I graduated with a Masters of Engineering, concentrating in digital signal processing, in particular medical and audio, almost two years ago. I've always been interested in research, but due to personal circumstances I could never commit a lot of time to working on a research project with a professor, and obviously didn't get a chance to publish anything. Now that I'm more settled and have much more time on my hands, I started getting involved in some open source projects and reading some technical literature (engineering, mathematics) that I couldn't get to before. However, I'd still like to find someone to to collaborate with on a research project who is already established in the field and publishes papers. Part of the reason I want to do that is to be able to eventually apply for a Ph.D. program in a good school, and having publications would be a great thing on my resume.
What I'm trying to find out is how I can work on a research project similar to those graduate students work on as a part of their studies if I'm not a student anymore? Should I contact my old professors from the university? Is it possible to find some "open research" team that accepts collaborators from outside? Do I have to do it on my own (quite frankly I'm not sure I can give myself a good enough quick-start)? In short, I'm willing to volunteer my time in exchange for a possibility of publication in the future. Can I do it, and if yes then how?