breadboard
I have just bought a breadboard, but I have notinced that the components are hard to insert into the holes (and sometimes only one pin go in and the another one go out, like a LED).
In videos I see people insert componenets into breadboard very easily.
Is it normal because it is a new breadboard?
Will it be fixed soon ?
Any way to make inserting compomemts easier?
I tried to use a jumber wire to help making holes bigger, but it didn't helped.
Here's a picture of a board which had some headers forced into it which were too large, damaging the contacts:
The outer rows of the Sharpie'd area make intermittent contact, so we avoid the whole section. Notice that some of the numbers are rubbed off, and also notice the burnt spot at the top of the picture where something burned up.
The breadboard still has two other middle sections, and this section is only 20 rows tall, so that leaves 172 good rows. On a university budget, that doesn't merit replacing the board. If you are demonstrating breadboarded circuits to a client, you should probably replace the whole thing.
By the way, this board is at least 8 years old, and still works fine except for the indicated area. I've only been around it for three years, but no one has had any problems with it that I've heard of.
Do not put 120VAC on a breadboard. While there's nothing preventing you from putting 120VAC on a beardboard, that's really dangerous so don't do that.
Get a perfboard to solder your relay in. Mount said perfboard with the relay into a plastic project enclosure box. That way, you won't accidentally short any of the relay contacts. Drill a hole in the box to allow for 120VAC connectors.
You can get all those items at your local Radio Shack or Fry's electronics. Or just about any electronics supply store.
According to your comments, you have a HSR412. You should still get a perfboard and plastic box and solder this device into it to protect it and to protect yourself and others from a potential shock. The datasheet says that it provides "4,000 VRMS Isolation", so w.r.t. isolation you should be fine.
The datasheet specifies that the control LED has a voltage drop of 1.6VDC @ 10mA. Assuming that your Arduino outputs 5VDC, you need a resistor in series with the LED to drop 3.4VDC while passing 10mA. This is to get the 5VDC down to 1.6VDC. You can use Ohm's Law (\$V = IR\$) to figure out the required resistance:
\$R = V/I = 3.4\text{ V} / 10\text{ mA} = 340\text{ }\Omega\$.
There isn't actually a resistor that's exactly 340 ohms, so select a 390-ohm resistor. Now, calculate the power across the 390-ohm resistor:
\$P = IV = I^2R = (10\text{ mA})^2(390\text{ }\Omega) = 0.039\text{ W}\$.
So a 390-ohm, 1/8 watt resistor connected in series with the LED should be appropriate. So you can connect your Arduino to your relay like this:
Arduino HSR412
----------------+ +----------
| 390 Ohm 1 |
control pin +-------/\/\/\/-------+----+
| 1/8 Watt | _|_
| | _\_/_
| 2 | |
| +-------+----+
| __|__ |
| ___ |
| _ |
| |
The maximum pin source current from an Arduino is 40mA per pin IIRC, so you should be able to just drive the LED and resistor directly. Again, it's best to put your relay in a plastic enclosure to protect yourself from the 120VAC that will be present.
Best Answer
I have had this happen to me and it was essentially a faulty breadboard. The components should easily go in and out if the breadboard is good. I have managed to loosen up my bad breadboards by forcing large tough component legs(like pin header) into and out of the stiff holes repeatedly, they eventually become more accepting of parts.
If it is really bad you may just need another breadboard.