Anyone who knows me with even the tiniest of familiarity knows I am a proponent of manned space flight and a space flight history buff. I've often bemoaned the slow development of propulsion systems of the past decades. As a young man growing up in the internet generation, I've been shocked at how the computer industry can be changed by lone wolf programmers hacking their way over a few months (re: facebook, youtube, napster, bit torrent, etc..).
With the help of an electrical engineer friend of mine, we made the amplifier from a common op amp chip. There is a lovely website, here, that tells you exactly what resisters and capacitor values to use to set the gain and bandpass filtering you desire. We set our load cell amplifier for a 20 gain and a 300 Hz low pass filter. The image above left shows the configuration on the chip pins, and the image above right shows the whole circuit with power supply and indicator lights.