LEGO 9V Light brick (via RCX)

Status: ✅ works (rcxvll.nqh)

The LEGO 9V light/lamp brick is the most LEGO-native VLL emitter: hooked to an RCX output port and flashed in the VLL timing, it commands a Micro Scout.

How it works

• This is the approach in rcxvll.nqh (pbrick): NQC macros (vll_init/start/0/1/stop) toggle the output, preamble = 400 ms, unit = 20 ms, full VLL opcode table.
• Pure LEGO hardware, no electronics — but needs an RCX + tower to drive it.

Best for

Doing it the period-correct, all-LEGO way if you already own an RCX.

Links

• Ben Jackson — VLL Transmit for legOS — a related legOS method that drives the LED inside the RCX light sensor, not a lamp on an output port.
• rcxvll.nqh (pbrick)