Am. u. Hum. Clock C/2, 7,5 L/36 Sch. T. 5a, Carl Zeiss, Kriegsmarine, circa 1938

Am. u. Hum. Uhr C/2 (Emigration gauge and height difference measurement clock) it is a “Flak-Range” watch made by Carl Zeiss for the Kriegsmarine in around 1938.

This tool allows you to provide a real-time estimate, calculated through a Gamma random variable (also called Erlanghian random variable), of the real inclination radius of an aerial target. The instrument was provided with appropriate information such as target heading, range and altitude changes.

This data was taken by a Flak control unit and manually set on the instrument. By subsequently activating the emigration stroke mechanism, the instrument provided the measurement of how much the plane was moving laterally (real inclination radius) and consequently, by activating the Zeitzünder machine (Fu-Ze), the expected range to detonate was set the cone in good time, while the control unit provided the bearing and the necessary ballistic elevations of the gun for the alignment of the shot.

Inside this instrument there is a drum with a diagram set for the calculation of a 7.5 cm FlakL/36 unit.

When the clock is activated, it provides measurement time via a periodically interrupted electric current that operates the buzzer magnet.

The buzzer beeps are emitted at regular intervals and passed through two cables simultaneously to two transfer meters and heard by operators via headphones.

The periodically interrupted current, passing through the two cables, activates two buzzers whose signal, through an electric impulse, is transmitted first to one and then to the other cable so that the buzzers work alternately and there is no interruption in data transmission to the Zeitzünder machine (Fu-Ze), i.e. the instrument necessary to set the explosion time of the projectile according to the altitude of the aircraft.

Furthermore, there are probable possibilities that this instrument could have been used by Flak (for the calculations described above), even with artillery equipped with a greater or lesser caliber since the rotating drum equipped with a numerical scale designed for the calculation of the aerial detection, can easily be replaced.

The instrument is fully functional and its weight is approximately 22 kg.

Note: certainly given the extreme effectiveness of the instrument in carrying out calculations for shooting against aircraft, it was deemed appropriate to reuse it, repainting it in DAK colour, on the Northern Afrika front. This can be seen from the fact that the original Kriegsmarine gray color is still present on the back of the instrument.

WRITING IN RED:
1- Wennsummer versagt, prufen ob sicherung durchgebrannt oder summer kontakte kleben! = If the buzzer does not work, check the fuses or buzzer contacts.

WRITING IN WHITE COLOR:
2- Zufuhrungsschleifring = Power contact
3- AM Schaltscheibe = On the switching disk
4- Hum-Scaltscheibe = Switching disc hum
5- Sicherung = Fusible (1 Amp.)
6- Verdunkel = Darkening
7- Widerst. = Resistence
8- Summer = Buzzer
9- Hum I od. Telefon I/II = Telephone Buzzing (headphones) I/II

TOP INSTRUMENT INDICATORS (from left to right):
1- Laufzeit in minuten = Running time in minutes
2- Dunkel = Dark
3- Hell = Light
4- Aus. = Off
5- Hum = Buzzing (buzzer)
6- Am 1/3 = Alternating pulses of current at the buzzer every second (?)
7- Am 1/6 (rosso) = Alternating pulses of current at the buzzer every second (?)
8- Regulierung = Speed regulation of alternating current pulses per second, or mechanical regulation of advance or delay. The letter “V” means Before (Vorwärts), while the letter “N” (Nach) means After.

SIDE CONNECTORS:

9- Single voltage input of 12 Volt

10- 2 Inputs for headphone listening (buzzer buzzing).

ZEISS ARCHIV:
The Am and Hum clock C/2 is used for anti-aircraft shooting to determine the measuring time when the target height and target distance are continuously adjusted by hand. When switched as an am clock, it gives the measurement time as short buzzers at regular intervals. The buzzer signals are routed through 2 cables simultaneously to 2 emigration meters and listened to there with headphones. Connected as a Hum clock, it gives the measuring time through a periodically interrupted electrical current that activates a magnet on the Hum. The periodically interrupted current is carried through 2 cables to 2 Hum, and the current surge is transmitted alternately through one and then through the other cable, so that both Hum work alternately and there is no break in the emigration measurement.