Editing Telegraph key (section)

====Semi-automatic key====
[[Image:Bug telegraph key made by Weston Hadden, c. 1913 - Bennington Museum - Bennington, VT - DSC08642.JPG|thumb|Early "bug" telegraph key invented in 1913 by Weston Hadden]]
A popular side-to-side key is the semi-automatic key or "bug", sometimes known as a [[Vibroplex]] key after an early manufacturer of mechanical, semi-automatic keys. The original bugs were fully mechanical, based on a kind of simple clockwork mechanism, and required no electronic keyer. A skilled operator can achieve sending speeds in excess of 40&nbsp;words per minute with a bug.

The benefit of the clockwork mechanism is that it reduces the motion required from the telegrapher's hand, which provides greater speed of sending, and it produces uniformly timed ''dits'' (dots, or short pulses) and maintains constant rhythm; consistent timing and rhythm are crucial for decoding the signal on the other end of the telegraph line.

The single paddle is held between the knuckle and the thumb of the right hand. When the paddle is pressed to the right (with the thumb), it kicks a horizontal [[pendulum]] which then rocks against the contact point, sending a series of short pulses (''dits'' or dots) at a speed which is controlled by the pendulum’s length. When the paddle is pressed toward the left (with the knuckle) it makes a continuous contact suitable for sending ''dahs'' (dashes); the telegrapher remains responsible for timing the ''dahs'' to proportionally match the ''dits''. The clockwork pendulum needs the extra kick that the stronger thumb press provides, which established the standard left-right paddle directions for the ''dit''-''dah'' assignments that persists on the paddles on 21st&nbsp;century electronic keys. A few semi-automatic keys were made with mirror-image mechanisms for left-handed telegraphers.