Someone brought this kit to my attention a couple of weeks ago, so I ordered one (as it's was crazily cheap - £7.45 )
https://www.banggood.com/DIY-Meter-...ntent=vera&emst=2NKh40Be80_237878_1013964_129
It came this morning, so I've put it together and it works great - it uses an ATMega, and not a great deal else really - the test transistor in the picture is a BC107. All the details are in the web link above, scroll down to the reviews for a link to the instructions and circuit.
https://www.banggood.com/DIY-Meter-...ntent=vera&emst=2NKh40Be80_237878_1013964_129
It came this morning, so I've put it together and it works great - it uses an ATMega, and not a great deal else really - the test transistor in the picture is a BC107. All the details are in the web link above, scroll down to the reviews for a link to the instructions and circuit.