Ok, here's what I'm trying to do...

I'm building a homebrew fresh air device, and need to install a switch in this simple hairdryer that will switch off the heating elements. If there's anyway to do it, this would be cheaper than having to buy a blower.

I've opened the thing up, followed the wires, and drawn the schematic (below) from what I see. Could anyone explain to me how this thing works? Where in the circuit to install a switch?

 

Cant quite make out that switch you got drawn there. But you may be able to put another switch in just to turn on the motor and bypass the heater elements.

By the way, blow dryers are not designed for continual use. I'll bet If you run the thing for 1 hour straight it will burn up the motor, even without the heater elements on.

 

The switch that is already installed is essentially a double pole, triple throw slide switch that connects only two adjacent contacts in each row at a time (on each the two poles simultaneously). For example, if the contacts were numbered 1-4 (pole 1), 5-8 (pole 2), then when switch is in the left most of the 3 possible positions, contact 1 would be connected to 2, and 5 would be connected to 6. The middle possition is OFF.

 

Still, why would you be useing a hair dryer for freshair? Use a fan or open a window.

 

Dear Stephen,

From the looks of the ckt. diag., the heater elements have a dual role, as in it acts as a current limiting resistor in series with the DC motor which I presume must be rated at approx. about 3VDC. Hence,in my opinion, if the heaters are bypassed, then 120VAC will directly feed the rectifier ckt. and burn out the motor.

Regards,
Shahvir

 

Because that is the only way I have of getting the air blown into the 1 1/4" I.D. clear tubing.

 

Dear Stephen,

From the looks of the ckt. diag., the heater elements have a dual role, as in it acts as a current limiting resistor in series with the DC motor which I presume must be rated at approx. about 3VDC. Hence,in my opinion, if the heaters are bypassed, then 120VAC will directly feed the rectifier ckt. and burn out the motor.

Regards,
Shahvir

Is there way to substitue another resistance in place of the heaters?

 

Is there way to substitue another resistance in place of the heaters?

Yes, but the resistance should not come in contact with the air blast from the dryer fan as it will then heat up the air again defeating your purpose.

You can also go for an inductor or a capacitor of suitable rating for current limiting purpose on AC side, i.e before the rectifier section. It has an added advantage in that it does not emit heat as compared to the series resistance. However, the design of current limiting components should be of suitable rating or else it could pose a severe electrical hazard and safety issue!

Regards,
Shahvir

 

Yes, but the resistance should not come in contact with the air blast from the dryer fan as it will then heat up the air again defeating your purpose.

You can also go for an inductor or a capacitor of suitable rating for current limiting purpose on AC side, i.e before the rectifier section. It has an added advantage in that it does not emit heat as compared to the series resistance. However, the design of current limiting components should be of suitable rating or else it could pose a severe electrical hazard and safety issue!

Regards,
Shahvir

Thanks! I like your suggestion. I 'll have to think on this a while to understand it.

 

Or use a 3 VDCwall transformer

 

use a shop vac open up the blower port on the back....

 

Because that is the only way I have of getting the air blown into the 1 1/4" I.D. clear tubing.

What on earth do you need fresh air blowing in a 1 1/4" tube for?

Underground tunneling?

Prisoner in a box in the crawl space?

Clandestine grow lab?

Home style airplane seating?

Really big party balloons?

 

What on earth do you need fresh air blowing in a 1 1/4" tube for?

Underground tunneling?

Prisoner in a box in the crawl space?

Clandestine grow lab?

Home style airplane seating?

Really big party balloons?

Heh, now you've got me curious as well

 

And another thing, why does the tubing need to be clear?

 

Or use a 3 VDCwall transformer

Excellent idea! but again the transormer voltage and current ratings will have to match that of the motor. If motor is considered to be rated at 3VDC, then Xmer should be of lower secondary output voltage as after rectification the DC voltage across the motor is equal to the peak value of Xmer sec. RMS AC voltage. Gud Luck

Regards,
Shahvir

 

What on earth do you need fresh air blowing in a 1 1/4" tube for?

I know this is going to sound rediculous, but I need the fresh air blowing into the 50 or 100 foot long tube from that distance away where fresh air exists. I use a plastic tank fitting to connect the exhaust end of the tube to a clear PVC vinyl bag. I will first crank up the air flow coming thru the tube and into the bag. After plenty of airflow exist, I will then use it to put bag over my head to supply plenty of fresh air to my lungs while I work with ferric cloride so that I will no longer have to breath the fumes that have damaged my lungs in the past when making PCBs and from not having this fresh air device. I also need it for paint jobs with acetone, toluene, etc.

Oh, and just in case you're wondering, I will NOT sufficate because the device always keeps fresh air coming!!!

 

use a shop vac open up the blower port on the back....

I think this is a much better option then, keeping in mind the air quantity required

 

What on earth do you need fresh air blowing in a 1 1/4" tube for?

I know this is going to sound rediculous, but I need the fresh air blowing into the 50 or 100 foot long tube from that distance away where fresh air exists. I use a plastic tank fitting to connect the exhaust end of the tube to a clear PVC vinyl bag. I will first crank up the air flow coming thru the tube and into the bag. After plenty of airflow exist, I will then use it to put bag over my head to supply plenty of fresh air to my lungs while I work with ferric cloride so that I will no longer have to breath the fumes that have damaged my lungs in the past when making PCBs and from not having this fresh air device. I also need it for paint jobs with acetone, toluene, etc.

Oh, and just in case you're wondering, I will NOT sufficate because the device always keeps fresh air coming!!!

I would not recommend this as a method for critical apparatus. You should use approved methods for hazardous environments. Whenever anyone uses the words "always and never" things invariably go horribly wrong. Please reconsider what you are doing for your own safety.

 

I would not recommend this as a method for critical apparatus. You should use approved methods for hazardous environments. Whenever anyone uses the words "always and never" things invariably go horribly wrong. Please reconsider what you are doing for your own safety.

I absolutely agree with this advice. Safety should always be the utmost priority!

 

I think this is a much better option then, keeping in mind the air quantity required

If you agree with me, then what is this about?