MPHDev's Famicom Power & AV Board allows you to output a composite signal from your Famicom to be able to connect it to modern TVs.

But it also allows much more:

• Consumes and heats up less: Uses a bucket voltage converter rather than the linear LM7805 voltage converter which dissipates part of the energy into heat
• Protection with an easy-to-replace 1.5A fuse
• Supports power supplies with the + in the center or outside, from 9V to 40V
• No jailbars (*), the amplification circuit is the same as the Famicom original AVs
• Compatible with 2 motherboards (HVC-CPU-07 and HVC-CPU-GPM-02)
• Supplied with AV cable and transformer

(*) Depending on the console (PPU model, age of the capacitors, etc.) and the installation mode, there may be some slight jailbars.