Intercom with telephone (CB7829E)

Old phones with dials can be used in a simple home intercom system, as this circuit from Popular Electronics from the 90's shows.

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Remote thermometer (CB9487E)
We found this circuit in a 90s Linear Technology documentation. The circuit uses components from...
PWM motor control (CB7996E)PWM motor control (CB7996E)
This circuit for some amps was found in a 90s Radio Electronics. The voltage can be between 6 and 25 V...
High Voltage SCR Alternating Source (CB13208E)
This circuit supplies a load with pulsating direct current that can be filtered by C1 (10 uF to...