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. Author manuscript; available in PMC: 2009 Oct 1.
Published in final edited form as: Int J Mass Spectrom. 2008 Oct 1;276(2-3):110–115. doi: 10.1016/j.ijms.2008.05.017

Figure 1.

Figure 1

(A) Analog circuit designed to measure the emission current of the EDD cathode. Q1 and Q2 are a matched pair of npn transistors. (B) Analog circuit designed to measure the extraction lens current. Q1/Q2 are a matched pair of pnp transistors, and Q3/Q4 are a matched pair of npn transistors. The electron current sourced by the cathode and sunk by the lens are mirrored and converted to a voltage by 10K resistors.