While the junction gate field-effect type has one p-n junction between the conducting channel and gate, the bipolar junction type has two in series. The first functional point-contact one was constructed at Bell Labs, replacing vacuum tubes found in older electronic equipment. They are currently used as electronic amplifiers and switches and constructed out of semiconductor materials. Although discrete ones are still produced, they are much more 
While the junction gate field-effect type has one p-n junction between the conducting channel and gate, the bipolar junction type has two in series. The first functional point-contact one was constructed at Bell Labs, replacing vacuum tubes found in older electronic equipment. They are currently used as electronic amplifiers and switches and constructed out of semiconductor materials. Although discrete ones are still produced, they are much more common in another application. FTP, name this semiconductor device whose counts on integrated circuits double approximately every two years as per Moore's law.
While the junction gate field-effect type has one p-n junction between the conducting channel and gate, the bipolar junction type has two in series.
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