I have been trying to figure out a explanation to this question, can someone explain this ?
Why do most sensors have an electrical output, regardless of the physical nature of the variable being measured?
Electrical control systems have the following advantages over alternatives such as mechanical, pneumatic, hydraulic, etc.
- Speed. Electrical control systems are fast.
- Size. The control systems can be miniaturised.
- Power. Electricity is readily available. No compressors or pumps are required.
- Reliability. Electro-mechanical (relay) systems can have high reliability despite the moving parts. Solid-state (transistor, triac, etc.) can have far higher reliability as there are no moving parts.
- Distance. Electrical signals can be transmitted long distances without significant loss.
- Cost. Mechanical control systems require precision components which can be more expensive to manufacture and calibrate.
- Versatility. Electrical systems are very versatile. Transducers are available to convert light, sound, pressure, force, strain, radioactivity, viscosity, temperature, velocity, etc., into electrical signals.
The last one is probably the most important. While, for example, pneumatic logic and control systems exist and have their benefits (explosive atmospheres, for example) it is difficult to imagine how a light to air pressure transducer is going to beat a light-dependent resistor. In other applications such as temperature control mechanical solutions - car coolant thermostat, for example - are more than adequate.
That's easy- spirit of the time. Current technology is all about electronics. A hundred years ago it was different, Litmus for example hasn't electrical output :)
Sensors could press on or retract a pushrod.
With air-bearings, the wear factor would be excellent (long duration sensing).
But imaging the task of instrumenting a nuclear-test-site, with lots of crucial measurements having impulse-responses of nanoseconds or microseconds. The pushrod inertial serves as a low-pass-filter; the exploration of uranium at Los Alamos might still be underway, and USA might now be speaking German.