This filter is from the Linear Applications Handbook of the National Semiconductor of 1994. However, it can be used with other operational and modified to operate with other frequencies.
This powerful inverter provides a high-quality sine wave signal. I found it in a Radio Electronics issue...
We found this circuit in a Popular Electronics of the 90s. The circuit still uses light bulbs, but...
The relay used in this circuit must be of the sensitive type with a trigger current less than 10...