Electronic – “Standard” components…


In class we are designing a few different circuits and it uses some diodes and opamps. Everything is fine on paper and everything makes sense. These are only ever refereed to as a "diode" or "opamp".

So then I made a simulation on pspice. However depending on what diode or opamp I choose the results I got were completely different. There where many opamps and diodes to choose from in the component list.

Until now I just thought a diode is a diode or opamp is an opamp as there's never been any more specifics on them. Nothing like a resistor or capacitor where you have to choose the correct value component to get it all to work.

So I was wondering when people say "use an opamp" is there a standard common / specific opamp that is the general one used.

Same with the diodes. Is there a standard go to diode that is used in all circumstances ..unless otherwise stated.

After thinking about it..what about transistors also?

Best Answer

Here are the types I immediately think of when someone says "diode", "op-amp", ...

  • Op-amp : LM741. The first "easy to use" op-amp IC on the market.
  • Diode : 1N4001. General purpose silicon diode good up to 50V blocking voltage and 1 amp current. The 1N4002, 1N4003, etc. are similar diodes with higher voltage ratings.
  • Transistor: 2N2222. NPN bipolar junction transistor. The 2N2907 is apparently the PNP equivalent.
  • (Linear) Voltage regulator : LM78xx series, i.e. the LM7805 for 5 V, the LM7812 for 12 V.
  • Digital logic, i.e. NAND gates and so on: 7400 series and 4000 series.

These are extremely common, basic parts. If you walked into a hobby store and asked for a hundred transistors, without specifying anything else, you would probably get a bag of 2N2222's.

This is not to say these parts are useful for everything - they have limitations on voltage, current, speed, accuracy, and so forth. But if you have to pick a type of component for the purposes of a SPICE simulation, these will work fine.

Edit: For reference, here are the "default parts" you get in CircuitLab:

  • Op-amp TL081
  • Diode 1N4148
  • Zener diode 1N4733A
  • NPN BJT 2N3904
  • PNP BJT 2N3906
  • N-channel MOSFET IRF530
  • P-channel MOSFET IRF9530
  • N-channel JFET J310
  • P-channel JFET J271