Original, WORKING CONDTION WW2 German Luftwaffe Drehzahlgeber Tach Generator Fl.20230. This Drehzahlgeber (Tachometer Generator), Fl.20230-1, produced for use with German the Jumo 004 & BMW 003 Turbo Jet and HWK Rocket Engines…as well as the late-war Me109 and Fw190D9. This instrument attached directly to the Engine, and sent a signal to the Drehzahlmesser (Tachometer) on the main control panel, indicating to the pilot the current engine speed. Though the tachometer used on the early Me262 (Jumo 004 engines) had an indicator that displayed 0 – 12000 rpm (14000 rpm on later models), it was really only accurate from to 9000 rpm. As such, at lower speeds, with the help of a a push button switch that was installed on the side console, the pilot was able to take a reading from the Doppeldruckanseiger (Fl.20233) that gave him a low-speed reading from the Riedelanlassmotor or the engine itself.