distortion in transformer cores, N. Partridge, 1939

This is the first of a series of articles in which the question of amplitude distortion arising in the iron core of a transformer will be dealt with on a quantitative basis. Information on this subject is scarce and the design data given is the outcome of original research by the author.

Be aware that tis articles appeared in the The Wireless World magazine from around 1939 (!). I’ve found some decent scans here: 1, 2, 3, 4.


the evolution of the input transformer, 1926

“Bell Laboratories – The Evolution Of The Input Transformer By F.E. Field” – see whole series of scans at isithifi.blogspot.com.

the Dynacord VRS-23 analog delay

(click images to enlarge)

The VRS-23 was a quite successful BBD delay in the 80’s and some thousands of units were sold during that time. It’s a mono-in / stereo-out device and capable of delay times up to around 400ms. Providing also very short timings and a modulation option makes it capable of creating chorus and flanger type of effects as well. There were different revisions available and shown here is a later one with the white faceplate. [Read more…]

the Ibanez AD202 analog delay

The so-called bucked-brigade device (BBD) delay line generator is a somehow quirky and really unique technical design. Such  devices are built upon analog components entirely, but being discrete in time they are halfway digital. Their analog input voltage samples are stored and moved through a line of capacitors one step after another and hence the name comes from analogy with the term bucket brigade: a line of people passing buckets full of water. [Read more…]