ðiːz kənfˌɪɡjɚɹˈeɪʃənz wɜː kˈɛpt ʌntˈɪl sˌɛmɪkəndˈʌktɚ dʒɜːmˈeɪniəm dˈaɪoʊdz bɪkˌeɪm ɐvˈeɪləbəl, mˌeɪkɪŋ ðɪs tˈaɪp ʌv tˈuːb ˈɑːbsəlˌiːt.
These configurations were kept until semiconductor (germanium) diodes became available, making this type of tube obsolete.