Oscilloscope
Always check your earthing
04/09/26 13:08 Filed in: Hardware
The modern DSO (Digital Storage Oscilloscope) is a powerful diagnostic instrument well suited for diagnosing hardware but there are traps for young players the most insidious of these is differing earth potentials. If you get this wrong you can easily release the magic smoke from a circuit and worse still put your life in potential danger.
This week's adventure started with a Rigol DHO924S a perfectly adequate 12bit 1.25GSa/S scope for most tasks (except for the one I really want to use it for) and just before connecting up the signal probe earth to the USB powered microcontroller circuit I did my usual check with a multimeter of the difference of the zero volt on the circuit under test and the signal probe ground wire. 88 volts. A scarily large number for a sensitive device under test. While in this case the connection would probably have been safe, good practice made me change the supply arrangement - just in case. Read More...
This week's adventure started with a Rigol DHO924S a perfectly adequate 12bit 1.25GSa/S scope for most tasks (except for the one I really want to use it for) and just before connecting up the signal probe earth to the USB powered microcontroller circuit I did my usual check with a multimeter of the difference of the zero volt on the circuit under test and the signal probe ground wire. 88 volts. A scarily large number for a sensitive device under test. While in this case the connection would probably have been safe, good practice made me change the supply arrangement - just in case. Read More...