Neither one nor Many
Software engineering blog about my projects, geometry, visualization and music.
Some electronics notes
L7805CV - 5V - Voltage regulator
Ultra-Low Quiescent Current LDO Regulator
Not a "logic-level" mosfet, so I bought the wrong thing,
"If you want to drive this from an Arduino, which only outputs 5V, you will need a "logic-level" MOSFET. For this type of MOSFET, Vgs=5V is enough to turn it on. For example, the ST STP55NF06L would be appropriate and is comparable to the IRFZ44N, except the STP55NF06L is logic-level.
You should also have a resistor in series with the Arduino output to limit the current, since the MOSFET gate is highly capacitive and can draw a big instantaneous current when you try to turn it on (or off). 220 ohms or so is appropriate."
Logic-level alternatives: * FQP30N06L * STP55NF06
Difference between N or P-channel mosfet:
MOSFETs come in two polarities, P channel and N channel, where "P" stands for positive and "N" stands for negative.
P Channel To turn a P channel MOSFET on, you apply a negative voltage to the gate. This voltage is negative relative to ground. In a circuit, you connect the P channel MOSFET's source terminal to a positive voltage supply and the drain to a resistor connected to ground; the resistor limits the current flowing through the transistor. The circuit diagram symbol for a P channel MOSFET has an arrow pointing away from the gate.
N Channel An N channel MOSFET turns on when you apply a positive voltage at its gate terminal. The voltage is greater than the positive voltage supply at the drain terminal. A resistor between the positive supply and the drain limits current; for an N channel MOSFET, the source terminal connects to ground. The circuit symbol for an N channel MOSFET has an arrow pointing toward the device's gate.
DHT22 - Temperature and Humidity sensor.
Info on the part: https://create.arduino.cc/projecthub/attari/temperature-monitoring-with-dht22-arduino-15b013
ESP8266, wemos d1 arduino studio + DHT22: https://www.losant.com/blog/getting-started-with-the-esp8266-and-dht22-sensor
NOTE!!!! However, be careful hooking it up to 5V and then to an input pin on the ESP8266!!! I think I may have bricked one because of that. It seems to work for a while, but after some time I couldn't program the thing anymore. NOTE: It's unclear if it supports 5V imo: https://hackaday.com/2016/07/28/ask-hackaday-is-the-esp8266-5v-tolerant/ also: https://forum.arduino.cc/index.php?topic=428521.0
Also found you should use a 10k resistor as a pull-up here: https://odd-one-out.serek.eu/projects/esp8266-nodemcu-dht22-custom-modules-firmware/
3.3V voltage regulators
PIR 5Pcs/Lot SR501 HC-SR501 Adjust IR Pyroelectric Infrared PIR module Motion Sensor Detector Module for Arduino
https://forum.arduino.cc/index.php?topic=480507.0 https://github.com/esp8266/Arduino/blob/master/doc/faq/a01-espcomm_sync-failed.rst https://arduino.stackexchange.com/questions/41847/esp-wemos-d1-upload-fails