The Western Electric 60 AP Selector is a sort of all-mechanical intelligent relay, one which will only open when it receives a particular coded sequence of pulses. Used as the heart of many railroad and industrial phone switching systems in the early part of the 20th century, the core of the device is a rotating circular wheel with 17 holes around its edge. The wheel rotates a fixed number of degrees every time a pulse passes through the coil armature and is restrained by springs such that when power is removed from the coils, the wheel will snap back to its original position. A restraining arm lines up with the wheel along the holes in it's edge; pins placed in these holes that line up with the restraining arm when power is removed will hold the wheel in place, preventing the springs from snapping it back to home position. By placing pins into the various positions along the wheel a series of numbers can be encoded into the device, a matching set of pulses will cause the wheel to rotate through its full range and close a pair of contacts.

It should be noted that a limitation of this device is that it can only be encoded with a series of numbers that totals up to 17, the number of pulses needed to rotate the wheel to its final position.

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The Sanyo Micro Pack 35 is a compact audio recording machine which uses small magnetic tape reels fitted in a removable cartridge format. Originally released in 1964, Sanyo licensed the technology to other manufacturers, as well as providing the internal mechanism for the tape transport to third parties. In the United States, Sanyo units were re-branded by Channel Master and sold under the "Lodestar" trademark, the example shown here is one such unit. The most notable feature of the Micro Pack 35, other than its size, is it's tape cartridge system. Recordings are stored in removable modules which contain two magnetic tape reels stacked vertically, similar to the arrangement used in many flight recorders. Each tape can hold approximately 25 minutes of audio per side, a foil tag is located at each end of the tape, which is read by a conductivity sensor to trigger the recorder's auto-stop feature. The build quality of the Micro Pack 35 recorder is extremely high, Sanyo marketed the device as a 'sound camera' and manufactured the recorder to look and feel like a high end camera of the era. As with most cameras, all of the Micro Pack 35's controls are located on the top of the device, with knobs for speed and transport control, as well as a moving needle level gauge.

Unfortunately, while compact, the Micro Pack 35 delivers relatively poor sound quality for the era. The lack of a capstan and pinch roller, along with a clumsy friction drive system, result in far too much pitch and speed variation for music recording. Micro Pack 35 recorders are mainly useful for voice recording; the example shown here was used in a county morgue, and was found with several tapes of cancer patient autopsies. Other manufacturers leaned heavily into the use of voice recording to replace written letters; the Westinghouse version of this recorder even came prepackaged with cardboard mailers sized to hold a single Micro Pack 35 cartridge.

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Cockpit voice recorders like this B&D Instruments unit are used to provide investigators with clues into the last moments of a aircraft crash. These devices are mounted in nearly every aircraft and continuously record sounds inside the cockpit on an infinite loop. Though commonly called a 'black box' in popular media, most flight recorders are painted orange or yellow for easy visibility in a chaotic crash site. The heart of this device is a International Tapetronics four track tape recorder, which stores analog voice recordings on a single reel of magnetic tape. The tape is wound in an endless loop similar in function to an 8 track music cassette; fresh tape is pulled from the center of the reel, recorded on, and wound back onto the outside in an endless cycle. Much of this flight recorder's internal volume is taken up by the protective barriers that allow the Tapetronics module to survive a violent crash. A layer of magnetic shielding within a thick ceramic encasement provides protection from shocks, flames, and magnetic fields. This is further sealed inside of a heavy machined aluminum block, with a gasketed seam to protect against water landings. The small amount of electronics needed to control the Tapetronics module are located in a card cage in the rear quarter of the flight recorder's case.

The empty bracket on the front of the device would have originally contained a Dukane DK100 emergency transmitter. This battery powered device would broadcast a tracking signal in the event of a water crash, guiding investigators to the location of the voice recorder. The emergency transmitter will activate automatically when immersed in water.

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Back in the time before iPhones, or any phone, messages were sent over long distances using Morse code and telegraph sounders, which tap out a "binary" stream of data that is sent electrically over a wire. This telegraph sounder, made by the J.H. Bunnel company (not to be confused with the distressingly similarly-named Bunnell Telegraph company), is a fairly typical example of such a device. A pair of 50 ohm coils moves the main lever, which is mounted in a 'U'-shaped frame. Three thumbscrews with locking nuts adjust the travel of the main lever and the tension of the lever spring. Note that the diode bridging the two contacts in the photo is not part of the original device; but is a modern addition designed to protect solid state signal sources from damage by inductive kickback from the coils.

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The Gardinier papertape keyer is designed to read Morse code off of a series of holes punched in a roll of double-sided paper tape, and transmit the data down a pair of wires. Since this device uses papertape that is almost identical to that of the Instructograph (pictured below), it was probably intended to be used as a Morse code practice device instead of for transmitting Morse code messages to far-off places.

The papertape is fed by an electric motor, and a small knurled knob on the front of the machine can be turned to control the speed. There is also a small plastic lever in the contact gap at the top of the machine that can be used to adjust the gap's width. At this time, this unit has not yet been restored and has never been powered up.

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The Instructograph is designed for teaching Morse code, and includes coursework in the form of double-sided punched papertape reels. The reels are fed through a set of contacts, which are connected to binding posts where the user can connect a code oscillator or similar device. The motive power to pull the reels through the contacts is provided by a clockwork mechanism. There is a large crank on the side of the device to wind the machine, as well as a speed control lever on the top, which allows the user to select a narrow range of speeds for the device. The speed control is hooked up to a governor, similar to the kind used in rotary phone dials. The contact gap at the point where the papertape is read is adjustable by means of a small thumbscrew.

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While we normally don't cover consumer technology, sometimes we encounter something so bizarre or unusual that it practically demands documentation. This handheld cassette recorder, produced by EROs in the late 1970s, would be mundane if not for it's singularly hideous external appearance. This tape player is encrusted with fake gold and decorative fragments on almost every surface, so much so that it would not look out of place on the set of a James Bond flick. Even the buttons are covered in a fake gold coating. The features of this tape recorder are otherwise fairly mundane, though it does include a mechanical tape counter as well as a small analog meter to display battery level. A removable foot pedal allows the tape to be stopped and started hands-free, to aid in transcribing dictation.

This tape recorder also comes with an unusual attachment; a ring-shaped pickup which is designed to be attached around the earpiece of a Western Electric rotary telephone. With the pickup in place, both sides of a phone conversation can be recorded. Even Goldfinger needs to maintain records of his business transactions.

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The BC-603 is a World War 2 era American radio receiver best known for its use as the primary radio receiver in the M4 Sherman tank. A typical Sherman of the era would have been equipped with one or two BC-603 receivers as well as a BC-604 transmitter, all of which would have been mounted in the tank's turret. Almost half of the BC-603's internal volume is taken up by a large programmable tuner that controls the receive frequency of the device. This tuner, which consists of a complex stack of gears and toothed levers, allows up to 10 frequencies to be programmed into the radio for quick selection. A programmed frequency can be selected from the grid of chrome-plated buttons on the left side of the device. The BC-603 can also be tuned manually using the small wheel located below the program selection buttons. The BC-603 would have originally been powered by a 12 or 24 volt motor-generator pair, but the example shown here has been converted to 120 volt operation. The dynamotor, which would have been mounted in a compartment on the rear of the radio, has been removed as part of the conversion process. Though the BC-603 was typically used with headphones, the radio also has a front-mounted speaker, which is covered by a rotating grille that can be closed to reduce the speaker's volume.

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Many aircraft cockpit voice recorders had removable magazines such as this one for the storage of voice data. This recording magazine contains a spool of magnetic Mylar tape for the storage of voice data, much like the magnetic tape used in a consumer-grade cassette tape player. Unlike a conventional cassette player, the recording heads for this device are mounted within the magazine itself instead of the recorder, which prevents the tape from being exposed to dust and debris during installation and removal. The magazine contains two heads to double the capacity of the tape: one is used when the tape is running clockwise, and the other is used when the tape is running counterclockwise. The two reels of the tape are stacked one on top of the other to reduce space, a system of gears and springs controls the tension between the two reels as the direction of rotation changes. A small window on the top of the magazine allows the level of tape remaining to be seen without removing the cover.

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