L7809CV 3-Terminal Positive Linear Voltage Regulator

A three-terminal fixed regulator producing a stable 9V output from a higher input voltage - used for audio circuits, effects pedals and equipment specified at 9V. It needs only two small capacitors to work and is essentially impossible to get wrong, which is why it has been the default choice for decades. The trade-off is efficiency: every volt of difference between input and output becomes heat. Dropping 12V to 9V at half an amp means real power dissipated, so a heatsink is required at anything above light load. Where efficiency matters, use a switching buck converter instead. Stable 9V output with only two external capacitors; Built-in thermal shutdown and short circuit protection; Extremely reliable and simple to design with; TO-220 tab bolts directly to a heatsink