Minifon p55 wire recorder collection. Ebay auction

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I'm selling my world class Minifon collection. The original spy recorder.

It includes 8 minifon recorders.( 1 p-55 kit, 2 attache, 1 p55 L, 3 p55 S, and 1 Protana ITT Special. 3 microphone wristwatches, 5 speakers , original boxes, 3 ac power supply, 1 automobile connecting cord, carry cases, 1 telephone adapter, manuals, 2 original batteries, plus recording wire.

I'm not sure what does and does not work.


Below is some info from websites.


Minifon P55 (1951)

Somewhat out of the time sequence, but will be listed here to keep all wire recorders grouped together...

The Minifon was released in 1951. It's main attribute was it's small portable size and claimed to fit in one's shirt pocket (assuming I suppose. one has a Gi-normous shirt pocket !.... ) Nevertheless, compared to the Websters and Silvertone home machines etc, it was indeed truly portable. The P55 (the most popular) measured approx 7x4x1.6". It was powered by 3 batteries: a single 1.5 v filament battery (AA size), a single 30 V anode battery (plate voltage supply) and a single 12V battery for the reel/capstan motor drive. An optional AC adapter was available that only supplied 9-12v for the motor drive, which was the battery with the shortest life and also (naturally) the most expensive.

The filament battery had a life expectancy of 20 to 30 hrs, the anode battery: 150 to 200 hrs, and the motor battery: 10 to 12 hrs.

The included microphone served as both a microphone as well as a speaker - - though an optional telephone pickup, headphone, as well as a dedicated "full" sized speaker was available at additional cost. The P55 initially sold for $289 here in the US back in the early 1950's (quite a hefty sum back then), but it was truly portable and considered state of the art "microminiaturization" for it's day. The P55 employed vacuum tube technology with 3 "micro" (and considered highly power efficient) vacuum tubes. Since it was battery powered, a rectifier tube and thus power supply was not required, as all operating voltages were supplied from the 3 on board batteries (that alone saved a lot of weight and significantly reduced the number of required components) Not surprisingly, it was quickly adopted by many governments as being the ultimate "spy" recorder of it's day. Minifon even designed a wristwatch microphone, that looked like a watch, but was actually a microphone ! Today, that wristwatch microphone is somewhat of a collector's item.

Fidelity was on par with the full size Websters, despite the wire size being nearly half the thickness of the much larger Webster reels (which was already hair thin). Due to the extremely thin wire used, wire breaks are far more of a problem. Minifon also opted for non-standard spool sizes and recording speed, insuring that only their equipment could be used for playback. Standard Webster style reels recorded at an industry agreed on 24 ips, while Minifon used a proprietary 30 cm/sec or about 11.8 ips.

Minifon Mi51 & P55 Miniature Wire Recorders

General Notes
The Minifon Mi51 wire recorder was introduced by Protona of West Germany in 1951 for covert surveillance use by government and other agencies. It used wire spools allowing 1 to 4 hours recording and cost around $US300. The case is cream coloured bakelite and the switches are push-pull types to allow easy use under clothing. The record/playback function is controlled by the type of plug used - a short plug is used for the microphone whilst the longer phone plug operates the changeover switch for playback. The wire spools for this model have a black and white centre which can be seen through a small window in the top, which enables the operator to know when the unit is running. The unit is very small (170 x 110 x 35mm), about the size of a video cassette. Three batteries were needed, a 9V heavy duty one for the motor and 1.5 and 30V A & B batteries for the 3 miniature valves used which consisted of 2 x DF67 and 1 x DL67 Philips types. A range of accessories was available which included a wrist watch microphone and body harness.

The reason for the large take-up spool on this model is to cater for wire lengths giving up to 4 hours recording time. The wire speed of around 24 cm/sec is controlled by the take-up spool, and to keep this fairly constant over the 3.5 kms of wire, the spool needs a large inside diameter. The need for careful winding of the human hair sized wire means that the recording head must be made to rise and fall to provide smooth layering on the take-up spool and during re-wind; hence the circular protrusion on the top cover.

The Mi51 inspired the Australian, Dr David Warren, to devise the first "Black Box" flight data recorder in the 1950s. By the time the prototype was built in 1956, seen right, the later P55 components may have been used as can be seen from the wire spools and recording head. Although tape recorders were available at this time, the magnetic tape would not be able to give as much recording time or to survive the amount of heat or G forces that could occur in a crash.

The Mi51 covert unit is often confused with the next model, the P55, introduced by Protona in 1955. The P55 came with a wider variety of accessories and had control buttons that were more convenient to use as it was not normally hidden under clothing. It had both spools the same size and would still allow up to 4 hours recording, depending on model. The P55 was later replaced by a transistorised magnetic tape version, the Attache model, once this technology was sufficiently advanced, though recording time was limited to 1 hour, much less than the wire based models. Protona was taken over by Telefunken about 1962 who continued with the Minifon brand until 1967.

An excellent book in German on the Minifon series of recorders has been written by Roland Schellin and is titled "Der Spion in der Tasche" (The Spy in the Pocket).

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heres some pics