I wondered if someone could help me to make sure I buy the right parts for this fume extractor I want to build? I am going to follow the design here on YouTube that this guy did:
I have 4 computer case cooling fans that are each:
12V DC
.16 A
120mm
1800 rpm
3 pin power (I know I don’t need the 3rd pin)
I was going to follow this guys video and wire all of the fan wire + to create a single + wire and all of the - fan wires to a single wire to create one single - wire. I want to wire it to a single on/off switch wire a wall-wart for power. The problem is that the links this guy gives in his video description either no longer work or go to incorrect parts.
If these are not correct can someone tell me which ones I should get?
Is the wiring this guy did okay or should there be anything else I should do differently? I think all he does is wire the single fan - wire to the - of the output jack and take a single wire that goes from the + of the output jack to the + of the switch? It doesn’t look like the switch has a ground on it in the video?
What type of wall-wart do I need to get? I thought it needed to be a 12VAC 6A?
The jack depends on what plug your power supply is using, but 2.1mm pin/5.5 mm plug diameter is a common size.
If you have four fans in parallel, each using 0.16 A, you need 4×0.16=0.64 A from the supply (plus a bit margin). A 12 V DC/1 A supply should be good enough, I think.
That power switch is fine for that load, just run the +12V through it and use it to turn the fans on and off (but note that the wart will still be powered if you turn off the fans, so you may want to unplug it if you’re not using the fan for a longer period).
Can someone help me with the wiring for this? I can’t tell from the datasheets which terminal is positive and which is negative on the rocker switch and the power jack. I would like to also add an LED to the chain so that I know when it is on and off. I have a 1k resistor and a 3mm LED, but not sure how to wire it to the switch. The datasheet / wiring diagram on Tayda for the rocker that I bought isn’t what I have in my hand, but the photo of it on their site is correct.
I have 4 fans that I am running in parallel. I believe I take the negative from the fans to the negative of the power jack. Then put a small lead from the positive of the power jack to the positive of the switch and then connect the positive from the fans to the positive on the switch. Is that right?
Where in this does the 1k resistor and LED go?
Which terminals are positive and which are negative on these components?
Any help would be greatly appreciated. This is my very first project…ever and since I’m dealing with a wall wart for power I don’t want to do this incorrectly.
Which part of the socket is positive and which is negative depends on the wall wart. It will have a symbol showing which is which. In the drawing below, I assume center positive, but you should check. The switch does not have polarity. Just wire one terminal on one side to one end of the positive wire and the corresponding terminal on the other side to a new wire that then is the switched positive. Then put the LED and resistor in series from that wire to the negative wire.
Knowing the wall wart is center positive, how do you know which pin is positive and which is negative of the 3? They are not labeled and the datasheet makes no sense to me.
On the rocker switch there are 4 terminals. I know you said that the switch doesn’t have polarity and that you basically have a wire on “each side.” However, in the photo below of the switch I am not sure if terminals 1 and 3 are considered to be on the same side since they are on the left side of the switch or if terminals 1 and 2 are on the same side because they literally are on the same side. If 1 and 3 are “on the same side” then I would wire the positive to 1 or 3 and then the negative to 2 or 4. Sorry if this is a stupid question. I just don’t want to screw this up.
Doing electronics without a continuity tester is asking for trouble. Get/borrow a cheap multimeter asap and use the continuity tester to figure out what’s connected to what.
(I’m quite fond of the Aneng AN800x series that you can get off e.g. Banggood for cheap, but any multimeter will do)
I actually have a multi-meter. I just didn’t realize it could give me the data I needed. I tested the terminals on both the socket and the switch and I know where continuity is flowing now on the switch and since there isn’t polarity on the switch that’s easy. The socket is a different story. I figured out that terminals 1 and 2 have continuity, but I cannot tell which one of these is positive because no matter which way I have the probes it still says “0”.
Pin 4 (see the PCB layout for what’s what) is connected to the center tip, i.e. +12 V in your case. Pin 3 is connected to the sleeve (0 V). Pin 2, the one on the side, is connected to pin 3 if nothing’s plugged in.
To verify, you can just plug it into the jack (before attaching it to anything), set the multimeter to voltage, and measure the voltage between pin 3 and 4 (red on pin 4, black on pin 3). The multimeter should show +12 V or so. If it shows a negative voltage, the above assumptions are wrong and you have to connect it the other way around.
As far as the rocker, it sounds like a DPST (Double Pole, Single Throw) switch.
Its a bit confusing at first, but you have 2 input terminals and 2 output terminals. The “pole” refers to the number of circuits you can control with this thing. Since you have 2 inputs and 2 outputs, you can control 2 “poles” with one “throw” of a switch.
I always forget which way switches have to be wired up too. I use a multi-meter in continuity mode to test the terminals and if it beeps when the circuit is closed, i know which two are the input and outputs. Ive got this exact rocker switch at home in my “prototype box”. I’ll look in there and take a pic to confirm.
You connect them “long ways”? I dont know how to best describe it. the pins look justified from the center in different amounts. you just want to use one of each to make a complete circuit.
Thanks Fredrik, that does make a lot of sense. I plugged in the jack to the socket and tried to check with the multimeter for a positive value, but no matter which way I have the probes it always says 0.00 with a neg line flashing. I double checked to make sure on a few YouTube videos and sites that I had the correct setting on my multimeter and I do so I don’t understand why I am not getting positive voltage. I tried a different socket to see if I just had a bad one, but all of them read the same values. So my only other thought was that I bought the wrong power supply? Would you be able to check the link and tell me if the one I got is incorrect? You said earlier 12V DC 1A. I went with a 2A as it was cheaper, but that shouldnt make a difference. It is switched so is that the issue? The guy on the video said switched (AC to DC) didn’t matter?
Output Connector: 2.1mm x 5.5mm center positive female barrel plug
so the next step is to figure out if it works. Set the multimeter to voltage, plug in the wall wart, stick the red (+) probe in the output plug’s center hole, and hold the black (−) probe against the sleeve (if the + probe doesn’t fit, you can use a bit of wire). You should see +12 V. If not, it’s either broken or (unlikely) some picky model that doesn’t turn on unless there’s a non-trivial load (the multimeter has a very high impedance).
Thanks Fredrik for double checking my supply and for the info. It looks like the supply is not working properly. I didn’t get any readings from it. I found a supply in storage that is the same voltage/amps and tried that one and that supply worked just fine. I am seeing +/- 12 volts on the socket now.
Perhaps another stupid question for you guys. Everything except the resistor all sit in the frame of the box that I am putting around my fans. So once I have soldered the resistor where it needs to go what do you recommend I do with it? Wrap it in electrical tape? Glue it to the inside of the box frame? Or something else? If there were more components I would put it on a board with everything else, but it’s the only component not in a housing so I wasn’t sure what to do with it.
Woops, sorry i just didnt initially understand this question!
You just want to know what to do with a component when its just dangly? Once you solder it up to what you need to, you may want to wrap it up with electrical tape, and make sure nothin will damage it. Perhaps a dab of hot glue to secure it to something safe after insulating with the electrical tape? Its a passive component, so there isnt much harm done really. These precautions are just to ensure you dont get a short and dont break it. If its just a resistor for an LED, the worst would be if the resistor died would probably just be a blown LED because of too much current draw.
This is just a pair of LEDs, the resistors were on the board. But something like this worked for me just fine.
The whole reason you need a resistor in the first place is that the current flowing across an LED (diodes in general) is an exponential function of voltage across the LED / diode. Even a small change in voltage can produce a huge change in current. For resistors however, the change in voltage is linear. So a change in voltage across a resistor will produce a proportional change in current.
Of course, if anyone else has a better solution, id love to hear.
@ChristianBloch@Caustic@fredrik can you guys help me again please? I am only just now getting around to getting these fans wired and I ran into a problem. I followed the diagram that Christian posted and triple checked my work, but it’s not working right. When I have the extractor plugged into the wall via the socket the fans turn on and the LED lights up. However, the switch does not turn off the fans at all. If I flip the switch nothing happens. I tried testing it by moving one of the wires connected to the switch to a different terminal but then the fans and LED didn’t turn on at all. I also checked to see if I was receiving any power to the switch thinking maybe that it was damaged but the multi meter was receiving data so it must be okay.
