Which Transistors to get for a Beginner?

Hey there,

I am just starting out with electronics and need some advice for some components. I got myself a basics electronic set with a breadbord, some jumpers, leds, resitors and only small 0.1A transisitors.

So back to the question. What are usefull values/kinds especially for/of transistor to buy. I dont want to run to the electronic store every time I need something for a project.

I got the Tip31 for Led-Strip and small DC Motor control on my list. Are there (other) allround transisitors, maybe pnp's to get?

What things else are nice to have as an beginner? I really appreciate any tips.

That's hard to say.... The TIP31 looks like a good all-round choice. Its PNP compliment is the TIP32, but 90% of the time when you are working with just a positive power supply you'll be using NPNs.

Maybe just pick-up a couple extra TIP31s until you have a specific need for something else...

The most critical specs will be the current rating (collector current) and the power rating.* Almost any transistor can handle the low voltages (say 5V or 24V) that we are working with. The other specs (such as gain) don't vary that much from transistor-to-transistor so we usually don't worry too much about those other specs/characteristics (especially in digital circuits) . ...So in most cases, you'd "pick any-old transistor rated for 1 Amp or more", or something like that. ...But, it's tricky for a beginner because you don't know what specs you can ignore and what specs are important for a particular application.

The NPN [u]TIP120[/u] (and it's PNP compliment, the TIP125) is very popular. It's actually not a single transistor, but a Darlington pair in one package (with a couple of other components). A Darlington behaves pretty-much like a regular transistor with higher beta (higher current gain), and about twice the base-emitter voltage.

...I've been playing around with electronics for many years, and I can't remember the last time I used a transistor on a home project! I've got a few boxes of spare parts... I keep a good selection of resistors, capacitors, voltage regulators, LEDs, 1N4007 diodes, op-amps, and maybe a few other things I like to keep "in stock".

Then, I've got lots of "random" ICs and connectors and things from previous projects (because I almost always buy extra parts) and I've probably got a few transistors somewhere, but it's not something I intentionally keep on-hand.

  • You have to be careful with these ratings... If you are using the transitor near its maximum wattage rating (in linear non-switching applications), you'll need a BIG heatsink.. And, the maximum current rating rating ONLY applies when the transistor is in saturation (fully-on).

With the Arduino, we are usually using the transistor in switching mode (fully-on or fully-off) so power & heat are usually not big worries.

You gonna run to the electronic store every time you need something for a project... That just how it is ::) Could you try more with 5V? that is safer for the Arduino. For exampe a servo motor, relays, or a solid state relay, sensors, and so on.

2n2222 and it's pnp equiv handle around 600ma and they come in bags full for a couple of bucks.

They come in handy for driving LEDs and general purpose use..

If you are placing an order, add a few 2N7000 MOSFETs. They will come in useful one day, believe me!

Apart from that I echo cjdelphi, 2N2222 are cheap and cheerful and multipurpose.

dannable: If you are placing an order, add a few 2N7000 MOSFETs. They will come in useful one day, believe me!

Apart from that I echo cjdelphi, 2N2222 are cheap and cheerful and multipurpose.

These are penny parts. On these parts, go big or go home, otherwise all you are paying for is shipping. Buy by the 100s, seriously.

http://www.ebay.com/itm/100pcs-2N2222-TO-92-NPN-40V-0-8A-Transistor-/280891198552 http://www.ebay.com/itm/100pcs-2N7000-MOSFET-N-CH-60V-200MA-TO-92-NEW-GOOD-QUALITY-TO1-/300902221987

Here, I just put this together from Tayda, which is a cheap and very reliable hobby parts dealer, at least it is in the U.S. They've never let me down. They have all the parts discussed so far except the TIP 125, but they have the TIP 107 which is a very close, but actually better, part. Oh, I put the 2N3904 on instead of the 2N2222. This causes no end of discussions here, but for most applications the 2N3904 is usually just fine.


2N3904 - 2 cents, buy 100 $2.00 2N3906 - 2 cents, buy 50 $1.00 2N7000 - 9 cents, buy 50 = $4.50 TIP31C - 31 cents, buy 20 $6.20 TIP32C - 27 cents, buy 10 $2.70 TIP120 - 24 cents, buy 10 $2.40 TIP107 - 55 cents, buy 5 = $2.75

Don't buy any Darlingtons at all. [Though by some account the TIP120 may be "very popular", by the same token so are chlamydia and HPV, but should nevertheless be avoided, anathema. ]

Thanks everybody. I have some nice suggestions to go from here!

Also get some low power mosfets.

What you need is a logic level gate mosfet. The gate needs to be fully on or the resistance of the drain/source is not at its least so causes heat. My favourite small mosfet is NTD5867NL. It works with 5v on the gate and handles a few amps with ease. They are cheap. I bought mine from RS Components. There are others but make sure they are fully on at 5v on the gate.

ONLY buy a mixed bag of transistors and read up on taking measurements from them with a multimeter. carry this out for a number of them from the mixed lot and bag them up, writing on the bag the values you get from the multimeter readout. make sure you have it sitting in the right slots for that type of transisistor.

Get a collection of electronic throw outs and harvest it for capacitors, quartz oscillators,and MOSFETS. MOSFETS are expensive buggers so its worthwhile. You will get everything up to a 900 V n-drive mosfet from the power supply circuit of a standard PC, which can be used for fun stuff. after i get rid of stupid habits that is. ie stay below 12 VDC in the muck around stage and dont move up for a good amount of learning.

Unless you are aiming at analog electronics, I second the vote for logic-level power MOSFETs.

Darlingtons are poor performers, however they are available in sets of 8 in one package (ULN2803) which has a lot going for it for some applications (don't expect much current handling though, thermal issues always dominate with darlingtons).

And even for analog electronics rail-rail op-amps are more useful than bipolar transistors for many uses.

I can’t remember the last time I used a transistor on a home project!

This surprises me. I’m wondering how often you just bung another IC on the board when a simple transistor is all that’s required? Not that it does any harm if you have them to hand.