Want to conduct experiments and tests on a CAN bus? You can with this DIY CAN tester, which also offers the option of connecting an existing CAN bus.

This is a multifunction RJ45 network cable tester. It is the design of the network cable (RJ45) test, and telephone (RJ11). It is cheap and easy to use.

Want to repurpose an operational amplifier from a previous project or an old parts collection? You can construct a specialized op-amp tester quickly.