The R/C Mini 4WD R/C System TRT-1/TRR-1 (Japanese: ラジ四駆 RCユニット（TRT-1/TRR-1), Raji Yonku Ārushī Yunitto (TRT-1/TRR-1)) is a Mini 4WD Grade-Up Parts released by Tamiya on August 7, 2002.
The parts was specifically designed for the TR-1 Chassis.
The set includes a TRT-1 remote control transmitter and a TRR-1 receiver. The transmitter was powered by a PP3 9v battery, while the receiver (when installed into the TR-1 Chassis) was powered by a pair of AA batteries that are also powers the Mini 4WD cars.
The system used 27 MHz frequency range, but instead of using matched pairs of replaceable crystal quartz oscillators, it used matched pairs of transmitters and receivers with built-in oscillators due to strict size and weight limitations for receiver modules. The R/C system has five different frequency bands, designated by five colors. Each set has a designated color on transmitter button, receiver antenna tip and round sticker on the receiver body. Every competitor must use different frequencies for each car to avoid crosstalk problems; as there are five available frequencies, up to five cars can compete at a time. The assigned bands' colors and frequencies are as follows:
- Ad-1: Blue, 26.995 MHz
- Ad-2: Green, 27.045 MHz
- Ad-3: Yellow, 27.095 MHz
- Ad-4: Red, 27.145 MHz
- Ad-5: White, 27.195 MHz
The R/C system turns a R/C Mini 4WD car into what most people described as a remote control slot car when the receiver is installed into the car. The car will only accelerate if the racer pushes and holds the button on the transmitter. This way, racer can particularly control the speed of the car as they want. Due to it's simplicity, the system does not have the capability of continuous speed control or active motor braking.
Unfortunately, it comes with a price: Because of the low motor powering voltage and high current, switching losses becomes more significant. Also, adding the receiver into the car will add more weight to the rear of the car, making it unbalanced.
As of current race regulation, the use of the R/C system is not allowed on most Mini 4WD race tournaments. However, they are required for R/C Mini 4WD-specific tournaments.