Please explain this circuit to me of electric heating blanket

Thread Starter

Mrmoo

Joined Jan 23, 2021
4
Hello everyone. I am not a professional, but doing minor electrical, electronic stuff is my hobby and i really love it. I really enjoy understanding small circuits and repairing stuff which has minor issues.
I had three year education of electronic associate engineer. I did not take interest in college, but now i am really enjoying this.
I do have understanding of basic components but i might need more explanation.
I need your help in thoroughly understanding this circuit. This is a circuit of electric heating blanket. And i wish to create a diy blanket and circuit myself.
if possible please provide a diagram of this circuit and please explain. I will also need help how to check this circuitwith multimeter.
i know this might be alot to ask but i would appreciate your help. Here are the pics.
 

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jpanhalt

Joined Jan 18, 2008
11,088
Welcome to AAC.

Your pictures do not show enough to allow one to "reverse engineer" the circuit. One needs both the top and bottom of the board as well as any component labels, such as for the three legged device on the left side.

From a different perspective, an electric blanket needs a properly designed blanket. That is the expensive part and is probably something you cannot make. The control circuit is relatively trivial, but do you want to risk making such a potentially dangerous circuit with so little experience?

I suggest starting with lighting projects, such as LED lights, powered by batteries.
 

Dodgydave

Joined Jun 22, 2012
9,953
We need to see the reverse side and the markings on the T1 component .
Ideally it's not a good idea to make your own electric blanket..
 

Wolframore

Joined Jan 21, 2019
2,273
most likely an SCR “dimming” to control power to the heater, I would hope there are some safety circuits to make sure it doesn’t overheat, burn or cause fires.
 

DickCappels

Joined Aug 21, 2008
7,436
The real magic is in the blanket itself. It relies on the negative feed back as heat increases the blanket's resistance until it settles at a temperature as a function of voltage. Looking at some circuits on the interent, the temperature controller can be as simple as a triac light dimmer. As with many things that are in close contact with people and connect to the power mains to me this does not look like it would be safe as a DIY project for somebody starting out in electronics. I certainly not try it because I can imagine many weeks of trial and error and rebuilding prototypes with different materials go get it all right. Easier to save up and buy one.
 

Delta Prime

Joined Nov 15, 2019
1,014
I need your help in thoroughly understanding this circuit. This is a circuit of electric heating blanket. And i wish to create a diy blanket and circuit myself
Hello there :) satisfy all requested information above. This specific circuit you will thoroughly understand the operation of.
 

Thread Starter

Mrmoo

Joined Jan 23, 2021
4
The real magic is in the blanket itself. It relies on the negative feed back as heat increases the blanket's resistance until it settles at a temperature as a function of voltage. Looking at some circuits on the interent, the temperature controller can be as simple as a triac light dimmer. As with many things that are in close contact with people and connect to the power mains to me this does not look like it would be safe as a DIY project for somebody starting out in electronics. I certainly not try it because I can imagine many weeks of trial and error and rebuilding prototypes with different materials go get it all right. Easier to save up and buy one.
I just want to understand it. I wont be rebuilding it. Rather i just want to be able to find the errors in circuit when something does not work.
 

Thread Starter

Mrmoo

Joined Jan 23, 2021
4
D3999784-6A59-4C50-BD91-ECFF12245D45.jpegHere is picture from back, actually i should have uploaded it already.
now if possible please explain the circuit to me.
Secondly can you answer these questions.
What is the person who built this want output voltage and is that ac/dc if any then why ac or dc and why he needs that output voltage why not less or more.
Answer to these will help me why he needed this circuit. Thanks
 

Thread Starter

Mrmoo

Joined Jan 23, 2021
4
I would only diy when i am 100 percent confident. But at first i want to start by being able rectify the errors and understanding circuit.
 

Dodgydave

Joined Jun 22, 2012
9,953
View attachment 228665Here is picture from back, actually i should have uploaded it already.
now if possible please explain the circuit to me.
Secondly can you answer these questions.
What is the person who built this want output voltage and is that ac/dc if any then why ac or dc and why he needs that output voltage why not less or more.
Answer to these will help me why he needed this circuit. Thanks
That's an Holtek chip , it's a Microcontroller so you can't alter it.
 
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