Neither one nor Many

December 28 2017

Some electronics notes


L7805CV - 5V - Voltage regulator

  • Pins from left to right: {input, ground, output}
  • The top part is also ground.
  • Can attach heat sink if needed
  • Quiescent current is not so nice: 6 mA
  • "Not really suitable for usage in batteries, consider instead: Low drop out regulator"
  • Info on the part:

Ultra-Low Quiescent Current LDO Regulator

IRFZ44N Mosfet

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

  • Pins from left to right: {gate, drain, source}
  • Enabling "gate" will enable electricity to flow from source to drain.

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.

  • Pins from left to right: { VCC DATA NC GND } (NC = No connection )
  • Info on the part:

  • ESP8266, wemos d1 arduino studio + DHT22:

  • 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: also:

  • Also found you should use a 10k resistor as a pull-up here:

3.3V voltage regulators


PIR 5Pcs/Lot SR501 HC-SR501 Adjust IR Pyroelectric Infrared PIR module Motion Sensor Detector Module for Arduino


upload issues

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Ray Burgemeestre
february 23th, 1984

C++, Linux, Webdev

Other interests:
Music, Art, Zen