Suggested for use in cars and motorcycles, this circuit was found in a 90s Popular Electronics. The MOSFET can be anyone that supports the current of the lamps. Adaptations can be made to use LEDs.
Today we have more compact solutions. This is from a Radio Electronics magazine from October 1990....
This filter was found in Texas Instruments documentation from the 1980s. The circuit uses a common...
16 commercial test circuit for tubes and transistors appeared in Radio Electronics magazine in...