The diode bridge circuit was invented by Polish electrotechnician Karol Pollak [2] and patented on 14 Jan, 1896 under the number DRP[3] 96564. It was later published in Elektronische Zeitung, vol. 25 in 1897 with annotation that German physicist Leo Graetz also was researching this matter at that time.[4] Today the circuit is still often referred as Graetz circuit or Graetz bridge.[5]