Go Down

Topic: Transistor (Read 1 time) previous topic - next topic

Grumpy_Mike

Quote
Will the next battery be enough for me

https://www.aliexpress.com/item/UNITEK-USB-9V-rechargeable-lithium-ion-battery-1200mAh-6F22-li-ion-cell-for-wireless-microphone-Guitar/32822609362.html
No.

Quote
so for my purpose I can use five heaters with a power of 10W.
That is 50W, this requires a current of about 5.5A. That looks way too much for that battery, even if it was not then at 1.2Ah it would last at the most 13 minuets and probably not more than 8 or 9 minuets in practice.

I would have thought 50W in a glove is way too much. What is the purpose of this glove? It makes a big difference. My 50W soldering iron is quite big, you can solder with a 25W iron or even a 15W one.

Liz0905

What are the gloves to be used for - I suspect that the insulation is as important as the heat source.
I want to measure the temperature of a finger and warm it if the temperature falls below a certain threshold

Liz0905

No.
That is 50W, this requires a current of about 5.5A. That looks way too much for that battery, even if it was not then at 1.2Ah it would last at the most 13 minuets and probably not more than 8 or 9 minuets in practice.

I would have thought 50W in a glove is way too much. What is the purpose of this glove? It makes a big difference. My 50W soldering iron is quite big, you can solder with a 25W iron or even a 15W one.
ok i got it. what about those:

https://www.ebay.com/itm/PTC-heating-element-60-1-2-5W-12V-consistant-temperature-ceramic-Thermostatic-/152897933551

JohnRob

Hi,

The
Quote
https://www.ebay.com/itm/PTC-heating-element-60-1-2-5W-12V-consistant-temperature-ceramic-Thermostatic-/152897933551
is designed to always be at 60 °C, much too hot for skin.

I did some work with PTC heaters a few years back and they are great for constant temperature, however I've not seen any where the transition (control) temperature is low enough to be useful for contact with humans.


I've not been following closely but have you looked at flat silicone heaters?




Please do not PM me with thread based messages.  If your thoughts are worth responding,  the group should benefit from your insight.

Liz0905

Hi,

The  is designed to always be at 60 °C, much too hot for skin.

I did some work with PTC heaters a few years back and they are great for constant temperature, however I've not seen any where the transition (control) temperature is low enough to be useful for contact with humans.


I've not been following closely but have you looked at flat silicone heaters?





Because I'm really new to the whole thing, I did not even know which way to look

JohnRob

HI,

This is not the place you would normally purchase a flat heater but it gives you an idea.

Silocone heaters


They could also be flat Kapton heaters.


For a practical understanding of watts and heat look for one of these "GE 4-Watt Nightlight Incandescent Light Bulb".   You can hold it in your hand and get a "feel" of what 4 watts will be like.

Please do not PM me with thread based messages.  If your thoughts are worth responding,  the group should benefit from your insight.

allanhurst

I guess that these heated gloves might be for a motorcycle.

In which case there is no power supply problem.

Commercial products are freely available - why not investigate these?

Allan

Liz0905

I guess that these heated gloves might be for a motorcycle.

In which case there is no power supply problem.

Commercial products are freely available - why not investigate these?

Allan
The project is part of my studies and one of the goals is to create something that does not exist something that is exactly the same

allanhurst

Quote
create something that does not exist something that is exactly the same
??

They do exist, and have been developed over many years.

Do you have a much better approach?

A


Liz0905

??

They do exist, and have been developed over many years.

Do you have a much better approach?

A


Of course they exist and I studied them, the goal is to use components that are not used in warming gloves available in the market

allanhurst

#40
Feb 24, 2018, 12:49 pm Last Edit: Feb 24, 2018, 12:57 pm by allanhurst
All such gloves use resistive elements of some sort - normally NiChrome wire, but any power dissipating element would do ..... 

eg a Pentium processor.

NiCr is cheap and effective.

For temperature sensing a thermistor is the obvious device.


Allan

ChrisTenone

Quote from: allanhurst
... eg a Pentium processor.
Cool! You could recycle old, unwanted computers as hand warmers.

Quote from: allanhurst
... For temperature sensing a thermistor is the obvious device.
Wouldn't a device like a TMP36 (such as this one) be even simpler to use?
I'm not disparaging the differently abled. It's just that thirty years of community college has literally made me mentally retarded.

allanhurst

#42
Feb 24, 2018, 04:10 pm Last Edit: Feb 24, 2018, 04:15 pm by allanhurst
TMP36...

Sure,

There's a hundred ways to skin a cat.

I bought 100 10k thermistors for £1.  Though I don't intend to control 50 pairs of gloves.

You don't need an arduino for this job - a simple bit of analog will do.

Ramp generator ( 555? ) , comparator , reference volts source.and power switch device

Allan

ChrisTenone

Of course you are correct - that would certainly be the most cost-efficient to build heated gloves. But that isn't the theme here. It seems our OP wants to make something DIY with parts on hand. And Arduino control has easy appeal. But with 50-250 watts of power inside an insulated glove, I wonder what it's actual use would be.
I'm not disparaging the differently abled. It's just that thirty years of community college has literally made me mentally retarded.

allanhurst

The ancient LM10, designed by Bob Widlar, would be ideal for this job.....

but I share your puzzlement over the application.


Any help.OP?


Allan

Go Up