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HUGO SACHS ELEKTRONIK - HARVARD
A P P A R A T U S
GmbH D-79232 March-Hugstetten Germany
HSE PLUGSYS
®
TAM-A Type 705/1 and TAM-D Type 705/2
6.1.2 Transducer calibration TAM-A
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The bargraph has one fix LED on position Zero, which is always on. A second LED may be on, anywhere
on the bargraph when there is no load on the transducer. Carry out an approximate zero adjustment
manually with the adjustments ZERO-COARSE first and then ZERO-FINE so both LED's overlap. If a
voltmeter is connected at the BNC output it should show as good as possible 0 Volt
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Start the AUTOZERO function by pressing the AUTO button in MEASURE MODE until the LED ZERO
goes on, for precise zeroing. The LED ZERO must automatically go off after a few seconds and not be
flashing at the end of the adjustment (no error, zero adjustment OK!).
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Using a pressure calibrator, apply the calibration reference e.g. 100mmHg to the transducer without alter-
ing the position of the transducer (zero error).
In the case of the example, the output voltage of ±10 Volt is equivalent to a measurement range of
±200mmHg.
Now take the litle red screwdriver which was delivered with the system and adjust on the
GAIN 20-100% trimmer the gain so that you get e.g. 5V (50% bargraph deflection)
which is equal to 5V on the output. The adjustment should be made in conjunction with
the recording device (recorder, data acquisition system, oscilloscope) or a commercial
vo l t m e t e r.
The larger the applied calibration reference, the more accurate the adjust-
ment can be made. The ideal situation is when the applied reference equals the measuring
range.
Tip
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The final step should be to check the zero again. The calibration reference load on the trans-
ducer is removed. The signal output of the TAM must then again be exactly zero. If this is not
the case, it is probable that application of the calibration reference load has shifted the trans-
ducer zero. A possible cause is a change in the position of the transducer, pulling on the
connecting cable etc. In order to achieve maximum accuracy it is necessary to repeat the
above adjustment procedure.
Important
The last step is to set the CAL value which can simulate a preset value on the TAM output. Set switch
CAL-OFF-MEASURE to CAL position. A freely set static calibration value e.g. 100mmHg can at any time
be simulated on the signal output of the TAM.
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Method 1: Adjustment using the recording device
With the TAM in MEASURE mode apply to the transducer, using the calibrator, the reference value you
want to simulate. Check for the reading of your recording device. On the TAM, switch now to operating
mode CAL. Turn on the CAL adjustment trimmer so that your recording device shows the same reading as
with the calibration reference before.
Easiest calibration can be made with connecting a digital voltmeter to the BNC output on the frontpanel.
Brief description in short form (example with a pressure transducer):
Wished range 200mmHg: which means 200mmHg should be equal to 10V at the BNC output.
Adjust Zero with transducer open to air, connect pressure calibrator and attach 100mmHg,
set GAIN so that you get 5V on the analog output.
Detailed description:
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S o r r y
In case the amplifier deflection is smaller than expected, the internal gain has
to be suitably increased. The procedure for transducer calibration as described
so far must then be repeated.
