Found in a PE Hobbyst Handbook of 1991, this circuit was originally proposed to time photographic baths in developing rooms but can be used for other purposes. The circuit beeps at 30-second intervals.
This circuit is from an ancient American documentation. The T-Bridge circuit determines the...
This configuration is from a 1964 US documentation valid for any FET. The range of power voltages...
This instrumentation amplifier with differential inputs was found in documentation from the 90s....