Electrical Components Help

Thread Starter


Joined Apr 26, 2006
Hello everyone, I was wondering if there were any live chat or IRC channels anyone knew of for newbies looking for information on electrical components. I've recently gotten into electronics and I have a box full of all kinds of components, many of which I have no idea what they are or do. Most I've been able to learn about by googling around but there are a few that I haven't been able to find and I am getting a little tired of just web searching all the time. I'm sure someone who has expertise on these things could tell me about them in no time :)

Thanks for any help anybody can provide!

Here's the latest thing I was looking for, if anyone recognizes it. I got as far as it's a 3 lead LED, but I'm not sure what the black casing around it is for or how much power it can take, etc. There are no letters/numbers/markings of any kind on it.



Joined Feb 24, 2006
The black cylinder is just a spacer. When you mount the LED to a circuit board the actual light emitting part is above the board by 3/8 ths to 1/2 inch.

It is common for a three lead device to be a bicolor LED. You can use a multimeter to see if the device is common cathode or common anode.

LED currents will be in the range of 2 mA to 30 mA. A resistor in series with the LED will control the current and determine the brightness. Start with 2 mA to see if there is light. If it is too dim try a smaller resistor. Read the tutorials on this forum for how to select a resistor for lighting a LED.


Joined Jan 28, 2005
To add further weight to papabravo's excellent reply, here is a datasheet for just such a spacer. Of course these spacers can be purchased in varying lengths to permit you to set your LED off the board by the height that fits your specific design needs.

LED spacer datasheet



Joined Apr 27, 2006
From the pic, it most definently looks like a Bi-LED. Cathode is the center pin (Negative) and the two outer pins are anodes (Positive).

How can I tell this? Over the many years I have messed with LEDs, I found a neat Trick to find the cathodes of LEDs - When you look inside the LED at the leads that are in the plastic, the cathode always is the one that has the biggest area. In your picture, the center pin has the most area, so it's the cathode.

This trick has never failed on me. Yes, there are other things that Identify the cathode (sometimes anode), but these are not consistant on LEDs, because different manufactures see things differently, so they do things thier way.

Also, LEDs can be tricky. Some emit light, and are used as indicators, etc. Some don't emit light, they emit Infared. I.E. remotes controls for TVs, VCRS, DVD players, etc use Infared LEDs to transmit signals. But these LEDs sometimes look just like a Light emitting LED. Some are Infared Recievers, and there are other things as well.

To do a quick test to light it up, the easiest is to get 2 1.5 volt batteries, a 180 to 470 ohm resistor, some wires, and hook them all in a series circuit (Basically a chain) as shown below:

( B )-----[(-)||||||||(+)]---------[(-)||||||||(+)]------Resistor----( A )

Points A and B are you supply voltage. B to the center pin of the LED, and A can be touched to either one of the outisde pins. If one pin is Red light, and one pin is Green light, then if you touch both, then you will get a yellowish (Amber).

Yes, there is a way to calculate the proper resistor to get the proper current (2milliamps to 20milliamps, sometimes 30 or more), but for most LEDs, 3 volts and 330 ohm resistor means about 2-5ma is drawn.

I say most, because there are special LEDs, such as high intensity, Blue colour LEDs, and etc, that are either higher voltage or higher current, but for the part's bucket, it is simple enough to just use this setup.

Besides, 180/330/470, and even 1k resistors are very common values for current limiters to LEDs inside consumer products.

It's great to see that you have taken an interest in electronics. But I forewarn you, it's not something that can be learned overnight, or even several months.

My passion started when I was 2, and I, just like you are doing, learned a lot on my own, buy reading, observing, dismantling, and etc.

If you really don't know much at all about electronics, I highly suggest that you go to Radioshack (or other electronic suppliers) and they sell "Electronic Expirements" kits, that have 50 or more expirements. As kid like as it might seem, they really did help me, my first one was in 5th grade. You will learn a lot about basic components, how they work, and simple, but effective circuits, that you can use later in your electronics hobby as building blocks to create even more complex circuits, because that is what electronics is, many small circuits working together to function as one complex one.

I now have 4 years of EET (Electronics Engineering Technology) under my belt, and even with 4 years of schooling and many years of personal experience, I still don't know some things, but that is also part of electronics, the learning never ends, and no one person knows everything.

I better stop rambling on, as I could go on and on :)

If you have any questions on this or any electronics, feel free to ask me.