Apogee TS-100 Owner's Manual - Page 11

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OPERATION AND MEASUREMENT

Connect the temperature sensor or RH probe sensor to a measurement device (meter, datalogger, controller). If

you are using the ST-110, this device must be capable of inputting 2.5 V DC, and measuring and displaying or

recording a millivolt (mV) signal (an input measurement range of 0-2500 mV is required to cover the entire

temperature range of the ST-110 air temperature sensor). In order to maximize measurement resolution and

signal-to-noise ratio, the input range of the measurement device should closely match the output range of the

sensor.

Connect the fan to a 12 V DC power supply capable of supplying at least 80 mA. If the datalogger has the capability

for pulse width modulation (PWM) it can be used to reduce fan speed at night or under conditions of low solar

radiation and/or high wind speed. The datalogger or controller must have a pulse width modulation (PWM) output

of approximately 20 kHz and a duty cycle of 50 to 100 %.

The tachometer output is measured by a pulse counter. The tachometer also requires an input voltage, where

maximum voltage output to the pulse counter is the input voltage to the counter. The tachometer output allows

monitoring of the fan to ensure it is functioning properly.

The following instructions are for the ST-110 thermistor included with the TS-110 option. For wiring other sensors,

including PRT sensors, please see their respective manuals.

VERY IMPORTANT:

Apogee changed all wiring colors of our bare-lead sensors in March 2018. To ensure

proper connection to your data device, please note your serial number or if your sensor has a stainless-steel

connector 30 cm from the sensor head then use the appropriate wiring configuration below.

Wiring for ST-110 Serial Numbers range 0-2724

Plug each wire into the appropriate data logger terminal following the illustrations below:

Thermistor

Measurement devices (e.g., datalogger, controller) do not measure resistance directly, but determine resistance

from a half-bridge measurement, where an excitation voltage is input across the thermistor and an output voltage

is measured across the bridge resistor.

Red: Excitation Channel (excitation for

thermistor)

Black: Single-ended channel (positive

thermistor lead)

Blue: Analog Ground (negative thermistor

lead)

Clear: Ground (shield wire)