I recently obtained an original pamphlet with 'Instruction Data for ERLA DUO-REFLEX CIRCUITS, using the Selectoformer type coils, Erla Bulletin# 21, dated March, 1924.

I have scanned the booklet and the 12 pages are available on My Coils page.  Pictorials include the Erla Three-tubeDuo-Reflex, Erla two-tube Duo-Reflex, and the Erla single-tube Duo-Reflex circuits.  I am trying to restore the single tube circuit that I bought off of eBay.  Hope this helps anyone out there.

John, WØHII