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What are these electric components? Answered

Hello guys I thought you could help me out with this a little bit.
So I went to the dollar store looking for some. I'd like hack some to what I want, but first I need to know how it works!

Um want to know what these things are on the board and what it is.

So, I want to know what that black blob is on PCB and also that barrel shaped thing and why is the siren hooked up to that barrel.

Thanks guys!


What is the thing from the $ store and why did you choose to it?


It's a window magnet alarm. Pretty cool you get a siren, magnet switch (NC), 3 LR44 button cell batteries all for one buck.

I'd have the (piezo?) siren & switch. The rest probably isn't much use unless you've an idea for something with magnets.



5 years ago

The black blob is called a "chip-on-board." It's essentially an integrated circuit (IC) that is glued directly to the board instead of being inside a plastic case with multiple pins coming out to make the connections. The 'black blob' is the glue that holds it there and protects it. I can't tell exactly what it is that you have there, but since you called it a siren I'll guess that the IC contains the data that generates whatever sounds it makes.

The 'barrel' is a resistor, probably the most commonly used electronic component. In this situation it is probably used to limit the current to the siren. Resistors have many, MANY other applications as well. It's way too much to go into on a forum post.

Try google-ing 'basic electronics tutorial' or something similar and start reading... A LOT.

Hey mofoyaI know what a resistor is- I'm not talking about that. I'm not that basic! Haha, I was talking about the big black barrel shaped thing at the top of the PCB.

If I didn't know that was a resistor I wouldn't have an instructable. If you think I'm that basic go ahead and watch it here- https://www.instructables.com/id/DIY-headlights-and-turn-signals-on-your-RC-car/

You don't need to prove how "not basic" you are.  I was just trying to be helpful with the tiny amount of information given in the OP.  

About the resistor thing... I just missed the ball.  I thought that's what you were talking about being barrel shaped.

Anyway, no big deal, you got your answers either way.  Good luck with whatever your going to do with that thing...

Haha thanks! I guess I should be a little more descriptive in the future! Hey thanks anyways!

Mofoya, "Try google-ing 'basic electronics tutorial' or something similar and start reading... A LOT."

I like it :P

The resistor is the item with the colored stripes on it. As steve said the black barrel looking thing is an inductor.

yeah, i was unclear about what was being referred to as a "barrel shaped thing."

Oh yeah sorry I forgot to but in "black" so you guys don't think I don't know what a resistor is. LOL

The barrel thing is actually an inductor - a coil of wire on a magnetic core.

I read a little bit about that but could you possibly give me a quick overview of what it does or a good link for beginners?

An inductor is a component whose resistance to AC increases with frequency. A capacitor is a component whose resistance to AC DECREASES with frequency.

Inductors work using the magnetic field around them, capacitors use the electric field.

Haha thanks guys. Hey lemonie it's a window alarm. Yeah mPilch, I know what the resistor is, I just didn't know what the my water barrel was. I'm assuming its and inductor coil like mPilch said.

I can see a coil (the black barrel-thing), a resistor (the color-ring-thing in the middle of the 2 blank wires), a Chip-on-board (The black blob on the green thing), a PCB or printed circuit board (the green, flat thing), a switch (the thing with the black knob to the lower right of the image), a wire (Brownish long thing) and a case (the gray big thing where all the other things are in).
If you turn the PCB, more things would come into sight like a battery-holder and i think at least one additional component according to the 2 solderpads on the top.

It is impossible to say what they do since the chip-on-board is a custom made thing and without knowing the intended function and some proper measurements: No dice, pal.