Editing Transistor (section)

==Comparison with vacuum tubes==
Before transistors were developed, [[vacuum tube|vacuum (electron) tubes]] (or in the UK ''thermionic valves'' or just ''valves'') were the main active components in electronic equipment.

===Advantages===
The key advantages that have allowed transistors to replace vacuum tubes in most applications are
* No cathode heater (which produces the characteristic orange glow of tubes), reducing power consumption, eliminating delay as tube heaters warm up, and immune from [[cathode poisoning]] and depletion.
* Very small size and weight, reducing equipment size.
* Large numbers of extremely small transistors can be manufactured as a single [[integrated circuit]].
* Low operating voltages compatible with batteries of only a few cells.
* Circuits with greater energy efficiency are usually possible. For low-power applications (for example, voltage amplification) in particular, energy consumption can be very much less than for tubes.
* Complementary devices available, providing design flexibility including complementary-symmetry circuits, not possible with vacuum tubes.
* Very low sensitivity to mechanical shock and vibration, providing physical ruggedness and virtually eliminating shock-induced spurious signals (for example, [[microphonics]] in audio applications).
* Not susceptible to breakage of a glass envelope, leakage, outgassing, and other physical damage.

===Limitations===
Transistors may have the following limitations:

* They lack the higher [[electron mobility]] afforded by the vacuum of vacuum tubes, which is desirable for high-power, high-frequency operation{{snd}} such as that used in some over-the-air [[television transmitter]]s and in [[travelling-wave tube]]s used as amplifiers in some satellites
* Transistors and other solid-state devices are susceptible to damage from very brief electrical and thermal events, including [[electrostatic discharge]] in handling. Vacuum tubes are electrically much more rugged.
* They are sensitive to radiation and [[cosmic ray]]s (special [[radiation hardening|radiation-hardened]] chips are used for spacecraft devices).
* In audio applications, transistors lack the lower-harmonic distortion{{snd}} the so-called [[tube sound]]{{snd}} which is characteristic of vacuum tubes, and is preferred by some.<ref name=Veen1>{{Cite conference
 |last        = van der Veen
 |first       = M.
 |title       = Universal system and output transformer for valve amplifiers
 |book-title   = 118th AES Convention, Barcelona, Spain
 |year        = 2005
 |url         = http://www.mennovanderveen.nl/nl/download/download_3.pdf
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20091229114846/http://www.mennovanderveen.nl/nl/download/download_3.pdf
 |archive-date = December 29, 2009
|df          = mdy-all
}}</ref>