THOMA - Digital Frequency Meter TH2

The THOMA Frequency Meter TH 2 is designed  for on location shooting of film and video projects, as
 a means of testing the reliability of HMI lamps which depends on stable mains frequencies. The TH 2 is an essential accessory for working with a generator or shooting in countries where main frequencies fluctuate are uncertain. 

Nearly all HMI lamps shows us light-pulse with sinusoidal intensity corresponding to the alternating current supply frequency. If the line- or camera frequency do not correspond optimal than phase displacement will take place. In this case there is a different quantity of light for the exposure of the single picture available and the results are flickering pictures.

 With the TH 2 you can also check the speed of your camera. Thus the TH 2 is also an excellent measuring device for use in camera workshops.

The TH 2 has an optical sensor whitch gathers light-pulses. Mains frequency and camera speed can be measured between 10 to 100 fps. with a precision of 0.1 fps. The TH 2 built-in quarztime-base is 4.19 MHz, C-MOS technology is used throughout, the data display is a 3-digit LCD. Power consumption when operating is 5 mA at 9.0 V.

Mains frequencies can be monitored by pointing the sensor of the TH 2 at any electrical, intermittent light source and pushing the red key. The display shows you the supply frequency in Hz. An intermittent light source gives 100 pulses by 50 Hz mains frequency. The TH 2 bisects the amount of pulses and shows the frequency in Hz. If you leave the key the indicate will go out.

Camera speed will be measured by the optical sensor. The camera must be monitored by pointing the lens at a constant light source. The best light for measuring is daylight. Open the lens iris!

The monitor change frequency can also be measured by the TH 2. This is very important for filming of monitor-pictures to avoid the >> bar-effect <<.

Sensor:                              Photo-transistor
Elektronic:                        C-MOS-technology
Time-base precision         Quarz 4,1943 MHz ± 2 x 10-5
Meter-range:                    10 Hz to 99,9 Hz in increments 0,1 Hz
Read out:                           LCD-display, 13 mm high, 3-digits
Voltage:                             7-12V
Power drag:                       5mA in use
Size:                                   25 x 80 x 150 mm
Weight:                              220g 

Battery:                             9V E-Bloc

Black belt transport case with shoulder strap