This block uses a potentiometer or variable resistor as an angle sensor.  If you wanted, you could attach a large knob or disc to the potentiometer marked in degrees.  Or you could use it to measure the position of something else using a gear wheel or pulley.  The 1k resistor is just for protection in case the output gets shorted but is not really necessary.

This block uses a flat disc piezo device which generates a voltage when it is pressed or tapped.  It could be used as a coin sensor in a jukebox for example.  The voltage generated is only low so you will need a sensitive detector block such as a comparator.

Here a motor is used as an input device by making it a generator.  When the motor is spun it generates a voltage which can then be detected by a flowing block.  Again the voltage produced is only low so you will need a sensitive detector block.  The diode is there to protect the following block from too much reverse current, but that will only be a problem if the motor is spun at high speed.

This block uses a slot sensor device which is really an opto-coupler with an air gap.  It uses an infra-red LED on one side of the slot and an infra-red detector on the other.  Normally, the light crosses the gap so that the photo-transistor conducts causing a low output.  When something interrupts the light then the output goes high.  Note in the PCB layout you will need a slide switch block before this one to supply power to the infra-red LED.  Unfortunately, you won’t be able to check this block using Crocodile Technology.  The sensor is Rapid 58-0304.

For this block, the infra-red LED shines out and the photodiode detects the reflection.  Output is low if there is no reflection (object not present).  If there is an object in view then the output will be high providing it reflects enough light.  Note that the range of the particular sensor used is only about 3mm.  If you want a greater range you will need to add some amplification or build your own detector circuit.  The sensor is Rapid 58-0914.  A switch has been added to allow you to switch the LED on or off by the preceding block if you wish.

This block also appears on the Sound page along with a sensor that uses a loudspeaker.  This one uses an electret microphone which includes a built-in amplifier.  This needs a power supply, provided by the 10k resistor.  The 1k resistor and 100uF capacitor are there to make sure the power supply is clean, otherwise you might get feedback resulting in a howling sound.  The output of the microphone is ac coupled using another capacitor.  1uF should give reasonable bass response; you could use a smaller capacitor, say 100nF.