Good transistors to have in my kit?

I want to order some kits with random useful set with good transistors and mosfets for random Arduino projects in SOT-23 package for SMD use.

I allready have the old trusty BC547 and BC337 as TO-92 package, but i want similiar transistors in the sot-23 package.

Som pnp transistors is also great to have, but NPN is what i use the most.

I have allerade ordered 1206 capacitor and resitor sample books.

Som ideas for good kits?

I use these.
Go thru this PDF for N and P channel logic level SMD MOSFETs:

I like the SMD 45V 0.5A SOT23 BC807 for a PNP.

Thank you very mutch LarryD :slight_smile:

Is it better to use an mosfet than transistor like BC337/BC547 etc.? I know that mosfets are more expensive, but not mutch....

For audio, I recommend MMBT9014 and MMBT9015 because of good noise performance and low cost, wide availability.

There is no "better to use a MOSFET" for every circuit, just most. Sometimes you really do need a BJT.

The problem you can run into with MOSFETs is they require a gate voltage of a certain level for them to fully turn on.
This is why we often say use a logic level MOSFET when 5v Arduinos are involved.
When it comes to a 3.3v Arduino, there are fewer MOSFETs that fit this bill.

BJTs require current (not a voltage) to switch.
Often a BJT is used as a front end switch for a MOSFET if the MOSFET is a 5v logic level transistor.

MOSSFETs are quite affordable, the AO3401 SOT23 is about $5.00 for 100 pieces on

Thanks guys :slight_smile:

But when i search on example AO3401 and see the picture of the mosfet i see an another number on it. Is this normal?

I use IRLML6402 MOSFETs for high side switching\powering of stuff like GPS, Radio modules etc on 3.3V Arduinos and they work fine, even the real cheap ones on Aliexpress.

That’s normal.

My AO3401 MOSFETs have A19T written on them.




Thanks alot srnet and LarryD :slight_smile:

The superbeta, very low saturation voltage ZXTN2018 and ZXTP2027 are handy, 5A/-4A rating and happen to be ultra-ultra-low voltage noise too. They are the surface mount equivalents for ZTX851 and ZTX951 (eline package).

Thanks for tips LarryD :slight_smile:

Have made my self som breakouts now. New chipment is soon on my way from China :slight_smile:

Looks like you are having fun :slight_smile:

I was going to make a version too.

Was going to add a pull down and series gate option (cuttable trace) to the PCB.

Yes, i do this just for fun. :slight_smile:

Good idea. Maybe an gate pull down with an jumper switch?

What are you going to do regards to the series resistor?

Something like this?

No resistor, no pulldown, or add an resistor with the wanted value.

I think that with a cutting trace you can't redo it. With a resistor like that you can... ?

Or something like that:
Just bridge the solder pads (if resistor is added) for adding pulldown.

Something like this:

The gate series resistor could have a cut trace under it so a 0 ohm resistor doesn't need to be added if desired.

Might want thicker traces on source and drain!

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I just received a chipment myself, some TM1668's. :slight_smile: