connection is safe, as are these.
Andrew Frink I've started seeing wago connectors at some specialty stores in Canada. But at about 5 times the cost, (50 cents vs 10 cents) it usually doesn't make sense. But a 5 wire wago is fantastic, especially compared to the shit show involved in joining 4 or 5 neutrals in a home wiring situation with a giant wirenut. They are about a dollar, but it's a no brainer for me given how rarely it comes up.
Andrew Frink I agree, we don't use wiring nuts in the UK, but the Wago connectors are considerably more expensive than connector blocks. I love how compact the Wago connectors are though.
This is exactly the same system I have on my laser for fume extraction. The laser outputs a 48v DC trigger to say the shutter is open and ready to fire, and I use that to switch a cheap Chinese SSR, and that automatically switches 240v to the fume extractor. Works fine.
White lithium grease works as heatsink compound and you can pick it up in 1lb tubs in the automotive section of Walmart. It's used to grease axle bearings on boat trailers. Look for LubriMatic White Grease 1lb 8 bucks
One small point- fine saw dust does not burn with a flame ,it smolders so if that relay gets too hot and too much saw dust you've got a problem just a word to the wise.
Hi Matthias. I've built a number of accessory switches, but using old fashioned relays. Very minimal voltage drop across the contacts. I prefer octal based industrial relays mounted on a din rail - very easy to wire up. Very useful as well for safety interlocks. But, I expect you had rescued the solid state one from some pre-owned gadget. Much cheaper! I like coil relays. You can see things moving ..... BobUK.
You should look into contactors. They have internal rectifiers that rectify the voltage on the "coil" side and can run 120-230v on the coil side they eliminate the need to have a low voltage source.
You might be able to use one of the 220 legs as the core of a transformer, winding it with many turns of a thin gauge solid core wire, and use that to trigger the SSR. Just an idea, may make the project simpler for some / require fewer parts.
Your table saw uses split-phase and not two-phase power. Residential power is split-phase. This is why 240V induction motors require a capacitor to create the second phase.
rotate85 I know, people always two phase and it always hits my ears sideways. They also argue if it's a wye or delta and have equality bad explanations for their opinions. I just say, "no it's not, it's a three wire Edison system" and then don't explain myself.
Neither term really expresses why the motor needs what it needs to start; certainly a capacitor is not the only solution to creating torque with a single phase input.
Richard, people have argued that single phase motors are star(wye) or delta wound?! Thats a new one to me, I guess i'm not surprised though. I don't think it was edison who came up with multiphase systems though.
Good project with a surprisingly efficient homebuilt blower. I'm sure you already know, but I'm gonna say it anyways. 1, no bushing on where your 120v comes into the box. 2, copper wire is an awful choice for mounting things inside of an electrical enclosure. Like I said, I'm sure you know and are aware of the risks, but are your viewers? Will some regular Joe following along know to immediately disconnect power and inspect when he sees signs of chafing and cutting on the 120v input?
Having tried using regular grease as thermal grease before, I cant recommend it. From my experience, it may as well have not been there, and it gets kinda gross.
You can buy aluminium electrical boxes. Gotta go to a real electrical supply house though. If I remember correctly automotive spade terminals fit over electrical plug prongs too. That bit of a delay when the relay turns off is a nice feature.
If you were going through the trouble of running an extension cord over there anyway you could have just wired one of the 240 phases to the neutral of the extension cord. The hot line would be controlled by your saw switch, go to the blower and return through the neutral of the extension cord. No relay required. You can still wire the top half of the plug to the extension cord to be always on.
your comment 'it works'; I never doubted it. only wish I could follow what you did. Too many wires going every which way. but I love it all the same, thanks.
The 120V circut is not isolated in the wirering box... maybe the whole box will have current on it if the parts move inside the box due to vibrations. This is hart to watch as a german electrician. :)
Oh, good to know. Didn't run across any on my search initially, but if I search AC-AC solid state relay, I see them. I should buy one for future projects.
The dedicated neutral is the safest approach. Current returns to the source via the lowest resistance path. If something goes wrong in the wiring and shorts to the hot, the equipment grounding conductor (neutral) provides a low resistance path so current returns on the wire rather than through you. The metal chassis should be tied to the equipment grounding conductor that goes back to your electrical panel. Note:, grounding to the earth is not sufficient it needs to go back to the panel.
Neutral is absolutely positively NOT to be used as an equipment grounding conductor. Neutral is a current carrying conductor. No current carrying conductor should be used as an equipment ground.
my projects looks pretty much the same in term of electrical wires, maybe with shrink tube... but I can't wait for the "are you crazy?? it's so dangerous this way!!" posts
I really can't follow what he's doing here, but holy smokes I love watching these videos. It makes me feel happy that there are these super smart men out there who will keep getting us out of the trouble we seem to keep getting ourselves into. Big shout out to all you men in your work shops with tools ❤❤❤
It's always such a break from RU-vid's mess of foaming from the mouth autoplay's and recommended to just watching something knowledgeable that can actually be done in the modern household. The only gripe is how you didn't tape/cover up any exposed contacts. Also a question, what's the best plastic to use for projects like these? And is there any garage type worktable we could get for it?
I was planning to build a similar solution but with a HALL effect sensor. It detects current flow in the power cord, so no modification needed on the tool.
Alec J I guess Matthias also just learned it the hard way. Though 110 volts doesnt hurt much. I have had 230 volts on me for many times (return path via shoes to ground though, via neutral will be much worse, but that isnt the case at this table saw scenario either).
not an electrical engineer here, but even i could see there was a lot of risk of doing that, also i'd recommend using thermal paste instead of grease and a small tube isn't that expansive so please do a follow up video about this where you do things a bit more properly here
Use a current-sensing-relay. Then you don't need any electrical connection between the 120v dust-collector and the 240v table saw. Just pass the 240v wire through the sensing circuit.
Only problem with this is that the Nokia charger cable should be replaced. I don't know what is it about the cable but after a few years (and considering, there's no argument that it is old) starts leaking copper oxidation through it and eventually, the jacket just fails. I replaced all of my cords because otherwise, those chargers know no death. I still use my original N97 one with an USB adapter to charge my 1020.
why did you use a solid state relay? couldn't you just use a Contactor with a 240V coil, because that doesn't get hot if I remeber correctly, contactors are made for switching big loads like motors, its like a normal relay but a bit rated for a higher current. Also it has 2 break points so that it can't arc that much across the contacts.
For those of you who are wondering whether this gizmo is something a real engineer would build, I have two slightly-related stories. Once, a young colleague asked me to help him attach a circuit board to an optical mount - used to position it precisely. I looked at it and said, all you have to do is drill and tap two holes in the front plate, and you're done. And he said: "Would you mind doing that for me? I have never drilled a hole before." This is a guy with a PhD in experimental astrophysics. Story number two: a friend who is a chemistry professor told his graduate student to grab a screwdriver and help with something. Eyes widen in fear: he had never used a screwdriver before. These are the people who are designing airplanes and software. Run and hide now!
That is exactly what he said at the beginning of the video. You are not supposed to use ground as a neutral. And in this video he shows how to avoid doing that. Did you watch the video?
do you have any videos that you go through and take apart old stuff deciding what to keep, why, etc? Because you had tons of little things that you've obviously pulled out of "the trash" (or free on the side of the road) to use in projects. It'd be cool to know what you look for and how
All those electrics inside. I'll just mount this using copper wire. ............... Woah.... I'm no electrician not even a bit but that just seems wrong. I worry for Mathias sometimes.
Using metal is actually good. If there ever is a short, it could come in contact with the copper wire, which is attached to the metal box, which is grounded. In other words, there is a path for the power to go other than waiting for a human to touch it which would create a path hurting someone.
You don't use whole-house GFCIs? In Europe they're required since the 90s, for fire safety. Wiring a load's neutral to ground is also prohibited, even though it technically works without a GFCI, for the exact reasons you described...
EU systems are more dangerous, you need whole house GFCI to reach our level of safety without them. We also use metal boxes to eliminate most electrical fires from arcing, they are grounded so if power goes to the casing, just like any other appliance, the breaker trips. Don't worry, our safety nazi's are trying to push these expensive devices on us. Admittedly they are cheaper in the EU due to economy of scale but here they are in the hundreds of dollars. all sleeping spaces now need arc fault protection which is different than GFCI, to prevent fires that are already prevented by the metal boxes... mostly they become nuisance devices now that don't add any real safety but they sure cost a lot.
You have a handy idea, However you created an extension cord with two male ends, This is dangerous because the blades of the male end you plugged into the outlet would be hot and exposed when not plugged in. I couldn't look when you used bare copper wire to anchor components. I get nervous any time you get an electrical idea
Clever but how is that safer? Isn't the transformer in the cell phone wall wart connected between ground and one of the hots? Seems to me that the same danger of losing the ground exists, how much resistance is in the primary winding of that wall wart? Just curious, I love your videos, they are quick, to the point and phun ! Thanks for sharing
no the cellphone wart is connected across the hots. Those cheap ones are mass produced for all over the world and it's cheaper to create a single switch mode powersupply module that can take both 110 and 240V and just swap out the plug part as needed.
great video. thanks for sharing. i would sketch up a single line and throw it in the project box incase you forget how its wired up or if someone in the future uses it. Also did you you ground the project box?
It is so much easier in a country with 240V 10A as the standard in household GPO, just have an ordinary switch to control the power going to a double outlet to turn the machine and dust extraction on and off at the same time. Surely that "earth" in your 240V line has to be a neutral (with two active phases)? Otherwise the earth leakage protection should trip in your fusebox every time power was applied.
i actually wonder they have these floormats made for putting cables under,are they actually usefull,or are they in general just usefull if you move things around on wheels a lot/thicker cables?i think they are most of the time made out of a steel or plastic and they kinda are like a roadbump
could be useful if other people walked around, but really hard to roll stuff over. I think I'd rather lift the cable when I need to roll something. The cable runs where I don't walk much.
