Slowing down hair dryer fan motor - Page 1
Forum section: electronics / beginners

author: gorman2040
author_rank: Contributor
timestamp: October 10, 2024, 05:05:38 am
content: Hi there,I would like to slow down the fan motor of my hair dryer.It is a 100v 50/60Hz 1300w 5 speed, 5 heat level hair dryerThe heat levels are fine, however the fan speed is unacceptably loud and powerful even at the lowest settingI have already disassembled the body and have access to the main circuit board and provided some pictures of the insideI have basic soldering skills and am OK switching basic components like a resistorI would like to lower the fan speed for any settings, effectively giving me 5 speed settings that are lower than the original onesIf easier, I don't mind also lowering the heat produced by the hair dryerI am aware of the risk of fire if the fan speed is too lowI will mostly use the lower fan speed and heat, sort of a small heaterI don't need to keep the ION and hot/cold auto switch feature, if that helps modifying the hair dryerI am looking for guidance as I am not sure what each component does and if achieving this if feasible at my level and tools.Thank you in advance.

author: inse
author_rank: Super Contributor
timestamp: October 10, 2024, 05:19:44 am
content: Hello Gorman,that’s a lot of electronics for a hairdryer!Unfortunately by the single photo it’s impossible to give advice where to modify the circuit.As it apparently is micro controller controlled, a hardware hack might even be impossible.From the hairdryers I know, the fan speed and the heater power are somehow matched, so as you have already considered, increased temperature might come with reduced airflow to the point of over temperature shutdown.If you’re not so deeply into electronics, buying a quieter hairdryer might be the better way.

author: IanB
author_rank: Super Contributor
timestamp: October 10, 2024, 05:21:44 am
content: This is not something I would consider trying to do.However, if I were to consider it, the first step would be to look up all the components on the board to find out what they are. Then take photos of both sides of the circuit board, follow the traces, and draw a schematic diagram of the circuit. Using this information, attempt to reverse-engineer the design.If those steps were successful, then the next step would be to figure out how the design is used to control the heat level and motor speed, and see if there is a way to alter that by changing component values.All of that is very complicated, and someone would have to be very enthusiastic to attempt it.It could be easier and simpler to buy a different hair dryer.

author: gorman2040
author_rank: Contributor
timestamp: October 10, 2024, 06:29:29 am
content: Thank you for your input!I wanted to avoid buying a new hair dryer as it is very hard to find a 5 speed, 5 heat hair dryer (those are two separate settings BTW).The hair dryer is also new but from Japan so hard to sell here in Canada even though it works perfectly well.I used to have one that is no longer sold but the motor is now completely dying. This one was easy to slow down as it was for 220v and just using it on 110v made it quieterAlright, sounds like I will have to map out this bad boy and probably come back with more targeted questions about specific components.I was hoping those hair dryers would be pretty similar from one to the other or maybe we have some hair dryer engineer in this forum :-)Still, I appreciate your replies.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: October 10, 2024, 12:39:31 pm
content: Good Morning Gorman, The hair drier is designed and built for operation at 100 volts, and you are operating it at 125 volts, so the heater and fan are going to run 25% higher. I agree with the others that purchasing a drier designed for your voltage is the most logical option.

author: IanB
author_rank: Super Contributor
timestamp: October 10, 2024, 01:54:50 pm
content: As BILLPOD said, the supply voltage in Japan is 90-100 volts, while in North America the supply voltage is nominally 120 volts.So one thing you could do, is try to find a step-down transformer to convert 120 volts to 100 volts. This would have to be quite big though, rated at 1500 VA or so.

author: Terry Bites
author_rank: Super Contributor
timestamp: October 10, 2024, 02:43:13 pm
content: Buy a drier you do like?

author: MrAl
author_rank: Super Contributor
timestamp: October 10, 2024, 03:08:10 pm
content: Quote from: gorman2040 on October 10, 2024, 05:05:38 amHello,Simplest method probably is to get a variac. With that you can control the voltage getting to the hair dryer. You will need one that can handle the full power of the hair dryer. You do have to be a little careful though because even though a variac is a transformer (which is also variable) it is usually not isolated, although you could get one that is isolated at higher cost.You should still check for overheating though. The theoretical ratios for voltage and airflow are the same, but in practice there may be other factors which may slow down the fan to a lower value than expected but keep the heat higher than expected.

author: Xena E
author_rank: Frequent Contributor
timestamp: October 10, 2024, 04:45:54 pm
content: Variac would work well, however aranging a voltage bucking transformer would be cheaper option, the power handling of the buck transformer would only need to be the proportion of voltage dropped.You need someone local to you to help with that if you're not familiar with the technique.X

author: IanB
author_rank: Super Contributor
timestamp: October 10, 2024, 04:50:06 pm
content: Quote from: Xena E on October 10, 2024, 04:45:54 pmPeak load is 1300 W at 100 V, therefore 13 A.If using a 24 V bucking transformer, it would need to handle the 13 A, therefore 24 V x 13 A = 312 VA ?So a bucking transformer sized at about 300 VA should be suitable?

author: gorman2040
author_rank: Contributor
timestamp: October 10, 2024, 04:57:47 pm
content: Interestingly, I ran the hair dryer in Japan as well and it was still very loud and powerful. I honestly don't remember a noticeable difference running it in both countries but that's just what I noticed so no measurement really.Again, I very much like this one as it provide the 5 speed and heat settings which most hair dryer don't have unless they make "interesting math" in their marketing.I have previously tried a transformer for my older hair dryer to make it work in Canada whereas it was designed for the UK (230 to 120 transformer) but the transformer was actually louder than the hair dryer at the lower settings, some kind of vibration was happening, not sure if I got a crappy transformer but it was expensive! This ultimately proved useless as the dryer could just run slower on 120v and that was perfect.I'll look into the variac and voltage bucking transformer, thanks for the suggestion.I also see this as an opportunity to learn a few things and see how far I can get with this.I have a local electronic shop I could talk to if needed.Thanks all for your input.

author: Old Printer
author_rank: Frequent Contributor
timestamp: October 10, 2024, 05:53:14 pm
content: In the "old days" you might have found several hefty resistors and a rotary switch. Making some alterations would have been reasonably straight forward to someone with a good stock of basic components and knowledge. Looking at that board it is reasonable to assume fan speed and temp controls are likely managed by a microprocessor and some transistors, FET's etc. It also surprises many folks to learn that the window control button on your car door is not wired directly to the actuator, but is instead a type of encoder that sends a signal to a computer that then sends control current to the actuator. Not that it is practical, but is would probably be easier to start with a new microprocessor and control circuit and write your own code, than it would be to reprogram the one that is already in their. Maybe:)

author: Uunoctium
author_rank: Frequent Contributor
timestamp: October 10, 2024, 06:37:52 pm
content: tl;drPlease note that reducing the fan speed leads to a reduction in the air mass flow. If you do not limit the power of the heater coil at the same time, your output temperature will increase (dramatically).If you negate this problem, this becomes more a plan for converting a hairdryer to a heat gun.

author: gorman2040
author_rank: Contributor
timestamp: October 11, 2024, 03:01:42 am
content: I will take a look at the circuit board and try to have a basic diagram, there are a few basic components on it so I am hopeful they can influence the fan speed.I run this thing almost cold so the heat will stay in check

author: BILLPOD
author_rank: Frequent Contributor
timestamp: October 11, 2024, 12:47:41 pm
content: I just now remembered that I once opened one of these hair blowers/driers and found that the fan motor was 12 volts, and the heating element was wired in series with the fan motor.

author: Gyro
author_rank: Super Contributor
timestamp: October 11, 2024, 12:59:15 pm
content: Yes that is/was a quite common and efficient solution. A 4 discrete diode bridge on the back of a low voltage brushed DC fan motor in series with the element. The motor speed automatically varies with heating element current, ie. which tap is selected.

author: MrAl
author_rank: Super Contributor
timestamp: October 11, 2024, 03:48:39 pm
content: Quote from: gorman2040 on October 10, 2024, 04:57:47 pmHello again,Yeah unfortunately hair dryers make noise mostly because the fan has to run at high speed when it can only be an inch or two in diameter. If you could use a 250mm diameter fan it could run much quieter, but obviously that's too large to fit into a hair dryer. As you get smaller in fan diameter the speed has to be increased so you can get some reasonable air flow. This is the same with computer case fans. There would be a square law involved which means as you go larger in diameter you get much more air flow it is not linear with diameter (Area=pi*r^2 not area=pi*d). A heat gun makes quite a bit of noise also.This may be a hard problem to solve unless you don't mind a very slow air flow and less heat.I am not sure you can use a buck regular unless everything inside is run on DC. Most of this stuff runs on AC. However, you may be able to try a speed regulator made for power tools. That's like a light dimmer but can handle much higher power. They make this using a triac which regularly interrupts the current flow and that is how they reduce the power getting to the appliance or power tool.I would still say the variac is the simplest and must work without any hitch because they are made for AC and most things we plug into the wall run on AC. They also come with a plug on the outside so you just plug the appliance in. You can run all sorts of stuff with these things, even power tools that you want to slow down.Things I have used a variac on in the past:1. Heat gun (most relevant to this discussion).2. Angle grinder.3. Television for testing.4. Microwave oven to reduce cooking power without pulsing.5. High power converters for testing (1000 watts to 30000 watts with a higher power 3 phase variac).The price on these variacs have come down over the years which makes it more feasible now.

author: CaptDon
author_rank: Super Contributor
timestamp: October 11, 2024, 07:11:05 pm
content: No kids, the motor is not in series. Wouldn't 13 amps at 12 volts seem just a bit excessive? The motor is wired in parallel with a small portion of the heating element and it will include a bridge rectifier. I have seen selectable taps / speeds at about 5% tap and 10% tap. Also at the far end they have an arrangement where using the entire element has higher resistance, lower current and thus lower heat and a slower fan. For more heat they actually use a tap on the element using less of the element with a likewise lower resistance, more current, more heat and a faster fan speed. B.T.W. if the element goes open circuit across the part where the motor is tapped the motor almost instantly burns out!! The professional units have two motor taps for hi/lo fan and a triac control circuit for the entire element which allows control from about 40% to 100%. Why not less than 40%? Can't take a chance on the fan motor not spinning up at lower settings when switching on.

author: CaptDon
author_rank: Super Contributor
timestamp: October 11, 2024, 07:13:05 pm
content: Don't forget the crazy work around for fan only on the 'COOL' setting!!

author: Gyro
author_rank: Super Contributor
timestamp: October 11, 2024, 08:00:46 pm
content: Quote from: CaptDon on October 11, 2024, 07:11:05 pmOh yes, you're right. It was on a tap.

author: Zero999
author_rank: Super Contributor
timestamp: October 11, 2024, 09:44:19 pm
content: What sort of motor does it have? Can you please post a picture of it.Adding a resistor might do the job. I doubt it's that difficult to do, but it'll heat up more unless there's feedback, so be careful.

author: BeBuLamar
author_rank: Super Contributor
timestamp: October 13, 2024, 09:54:46 am
content: Now think about it I think most hair dryer has simple DC motor and not AC induction motor so controlling the speed is simply controlling the voltage fed to it.

author: gorman2040
author_rank: Contributor
timestamp: October 14, 2024, 08:57:49 pm
content: The motor is encased and I was a bit worried I would break something so I hope those pictures are enough.I know I might end up having to take those things apart but I'll do that once I am sure it is needed.There is a clearly marked grey wire for the motor, it splits into two of those black components with a grey ring on one side (diode?) and connect to each pole of the motor.Same for the other side of the motor's pole, two of those black components and then connect to the heating element.

author: gorman2040
author_rank: Contributor
timestamp: October 14, 2024, 09:03:22 pm
content: I also updated my first post with the two following things:I will mostly use the lower fan speed and heat, sort of a small heater.I don't need to keep the ION and hot/cold auto switch feature, if that helps modifying the hair dryer.

author: IanB
author_rank: Super Contributor
timestamp: October 14, 2024, 09:14:00 pm
content: Quote from: gorman2040 on October 14, 2024, 09:03:22 pmSorry to disappoint you, but there is really no way for anyone to help you make modifications to this unit from such a distance as this.The pictures you are posting cannot help. It would be like posting pictures of your car engine under the hood, and then asking someone to explain how you could replace the starter motor based on those pictures. You would need a workshop manual and experience as a mechanic to do such a job.Your best solution would be to say, "This cannot be modified. I should leave it alone."

author: Circlotron
author_rank: Super Contributor
timestamp: October 14, 2024, 11:05:08 pm
content: Quote from: IanB on October 14, 2024, 09:14:00 pmOnce upon a time cars and hair dryers were easy to fix. Not anymore, so it seems.

author: Xena E
author_rank: Frequent Contributor
timestamp: October 15, 2024, 07:41:35 pm
content: Quiet running (large fan, slow motor), moderate heat output is a feature of the 'Pifco Princess'.Now vintage they were very popular and almost indestructible. There are usually several examples available for sale, on EBay.I have an example from the 1970s, bought second hand, still in very good condition, for the same qualities that the op is looking for. It's biggest drawback is that it's a little heavy.There was a version of these that was sold in N America for use on 110–120VImage, from EBay.

author: BeBuLamar
author_rank: Super Contributor
timestamp: October 15, 2024, 10:04:50 pm
content: The motor looks like a DC motor and i think it runs at low voltage like 12DC or so.

author: gorman2040
author_rank: Contributor
timestamp: October 17, 2024, 03:44:47 am
content: Nice! I wish I could actually try hair dryers before buying. It was especially hard in Japan with the language barrier and they actually usually don't do return so I was stuck with itI noticed the lower wattage ones are usually a bit quieter which I hoped this one would be...

author: gorman2040
author_rank: Contributor
timestamp: November 18, 2024, 06:32:11 am
content: Hi,I'm getting back to this.Here is a few things I considered:Getting a dimmer or variac - I understand this is likely not compatible with brushless motors which is likely what this hairdryer hasGetting a step-down transformer - This looks more expensive than the haidryer and is likely not going to reduce the speed enough from 120 to 100 VI am not aware or other "plug'n'play" options but if you have any idea, let me know.I started mapping the circuit, starting from the easy side, which seems to be the heating element.I created a diagram that I share here. AC1 and AC2 are the two wires from the plug.I was wondering if I could add a resistor on the grey cable labelled "motor" to reduce the whole thing, heat and motor speed.What confuses me is how this thing can get 5 different heat and speed settings independently when they look like they are using the same "loop"

author: Xena E
author_rank: Frequent Contributor
timestamp: November 18, 2024, 08:06:48 am
content: Dropping the power to the heater/ motor circuit with a resistor:The resistor will just be dissipating the heat instead of the heating element!And it will be a big resistor.The electronics that runs the unit is probably already a phase angle type controller or 'dimmer' as you call it, trying to add another externally may have unexpected (unwelcome) results.QuoteReally? If your circuit is accurate I would have thought the fan would run at a discreet speed for each temperature setting? So a high heat setting would give a fast fan speed, lower setting lower speed.(Are you saying this is independently controlled?)Perhaps you have only noted the motor dropper section of the circuit?X

author: Zero999
author_rank: Super Contributor
timestamp: November 18, 2024, 08:25:07 am
content: Quote from: gorman2040 on November 18, 2024, 06:32:11 amWhat gives you that idea? Going from the photgraphs and your schematic it has a brushed DC motor, which work with a lamp dimmer or variac.

author: Gyro
author_rank: Super Contributor
timestamp: November 18, 2024, 10:24:37 am
content: Yes, the motor is brushed. Whether the rest of the dryer's electronics will behave as well is another matter though - I see a Holtek HT66f0xx MCU on the PCB photo in the OP. That may well not take kindly to either idea.I think I would be looking for a new hairdryer by now, rather that waiting until this one is trashed.

author: gorman2040
author_rank: Contributor
timestamp: November 21, 2024, 03:17:17 am
content: Quote from: Zero999 on November 18, 2024, 08:25:07 amI was looking at their other models and some say they have brushless, also seeing it is more costly/higher end than most hairdryer, I just assumed.I'll take your word for it.

author: gorman2040
author_rank: Contributor
timestamp: November 21, 2024, 03:33:35 am
content: Quote from: Xena E on November 18, 2024, 08:06:48 amThat is what I feared with the resistor, so it sounds like either there won't be enough room or might cause a heat hazard in the unit which doesn't sound great.You can indeed set the fan speed and heat with 4 up/down separate buttons, no idea how it works given the heating element and motor seems to use the same feed.There are those two capacitors, one between the two poles and one between one pole and the "frame" of the motor. I wonder how they influence the rest. Is it possible they could boost the speed of the fan?I also noticed the big round inductor is in line with that circuit as well as a transistor with only its two outer legs closing the circuit, the middle leg is cut.There are other components connected in parallel that goes to the LED, control buttons, on/off switch, hot/cold auto switch and ion feature. Obviously this adds a lot of complexity and the circuit tracks are too small for me to see how it connects.

author: gorman2040
author_rank: Contributor
timestamp: November 21, 2024, 03:36:52 am
content: Quote from: Gyro on November 18, 2024, 10:24:37 amUnderstood, I'm just sad to just lose my $80 without trying anything

author: Xena E
author_rank: Frequent Contributor
timestamp: November 21, 2024, 05:35:48 pm
content: Quote from: gorman2040 on November 21, 2024, 03:33:35 amWithout a circuit diagram I can't possibly speculate on your questions except to say those capacitors on the motor are there solely to reduce EMI and they perform no other function.It seems a so advanced unit that it looks to me that it will be impossible for you to hack.Sorry.X.

author: IanB
author_rank: Super Contributor
timestamp: November 21, 2024, 06:43:07 pm
content: I think if you use earplugs the blower will be a lot quieter. That would be a simple and cheap solution.

author: Gyro
author_rank: Super Contributor
timestamp: November 21, 2024, 08:13:50 pm
content: Quote from: gorman2040 on November 21, 2024, 03:36:52 amAt least you didn't fork out on a Dyson. You really would be spluttering about the cost then!

author: gorman2040
author_rank: Contributor
timestamp: November 22, 2024, 12:54:40 am
content: Thanks for confirming, that is what I read as well as increasing the torque, I believe. Definitely not going to help with my issueIt is clearly an over-engineered hairdryer

author: gorman2040
author_rank: Contributor
timestamp: November 22, 2024, 12:57:43 am
content: Lucky for me, I already knew Dyson is quite loud!I'm close to giving up but I'll see if I can do more reverse engineering. At least I am learning stuff.Thank you to everyone that took some time to reply, even the sarcastic answers

author: gorman2040
author_rank: Contributor
timestamp: November 22, 2024, 12:58:45 am
content: I recently found recordings of those hairdryers on Youtube!That will do it for the ambience

author: Zero999
author_rank: Super Contributor
timestamp: November 22, 2024, 09:44:27 am
content: If you just want a hair dryer with variable speed, then buy a cheap hair dryer, preferably single speed, and run it off a lamp dimmer. A cheap hair dryer will just have a DC motor with a bridge rectifier, in series with a heating element, which drops the voltage to the motor, as well as providing heat. It might have a low speed setting, which will just be a diode. If so, then bypass the diode or remove it, because it might not play nicely with the lamp dimmer.

author: gorman2040
author_rank: Contributor
timestamp: November 24, 2024, 05:13:29 am
content: Quote from: Zero999 on November 22, 2024, 09:44:27 amSounds like a good alternative, thanks for the suggestion!

author: gorman2040
author_rank: Contributor
timestamp: November 26, 2024, 04:53:31 pm
content: Quote from: Xena E on November 18, 2024, 08:06:48 amActually I was wrong about that. There is a slight variation of either fan speed or heat when respectively changing heat or speed setting but it is minor.I noticed one of the higher fan speed definitely increase the heat without me touching the heat setting.