This paper presents an experimental demonstration of a visible light communications link with an light emitting diode and a low-bandwidth organic photodetector as transmitter and receiver, respectively, that achieves sub $4\mathrm{Mbits}/\mathrm{s}$ speeds. An artificial neural network (ANN) equalizer is required in order to achieve such high data rates because of the influence of intersymbol interference. The digital modulation formats tested in this paper are nonreturn-to-zero on–off keying (OOK), and fourth-order pulse position modulation (4-PPM). Without equalization, data rates of 200 and $300\mathrm{kbits}/\mathrm{s}$ can be achieved for 4-PPM and OOK, respectively. With ANN equalization, data rates of 2.8 and $3.75\mathrm{Mbits}/\mathrm{s}$ can be achieved for the first time for OOK and 4-PPM, respectively.