• Country
• United States of America (USA)

• Manufacturer / Brand
• Electrical Research Laboratories Inc. (Erla); Chicago, Illinois

• Year
• 1924

• Category
• Radio part (not a module) 

• Radiomuseum.org ID
• 208492

• Wave bands
• Broadcast (MW) and Long Wave.

• Power type and voltage
• No Power needed

• Loudspeaker
• - - No sound reproduction output.

• Material
• Various materials

• from Radiomuseum.org
• Model: Selectoformer Type A - Electrical Research

• Dimensions (WHD)
• 100 x 60 x 60 mm / 3.9 x 2.4 x 2.4 inch

• Notes
• Replacing variocoupler and wavetrap on any crystal or tube radio; increases volume and selectivity; as the name implies the Selectoformer operates simultaneous as a selector and transformer; frequency range 200 up to 700 meters band. (Simply an antenna input coil to be tuned by a standard 23-plate condenser, where the antenna is coupled by a separate winding. That is of course better than direct tuning of a lossy antenna).

• Net weight (2.2 lb = 1 kg)
• 0.6 kg / 1 lb 5.1 oz (1.322 lb)

• Literature/Schematics (1)
• Popular Mechanics (issue mar 1924)

• Author
• Model page created by Emilio Focosi. See "Data change" for further contributors.

• Other Models

• Here you find 134 models, 47 with images and 61 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
  All listed radios etc. from Electrical Research Laboratories Inc. (Erla); Chicago, Illinois