2N2219A, 2N2221 and 2N2222A are silicon planar epitaxial NPN transistors in JEDEC TO-39 (for 2N2219A) and in JEDEC TO-18 (for 2N2222A) metal case. They are designed for high speed switching and small signal applications at collector current up to 500mA, and feature useful current gain over a wide range of collector current, low leakage currents and low saturation voltage.
NPN
{ Comments on this entry are closed }
What Test equipment should I have and what tools should I have on my workbench?
If you’re starting from scratch, there are a number of things you’ll need to have.
As far as test equipment, you need to have a good Voltmeter. Notice I didn’t say digital, I said “good”. So how do I define good? Well it needs to have a high input impedance. A bare minimum sensitivity of 20kΩ/volt, the higher the better. Most digital multimeters and VTVM (Vacuum tube volt meters) have an input impedance of 10MΩ. Note that since the input impedance is constant, the sensitivity will change depending on the voltage range chosen.
It would be nice to have two multi-meters when you’re working on power supplies and doing initial check on equipment. Seeing the current and voltage change can be very helpful. This is not essential to start and I would wait if you’re building up from scratch.
This is not essential to start with, but rather something you should keep your eye on. I have one that is almost 30yrs old now, which I’ve owned since it was new. Probably a basic thing to look for is 20MHz bandwidth and dual trace capability. Beyond that there are tons of features to look for and I could devote a whole set of articles t choosing a scope.
There are tons of options to choose from. Here is a good resource that you can use. I started with a 25Watt pencil iron and used that for many years. I even build a computer that involved soldering literally thousands of pads without a problem. This resource has several DIY options if you don’t want to spend the “big bucks.”
If you’re doing lots of troubleshooting, a de-soldering iron or at least an anti-static de-soldering pump are going to be key.
For testing power supplies, especially SMPS you will need a dummy load to properly test it. See this article on building your own.
As you do more and more testing, the ESR meter will become an essential tool in evaluating capacitors. It can quickly tell you whether a cap is good or bad. Additionally, since they do such a good job of measuring low resistances, they can help you find and identify cracks or breaks in PCB traces.
I suggest something that can provide 30 to 50 volts DC and somewhere between 3 to 10 Amps of current. A very useful and I would almost insist as essential is a current limiting capability. The reason is if you’re testing a suspect circuit, it is nice to prevent it from burning to a crisp by virtue of over current. Similarly, a high output current capability is key in some testing circumstances. (You may want to intentionally stress a circuit)
Another useful though certainly not essential for a beginning test bench is a frequency counter. I have a 500MHz capable unit with a high stability crystal reference oscillator. Some multi-meters have a frequency counting capability up to 10 or 20MHz. This will likely suffice for most requirements. I do a lot of work with radio transmitters and receivers so find the counter very helpful.
To summarize, the “good” multimeter is the first piece of test equipment you should focus on acquiring.
Good luck, let me know how it goes.
{ 0 comments }
