I took apart an old device board where I found several components that look like diodes. Can I use them? How do we know if they are diodes? Do the diodes spoil over time?
In principle, diodes have no expiration date. However, you need to know if they are really diodes and if they are good. The test with the multimeter must be done (see our instrumentation section). If they have low direct resistance and very high reverse resistance, they can be used. What you can't know is its maximum voltage and maximum current. By the size you can eventually evaluate the maximum current. In general, small diodes for general purpose are most useful.
