Part Number: 12AT7
Function: Triode Vacuum Tube, Receiving Valve
Package: 9 Pin Type
A triode vacuum tube is a type of electron tube, also known as a thermionic valve or vacuum tube, that contains three basic elements: a cathode, a control grid, and an anode.
12AT7 (also known in Europe by the Mullard–Philips tube designation of ECC81) is a miniature 9-pin medium-gain (60) dual-triode vacuum tube popular in guitar amplifiers. It belongs to a large family of dual triode vacuum tubes which share the same pinout (EIA 9A), including in particular the very commonly used low-mu 12AU7 and high-mu 12AX7.
The 12AT7 has somewhat lower voltage gain than the 12AX7, but higher transconductance and plate current, which makes it suitable for high frequency applications.
This is a specific type of vacuum tube, also known as a thermionic valve or electron tube. It is a double triode tube, meaning it contains two independent triode sections in a single glass envelope. This tube belongs to the 9-pin miniature (Noval) tube family.
The operation of a triode vacuum tube is based on the principle of thermionic emission. When a voltage is applied to the cathode, it heats up and emits electrons into the surrounding vacuum. The control grid, placed between the cathode and the anode, acts as an electrode that can modulate the flow of electrons from the cathode to the anode.