What were the earliest diodes used?
        
        
     
    
 replied to:  jondabomb
         
        
            
            Replied to:  What were the earliest diodes used?
         
        The principles of diodes was developed as early as 1873 when Frederick Guthrie worked out how a thermionic diode should work 
        
        
     
    
 replied to:  Thraxel
         
        
            
            Replied to:  The principles of diodes was developed as early as 1873 when...
         
        The first crystal rectifier was developed and patented by 1899