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Home Book Chapters Chapter 5 - Wave-Particle Duality Simple d.i.y. Low-Pass Filter for Interfacing PMT Amplifier to PC Sound Card (Used with Free “Pulse Recorder and Analyser” Software MCA)
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Simple d.i.y. Low-Pass Filter for Interfacing PMT Amplifier to PC Sound Card (Used with Free “Pulse Recorder and Analyser” Software MCA)

diy low pass filter interface between photomultiplier scintillation probe amplifier and PRA by David Prutchi Ph.D. www.diyPhysics.comFigure 34 in the book shows the schematic diagram for our photomultiplier tube (PMT) signal processing circuit has an analog output that is suitable for use with a sound-card-based multichannel pulse-height analyzer (MCA).  However, if you already have a commercial scintillation processor that you would like to use with PRA, then you will somehow need to extend the typically narrow output pulses (e.g. 1 to 10 microseconds) so that they can be acquired through the sound card.

The simplest method is to use a passive low-pass filter.  We built ours from a 100 Ohm resistor and a 0.56 uF capacitor (total capacitance of the two parallel capacitors shown in the picture below.  We assembled the filter inside a Pomona Electronics 3752 mini enclosure with BNC connectors, which provides appropriate shielding from noise, as well as an easy way to inserting it in-line between the pulse processor and the PC’s sound card input.

diy low pass filter interface between photomultiplier scintillation probe amplifier and PRA by David Prutchi Ph.D. www.diyPhysics.com

 

 

Please visit www.diyPhysics.com and www.prutchi.com for other cutting-edge d.i.y. projects, and remember to check out our new d.i.y. Quantum Physics book:

 
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One Response

  1. Hi –

    Just had a quick question about sound card spectroscopy –

    I have a couple of ratemeters that can easily hook up to a scintillation probe and have a pulse output. For example, one is a Ludlum model 177 with a BNC connector for “Pulse output” – would this work for the sound card data acquisition? And would it need a low pass filter?

    I also have some ratemeters with a simple pulse output for audio. It seems like that would be a long enough pulse, since it is audible, but I have no idea if that pulse output is actually providing the pulse height coming from the tube or is just giving it at a constant amplitude to drive a speaker.