Suggested by National Semiconductor in documentation from the 90s, this circuit makes use of an operational of the time. The configuration can be applied to modern equivalent components
This circuit was obtained from an old American documentation, and practically any general-purpose transistor...
This circuit is intended for monitoring an environment. It fires a relay with a sound, but only if...
This circuit is from an old documentation, but perfectly current. In place of the battery, 2 or 4...