Here it is :
View attachment 15952
R1 serves as a bypass resistor for the gate-source capacitance of the MOSFET and would by around 10kOhm when using a common N-MOSFET like the BS170 as long as the switching frequency wouldn't go up in the RF range which would require smaller values. R2 has to eat up the difference of the battery voltage and the LED's forward voltage (typically 2V) when the LED forward current (typically 20mA) flows. Here (14.4 - 2)V / 0.02A. Next standard value would be 680 Ohm.
Yes, as long as the Teensy is powered. With the Teensy off and the pin in hi-Z state, the Mosfet needs a defined state though, to protect the metal oxide gate isolation layer.Hello Theremingenieur.
1. Regarding the bypass resistor. would the teensy output being pulled low not acheive the same thing?
A series resistor as a current limiter or even an additional more powerful driver stage can be needed for power mosfets with higher gate capacitance. Here, since we are only switching one single 20mA LED, a small signal mosfet like a BS170 is sufficient. Its gate capacitance is small enough to not harm the Teensy's internal GPIO drivers which can source or sink 10mA.2. I don't think I've seen a series resistor going too the gate but I always wonder what limits the current on the teensy output to charge the gate capacitance?
If you aren't sure, using a driver or buffer is never wrong. But aren't you curious to fully understand the way of each single electron before you take the soldering iron in hands? I don't know how things are taught nowadays in schools and universities, but when I was young, people had to successfully finish their first year of theoretical semiconductor physics before they were allowed to experiment with CMOS stuff...I only have basic understanding of electronics and the couple of times I've required to used a mosfet basically as a switch I've used a driver because I wasn't sure.
This is a rather strange way to draw a schematic. While it may be technically correct, when using schematics to communicate with other humans, you really should follow the long established conventions.
Schematics are arranged so the more positive voltages are towards to top and most negative at the bottom.
Usually signal or data flow (or causal effects) are arranged left to right, where inputs are on the left side and outputs are on the right.