diff --git a/ohmpi/hardware_components/mb_2024_0_2.py b/ohmpi/hardware_components/mb_2024_0_2.py
index d7f685e4287b6420afb47503616dc21ee73cdf6a..c0be4c5583959483a0de457bbf9f832f4bb5ec4a 100644
--- a/ohmpi/hardware_components/mb_2024_0_2.py
+++ b/ohmpi/hardware_components/mb_2024_0_2.py
@@ -76,7 +76,6 @@ class Tx(Tx_mb_2023):
         # add leds?
         self.pin6.value=True
         Tx_mb_2023.inject(self, polarity=polarity, injection_duration=injection_duration)
-        print(self.polarity)
         self.pin6.value = False
 
 
diff --git a/ohmpi/hardware_system.py b/ohmpi/hardware_system.py
index a8a244363f6ac81eac655055564ffec7b1998c26..50e41c0a88e011f65743605eb2ff71974a539b02 100644
--- a/ohmpi/hardware_system.py
+++ b/ohmpi/hardware_system.py
@@ -439,7 +439,7 @@ class OhmPiHardware:
         if polarities is not None:
             assert len(polarities) == n_pulses
         else:
-            polarities = [-self.tx.polarity * np.heaviside(i % 2, -1.) for i in range(n_pulses)]
+            polarities = [-int(self.tx.polarity * np.heaviside(i % 2, -1.)) for i in range(n_pulses)]
         if not append:
             self._clear_values()
         for i in range(n_pulses):