Knowledgebase Contact Us
How Can We Help?
< Knowledgebase

VTX Speed Controller

The VTX was one of our most popular 24v motor controllers which was also made in 12v, 36v, and 48v variants. It has now evolved into the DNO range which is electrically interchangeable with the VTX, except for the expansion connector. This page is for reference only.

4QD’s ‘VTX’ series are full feature Four Quadrant (acceleration and regenerative braking, forward and reverse) motor speed controllers for 12v, 24v, 36v and 48v battery operation. The range is economical enough for toy cars, yet powerful enough for use in golf buggies so it provides a very cost-effective solution for virtually every application which requires a reversing motor controller in the current range up to 100 amps.

Some possible applications are:- robots, invalid ‘scooters’, golf buggies, miniature railways, kiddiecars, floor cleaners, caravan shifters and vehicle loaders. The VTX-40 is the baby of the range, covering currents up to 50 amps. For more demanding applications the VTX-75 will give currents up to 100 amps. It is also possible to couple two controllers can be coupled so the two motors work as one, but with independent current limiting, giving control of currents up to 200 amps. This feature is popular with miniature railways where two engines are ‘double headed’. All models are available in 12v, 24v, 36v and 48v versions.

The VTX series are based on our tried and tested NCC series and are technically advanced and packed with useful features without the ‘high tech overkill’ which is often used as a sales gimmick. The controllers have been extensively ‘value engineered’ to give the best possible ratio of performance to cost. Of special interest are the independent, linear, adjustable acceleration and deceleration ramps, the ‘dual ramp’ automatic reversing, the thermally sensitive overcurrent limiting, the regen current limit, pot fault detection, ramp down at power off, reversing at zero demand speed and automatic reverse speed reduction.


Full specifications for the VTX can be found in the manual section of the website

Features and picture

24v motor

The diagram shows the features of the controllers.

Input is suitable for a standard 10K potentiometer. There is an on-board adjustment to alter sensitivity to suit different operating mechanisms. A connector is supplied. Various speed controls can be supplied as extras, including a spring-return-to-zero speed pot arrangement suitable for hand operation.

The circuit has fully automatic regenerative braking where most of the braking energy is returned to the battery, giving greatly extended use between recharges. With a regenerative brake the motor acts as a generator during braking. At zero speed the motor isn’t moving, so actual braking effect is zero, until the motor starts to turn. Regenerative braking can’t therefore always replace a mechanical brake since it doesn’t work well at slow speed. The circuit therefore optionally includes a driver for an electromagnetic parking brake.


  • VtxbxBox consists of a 5mm thick aluminium base/heatsink with a moulded plastic cover.


Several options are available. These are listed and marked:

  • C – Half speed reverse – user configurable Full/Half
  • C – Dual ramp or Preselect reverse.
  • F – Expansion connector: Two options: for double Heading or for Tacho feedback.
  • B – Regen Brake defeat. For quantity orders, the controller can be supplied without regen braking.
  • FVTX-40 Parking brake Driver and Thermal sensor may be fitted (already included on the VTX-75). Bulk orders only.
  • B – Reverse-ignition diode can be fitted on board. This is shown fitted in the wiring diagram for push button operation.

C – on board (user configurable)
F – factory options which must be specified at time of ordering.
B – options are available for bulk orders only

Wiring Diagrams

There are several wiring diagrams available:


You can download the instruction manual, in PDF format, via our manuals and catalogues page.