I enjoy doing kitchen engineering with my kids. We were looking to do a robotics experiment which would require a linear solenoid actuator to continuously pump. I thought it would be simple until I realized that I would likely need a 555 chip(?) and some skills with circuitry...which would be fine if that was the lesson for me and my kids. Basically...anybody know where I might purchase a linear solenoid that is in the astable position. They seem surprisingly hard to come by? Thank you! Sorry this isn't an academic question.