As soon as Jobs got the call from Wozniak that Sunday afternoon, he knew they would have to get their hands on the technical journal right away. "Woz picked me up a few minutes later, and we went to the library at SLAC, the Stanford Linear Accelerator Center, to see if we could find it," Jobs recounted. It was Sunday and the library was closed, but they knew how to get in through a door that was rarely locked. "I remember that we were furiously digging through the stacks, and it was Woz who finally found the journal with all the frequencies. It was like, holy shit, and we opened it and there it was. We kept saying to ourselves, 'It's real. Holy shit, it's real.' It was all laid out - the tones, the frequencies." Wozniak went to Sunnyvale Electronics before it closed that evening and bought the parts to make an analog tone generator. Jobs had built a frequency counter when he was part of the HP Explorers Club, and they used it to calibrate the desired tones. With a dial, they could replicate and tape-record the sounds specified in the article. By midnight they were ready to test it. Unfortunately the oscillators they used were not quite stable enough to replicate the right chirps to fool the phone company. "We could see the instability using Steve's frequency counter," recalled Wozniak, "and we just couldn’t make it work. I had to leave for Berkeley the next morning, so we decided I would work on building a digital version once I got there."