🧵 Sensors
Anonymous at Thu, 4 Jul 2024 00:15:52 UTC No. 16266909
How do they work, really?
>Oh, the sensor detects x and sends a signal to a circuit
Okay, but how? What does that mean in some detail? How does a sensor detect heat, for instance, or detect the edge of an item?
Anonymous at Thu, 4 Jul 2024 00:17:27 UTC No. 16266911
>>16266909
Anon... are you alright?
You realize that electric signals travel through real physical space and interact with physical phenomena... right?
Anonymous at Thu, 4 Jul 2024 00:19:54 UTC No. 16266915
>>16266911
Yes, but I don't understand how the sensor sends electricity when a certain condition is met.
Anonymous at Thu, 4 Jul 2024 00:21:02 UTC No. 16266916
>>16266915
through a circuit board. silicon wafers which channel the electric signals into microscopic on/off switches which power logic which indicates the state.
Anonymous at Thu, 4 Jul 2024 00:33:58 UTC No. 16266933
>>16266909
Sensors such as temperature sensors are variable resistance sensors.
You apply power to them and measure the voltage output.
Anonymous at Thu, 4 Jul 2024 00:39:02 UTC No. 16266942
>>16266909
Care to give us some context about exactly what it is you're trying to resolve here?
Anonymous at Thu, 4 Jul 2024 00:46:54 UTC No. 16266952
>>16266915
the answer you're looking for is diodes. things that block the flow of electricity only under some conditions. there exist materials that respond to basically anything by changing their structure. these materials are used to build metaphorical switches within circuits that have a power supply. some diodes allow the power to flow when they're hot enough, cold enough, dark enough, bright enough, compressed enough, free enough, etc. and you can stack many of them together and use filters to create more advanced or precise detectors.
Anonymous at Thu, 4 Jul 2024 00:47:54 UTC No. 16266954
>>16266952
>>16266933
otherwise it's this if you're thinking less digital
Anonymous at Thu, 4 Jul 2024 01:01:33 UTC No. 16266965
>>16266909
a sensor's electrical properties are sensitive to the thing it's designed to measure
for electronics, this invariably means it changes it's resistance, or modulates a current or voltage in a way that depends on the thing being sensed.
>heat sensor
resistance increases for most materials as a function of heat
calibrate this variable resistance against known temperatures, then measure the resistance of the element with a wheatstone bridge. viola, a thermometer.
it's like this for everything
Anonymous at Thu, 4 Jul 2024 04:17:28 UTC No. 16267192
>>16266909
if you know anything about signal processing then sensors are just electromagnetic gadgets that can interact with other electromagnetic gadgets like light and atoms. so the sensor "detects" fluctations in electromagnetic (and quantum fields) by changes in its own electromagnetic fields. these cascade down the apparatus until some signal goes from low value to a high value. that's it, it's really basic stuff
Anonymous at Thu, 4 Jul 2024 04:24:26 UTC No. 16267195
>>16266915
1) (insert mechanism here) generates electricity in response to a phenomenon you want to sense or measure (ex. light using the photoelectric effect, sound or vibrations using piezoelectrics, heat using thermocouples, etc.)
2) electricity feeds into a circuit designed to take the generated electric current and output either raw or filtered signal or conduct some rudimentary data decomposition
Anonymous at Thu, 4 Jul 2024 04:40:46 UTC No. 16267210
>>16266909
You design a sensor in some way that changes the way it interacts electrically when exposed to the conditions you're looking for.
Need to detect light? Thin films of cadmium sulfide experience a change in conductivity when exposed to light.
Need to detect fluid pressure? Have a piston with "normal' pressure air on one side and the pressure you're testing on the other. Then just see how far it moves.
Basically, you just have to get creative for the individual task at hand.
🗑️ Anonymous at Thu, 4 Jul 2024 04:45:53 UTC No. 16267215
>>16266909
>>16266915
in your picrel you have a laser on one side and a light sensor on the other
when the light sensor is active a switch is kept closed, when the laser is blocked the sensor becomes inactive and some circuit becomes active
something like that
pretty simple bro
Anonymous at Thu, 4 Jul 2024 04:52:12 UTC No. 16267222
>>16266909
A transducer converts energy from one form into another form. Most sensors convert some outside process into electrical signals. The most common sensor after a mechanical switch is going to be the proximity switch which is most often to ensure automated assemblies are in the right location.
Of these proximity switches, the inductive proximity switch is the most common and fairly cheap. A target is set on the mechanical assembly and the inductive sensor is set to detect that target when it is in the right position. The mechanism works by coupling of an inductive coil in the circuit with the ferrous target. There are a number of circuit designs, so the generic way to describe what happens is the circuit handles two states and will signal accordingly.
The website below goes into specifics that are probably outside your skill level.
https://theorycircuit.com/sensor/in
There are a number of ways to detect temperature: thermopiles, thermocouples, bimetallic elements, resistive elements, lasers, etc. Each have their own physical phenomenon accompanying them.
For example, thermocouple have dissimilar metals in contact at a point producing varying currents at different temperatures.
Edge detection is typically not edge detection, but merely a tuned photocell that is set to flag when an object is within a certain proximity to it. For example, a photoresistive element will change resistance depending on how much light is striking its surface. This change in resistance correlates with a change in voltage that determines circuit state. A variable resistor can be used to set the threshold for when the circuit is in the true state.
True edge detection is normally done by machine vision. This uses cameras and image comparison to determine what an edge looks like. It typically is counting pixels on a fully conditioned image taken from a tuned/calibrated camera under specific lighting conditions.
Anonymous at Thu, 4 Jul 2024 05:30:50 UTC No. 16267246
>>16266954
What? Diodes and Resistors are both analog electronic components.