The circuit diagram below is of the railway's hand-held controllers.
All the parts should be available via either RS Components or Maplin.

| Component | Description | RS Cat. No. | Maplin Cat. No. |
| R1-R3 | 10kW resistor | 131-839 | M10K |
| VR1 | 10kW linear potentiometer | 855-462 | JM85G |
| D1 | LED (Red) - any size | ||
| D2 | 1N4148 diode | 271-606 | QL80B |
| D3-D7 | 1N4002 diode | 261-154 | QL74R |
| D8 | LED (Green) - any size | ||
| C1 | 10mF / 25V capacitor | 267-5139 | AT02C |
| TR1 | BC337 transistor | 131-1430 | QB68Y |
| TR2 | MJE3055 transistor | 313-6916 | |
| CB1 | 1 amp circuit breaker | ||
| S1 | Switch (DPDT) - ON-OFF-ON | 330-991 (toggle) | FH05F |
| Heatsink (for TR2) | 234-2328 | KU50E | |
NOTE: a heatsink must be connected to TR2 to prevent it overheating.