 Wed Jan 14 12:02:04 2009, Stefan Ritt, External Trigger Input requirements 
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Several people mentioned that the external trigger input (TTL) does not work on the DRS4 Evaluation Board Rev. 1.1. This is not true. The requirement
however is that the input signal must exceed approximately 1.8V. Since the input is terminated with 50 Ohms, not all TTL drivers may deliver enough current
to exceed this threshold. To verify this, the trigger signal can be monitored with an oscilloscope at test point J24. Only if the input signal exceeds |
 Wed Jan 14 13:41:44 2009, Stefan Ritt, External Trigger Input requirements
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Another tricky issue comes from the fact that the external TTL trigger and the comparator are in a logical OR. So if the comparator level is set
such that the signal is always over the threshold, the trigger is always "on" and the TTL trigger does not have any effect. It is therefore necessary |
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Mon Dec 15 13:37:38 2008, Stefan Ritt, Welcome
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