reviving a simply old thread
https://forum.allaboutcircuits.com/threads/drive-mosfet-with-3-3v-minimal-component-count.180559/

the circuit from @crutschow is well thought out
https://forum.allaboutcircuits.com/...v-minimal-component-count.180559/post-1649871

The idea is that many 'common' boards (e.g. stm32f103 'blue pill' and various 3.3v ARM mcu boards) are powered from 5v usb and use a 3.3v ldo to get vdd 3v3

I reworked that slightly to look like such, the mosfet is a 2n7000
https://www.onsemi.com/download/data-sheet/pdf/nds7002a-d.pdf
I got a little paranoid about this little plastic mosfet which spec a max Idrain of 200mA for 2n7000 and 100ma for 2n7002, so I placed a 5 ohm resistor at the source, I'm not sure if that'd help. But an idea is that I may 'go beyond spec' and use this say to drive a small motor which may possibly consume up to 100s of mA to perhaps 1A.
The Rds(on) at Vgs ~ 4.5v is given around 2 ohms, so just let say vcc 5v is 'shorted' across mosfet to GND that makes about 7ohm and currents = v / r = 5 / 7 ~ 710 mA, but that is v ^ 2 / r = 5 x 5 / 7 ~ 3.5 watts ! (it would probably 'melt' well, grin).

2n7000 is 'well known' to be a lousy mosfet , to switch on 3.3v gpio, with the spec sheet saying that.
Vgs(th) (Vds = Vgs , Id = 1mA ), = 2.1 - 3v (meh)
hardly very exciting to drive with 3.3v gpio
hence this circuit, which benefits from using the 5v supply common on 'common' mcu boards to get a better Vgs.



note that there is a *catch* in this circuit, the gpio needs to be operated in "open collector" mode, one should not drive the gpio high regardless, or you may get a short circuit at the NPN transistor

The next thing is I try to 'fit' this in a small 'footprint' as is possible.
I tried 'squeezing' it in 0.1" (2.54mm) perfboard, DIP 8 (7.62mm x 7.62mm) 'footprint' failed. Not unless I do a 'real' pcb, but the pieces are too 'fat' to fit a dip8 sized perfboard. like such:
https://www.aliexpress.com/w/wholesale-5x7-paper-pcb.html

laid out on a perf board as like above looks like this

I used 0805 smd resistors while the 2 transistors are through-hole parts, this current pcb (design) fits in a 5 x 5 grid (0.1"(2.54mm) perfboard.
About 25mm x 25mm including the edge cuts.

well, these days, I'd guess the 'easier' way is to use logic level mosfets, that can operate at 3.3v logic levels
https://www.aosmd.com/sites/default/files/res/datasheets/AO3400.pdf
but that these are smd parts, 2n7000 are the 'old' through hole parts.

or perhaps, another simplier way is to 'throw away' the 2n7000 and just use 2n2222 lol

 

or perhaps, another simplier way is to 'throw away' the 2n7000 and just use 2n2222 lol

That would be my choice.

 

use mosfet but pick one that works with 3.3V such as AO3400A. just a tiny (and cheap) mosfet - no other parts. it will turn on with less than 2V and it will happily handle couple of Amps.

 

use mosfet but pick one that works with 3.3V such as AO3400A. just a tiny (and cheap) mosfet - no other parts. it will turn on with less than 2V and it will happily handle couple of Amps.

well this 'example' is just that 2n7000 is about one of the very few through hole parts that are widely available / distributed e.g. in the 'online flea markets' (aliexpress, ebay, amazon, etc).

it seemed many of the 3.3v logic level mosfets are after all smd parts, mostly sot23 etc.
e.g. bss138
https://www.onsemi.com/download/data-sheet/pdf/bss138-d.pdf
ao3400 (and various ao34xx) are the other lot

 

BSS138 is not logic level, it needs 4.5V tor turn on and most GPIO are only 3.3V. AO3400A turns on with 2V.
Also AO is more powerful, it can handle several Amps of current - continuously (Rdson is 100x lower than that of BSS138).

and you can order your own PCBs with some or all parts populated. could also include an LED. it fits easily in breadboard. could have fewer pins so it takes less space. and if you plan to have more than one output, use driver array like ULN2xxxx

btw the board is so tiny that does not meet smallest size requirements for PCBA so it would need to be panelized (easily done) and then you get 50 or so for something like ten bucks.



or...

just order ready made breakout boards from ali as well as transistors and solder them yourself
https://www.aliexpress.com/item/1005006626188055.html?spm=a2g0o.productlist.main.19.701c78cddtO4xz&algo_pvid=fe2e4bae-7314-42d8-b241-141082f95f1a&algo_exp_id=fe2e4bae-7314-42d8-b241-141082f95f1a-18&pdp_ext_f={"order":"291","eval":"1"}&pdp_npi=6@dis!CAD!2.56!1.40!!!1.81!0.99!@2101c67a17570117218731364e919a!12000037858523309!sea!CA!0!ABX!1!0!n_tag:-29910;d:d3f7156c;m03_new_user:-29895;pisId:5000000174129003&curPageLogUid=nNk61qTqCQRe&utparam-url=scene:search|query_from:|x_object_id:1005006626188055|_p_origin_prod:

 

@panic mode thanks
yup, bss138 doesn't have as good specs as ao3400 (or ao34xx)
but interestingly this datasheet says VGS(th) 1.3v typ 1.5 max
Rds(on) vgs 4.5v ~ 1 ohm typ, 6 ohm max
https://www.onsemi.com/download/data-sheet/pdf/bss138-d.pdf
of course this is still way above that of ao3400
https://www.aosmd.com/sites/default/files/res/datasheets/AO3400.pdf
Rds(on) vgs 4.5v ~ 19 milli ohm typ, 33 milli ohm max
Rds(on) vgs 2.5v ~ 24 milli ohm typ, 52 milli ohm max

there are actually quite a spread of 'sot23 pcb adapters'
https://www.aliexpress.com/w/wholesale-sot23-adapter-100-pcs.html
some of which are sold as tsop10 adapter boards with a reverse side with sot23 spaced footprints at 0.95mm

 

yes, you can buy adapters, mosfets and headers there. just a bit of soldering and life is good.