Until the early 70s, visible and infrared LEDs were very expensive - up to $200 for a piece, and therefore had little practical application.
Until the early 70s, visible and infrared LEDs were very expensive - up to $200 for a piece, and therefore had little practical application.
user
До початку 70-х рр. видимі й інфрачервоні світлодіоди були дуже дорогими й коштували до $ 200 за одиницю, у зв’язку з чим не мали широкого практичного застосування.
assistant