How do I set my input sensitivity? How do I know what my input sensitivity should be?

What is Input Sensitivity?

Input sensitivity determines how the SFT 881 reads the pulse signals from your turbine. It's important to set the correct sensitivity to ensure accurate readings, based on the strength of the signal produced by your turbine. Your turbine’s product specifications will indicate the appropriate signal level, which helps you choose the correct jumper position.

How to Set Input Sensitivity:

1. HIGH Sensitivity (Top Position)
   • Use this for low signal strength turbines (20 mV peak-to-peak).
   • Move the jumper to the top position if your turbine generates low-level signals.
2. LOW Sensitivity (Middle Position)
   • This is the default setting, suitable for most applications.
   • Use it if your turbine generates signals greater than 35 mV peak-to-peak.
3. TTL Sensitivity (Bottom Position)
   • Use this setting if your turbine signal has been processed by a signal conditioner and operates at TTL/CMOS levels.
   • Move the jumper to the bottom position for these applications.

How to Know Which Sensitivity to Use:

Check your turbine’s specifications for the signal strength it produces:

• For signals around 20 mVpp, use HIGH. Note that this setting is highly sensitive to electrical noise
• For signals greater than 35 mVpp, use LOW (default).
• If your turbine uses a signal conditioner, use TTL.

Important Note:

When using the High Sensitivity setting, it is recommended to use shielded wire from the turbine to the SFT 881. Signals at 20 mVpp are highly susceptible to noise interference, which can exceed 20 mV in noisy environments, causing unreliable readings. Proper shielding will help prevent noise from affecting the signal, ensuring more accurate data.