Current models

Pro-160 / 360 Dual Control

We were asked if it was possible to have dual joystick controls on the Pro-160 / 360 to allow interior and exterior helm positions on an electric launch installation. This diagram shows how we did Read More

Pro-160 / 360 Radio Control Failsafe

When using the Pro-160 / 360 with radio control it is necessary to consider the various failsafe scenarios that can occur. The Pro-160 / 360 will detect the following A break in the connection between Read More

Pro-160 / 360 to JSK-100 wiring

This diagram shows how to hook up one of our JSK-100 joysticks to the Pro-160 / 360. The Pro-160 / 360 should be set to volt mode and joystick mode, and then use pot learn Read More

Pro-160 / 360 Failsafe Contactor

This page shows how to incorporate a failsafe contactor into the wiring for the Pro-160. The same schematics also work for the Pro-360 but the J1 link is in a different position. Method 1 – Read More

Double Heading the Pro-160 / 360

Here’s a schematic of how to connect two Pro-160s or 360s together for double heading [master / slave operation. The ignition wires are kept seperate to prevent stray currents causing damage to the controllers if Read More

DNO Fault Finding Guide

This is the fault finding guide for the DNO range of controllers. The DNO is the end result of a long line of 4QD analogue controllers including the NCC and VTXs. It is therefore a Read More

Pro-160 / 360 Software Versions

This is a list of the formally released Pro-160 / 360 software versions. The Pro-160 and 360 use the same control board with largely the same software. Each software version has a number of different Read More

Pro-160 / 360 Fault Codes

The Pro-160 and Pro-360 have a number of warning messages or error codes that can appear depending on what the controller thinks is happening. This table lists; the code any associated sound signal whether the Read More

DNO and Sound Cards

When using DNO with a sound card you will need to give the sound card a signal that relates to the speed of the model. There are a number of ways to do this described Read More

Pro-150 Hall Throttle Supply

The Pro-150 can easily be programmed to work with a voltage output from a hall type throttle. What takes a little more thinking about is where the feed for that hall device comes from. It Read More

How To Wire Up a Porter 5

We were asked if we could make some videos on how to wire up our controllers. First up is Dillon demonstrating how to wire up a Porter 5 controller. Dillon was our first work experience Read More

Control Board Jumper Positions

This picture shows the factory default control board jumper positions, these allow single ended operation. For joystick [wig-wag] operation move J1 and J2 to the opposite positions.

DNO Current Limit Adjustment

As standard the DNO-5 and DNO-10 have their current limited to approx 50A and 100A respectively. These values are controlled by the value of the DNO current limit adjustment resistor R25 in the diagram below, Read More

Closed Loop Current Control

Although our Porters have current limiting which can be adjusted, they were not really designed to provide an active closed loop current control mode. So many thanks to Ian Beaver for making public a neat Read More

Pro-150 Hall Throttle Programming

This page describes how to use the “pot learn” feature of the Pro-150 to set it up for operation with a hall effect throttle. Before starting this sequence the Pro-150 should have power connected to Read More

Pro-150 with shunt wound motors

Here’s a diagram showing how to use the Pro-150 with shunt wound motors. The principle is to use the brake driver on the Pro-150 to activate a relay that feeds the field winding, and to Read More

DNO Under Voltage Protection

Although the DNO does not have an under voltage protection cut-off fitted as standard it is easy to retro-fit this feature. There are two ways to do this; Method 1; the easiest, is to cut Read More

Pro-150 Push Button Use

If you need to control a Pro-150 via forward / reverse push buttons, a neat way to do it is to use the Pro-150 in joystick mode. This diagram shows how to wire it up. Read More

Ampflow motor

We recently encountered a strange issue with a 4QD-300 driving an Ampflow A28-400-F24 motor. Forward operation worked as expected but in reverse a very slight pulsing or oscillation of the motor speed could be detected Read More

Pro-150 Fault Finding Guide

We’ve written this guide to help customers diagnose and fix problems that may occur with the Pro-150. We don’t release complete circuit diagrams for current models but we hope this guide will shed some light Read More

Damage From Blown Mosfets

It doesn’t happen often but when the mosfets in a 4QD series controller do blow they can take a number of other components with them. If you are attempting a DIY repair this photo shows Read More

DNO Version history

The DNO PCB number is 30-2D-01. The following is a list of modifications listed by serial number. The DNO was originally designed to block transition from ahead to reverse without reducing the throttle to zero. Read More

Disabling regen braking [DNO]

Although the DNO is very similar to the VTX, one feature that it does not have is the provision for disabling regen braking via on-board links. A number of people have asked if it is Read More

Double Heading Wiring Diagram [DNO]

This diagram shows how to connect two DNOs in different model locomotives together using the expansion port.     You can download a PDF version here. For the slave cable we recommend using a bulgin Read More

Battery Contactor

This optional battery contactor arrangement can be fitted as part of the 4QD-200/300 installation to provide reverse polarity protection and also an emergency power disconnection. The relay should be chosen so that it is capable Read More

Porter Current Limit Adjustment

It is possible to adjust the Porter current limit setting by fitting either a fixed resistor or a potentiometer across the pads circled in red below A resistance of 100k gives a motor current limit Read More

Driving the DNO by Raspberry Pi

Our DNO range is ideally suited for use as an interface between a Raspberry Pi, Arduino  etc, and a motor. The Pi can provide a PWM output via its GPIO pins and this can be Read More

Pro-150 Pt Fault Code

If a Pro-150 gives the Pt [pot top] fault code, or just gives a continuous rapid beeps, this indicates a pot or wiring fault or blown F1 fuse track such that the voltage on the Read More

Adjustment for 48V

Unless specifically requested for 48V, we usually configure the 4QD series for 24V operation. When operating at 48V the acceleration ramp control may need to be adjusted as well as the gain control in order Read More

Pro-150 Mechanical Information

Pro-150 mechanical information Dimensions Board only: 145mm x 102mm x 38mm With base and cover: 181mm x 121mm x 46mm Weight Board only: 320 gm Complete: 630gm Power connectors 9.5mm push-on for battery, combined with Read More

Pro-150 Basic Wiring Diagram

This diagram shows a basic wiring scheme for the Pro-150 running on 24V with ignition and reversing switches. For clarity we haven’t shown the optional display / programmer which connects via 2 cables to its Read More

Overheating in Boats

If you are using the 4QD series in a boat then you should pay particular attention to airflow and cooling to prevent the controller from overheating. It’s not kind to shut your controller away in Read More

Use with Series Wound Motors

Our controllers are principally designed for Permanent Magnet motors, but they can be made to work with series wound motor with some modifications to the wiring. To control speed and direction of a Permanent Magnet Read More

Converting Parking Brake to Brake Light

The 4QD series has a Parking Brake solenoid driver. Optionally controllers can be supplied from the factory with this converted to a ‘Braking’ Light driver. This page describes the modification. Warning. The parts that need Read More

Inhibit Ramp Modification [4QD series]

The inhibit input on the 4QD controllers is designed to be used in conjunction with a microswitch sensing the foot brake on an electrical vehicle. Our features area explains this operation of the Foot-Brake inhibit. Read More

Deadband values and removal

This page specifically refers to modifying pre issue 15 boards. From issue 15 onwards there is an on-board jumper to alter the deadband. With issue 17 boards, the half-speed reverse feature was changed to make Read More

How to dismantle the 4QD series

Hopefully you’ll never have to do this, but if the need arises then here is how to do it. Top board removal. Remove the top board by loosening the four corner screws. Disconnect the 14 Read More

Fault finding on the 4QD series

4QDs policy on all controllers is one of continuous modification. If we find a mechanism whereby a user can blow a controller, we modify the design if possible, to prevent it happening. This means that Read More

Testing the 4QD Base Board and MOSFETs

Bridge testing Method All testing of faulty controllers should be done on a current-limited bench power supply: testing a faulty controller from a battery will almost certainly exacerbate the fault, causing yet more damage. The Read More

Current limit resistors

Notes on the current limit resistors for the 4QD series. The control board current limit resistors have changed frequently, as MOSFET improve the Rds generaly decreases. This increases the current, but it has to be Read More

Use with Tacho Feedback Board

The circuit of the standard tacho-generator feedback board is described on the site and a drawing with other information is available. Mechanically, this board is designed to plug into the NCC and Pro series Read More

Control Board Modification [Pre June 2010]

Control board modification This page details two modifications The first part should be done to all controllers with serial numbers below 4028. After that, the modification was included in production. Modification is to the top Read More

Reverse Speed Modification [pre issue 17]

How to adjust the maximum reverse speed on earlier 4QD control boards. This information applies to earlier 4QD series only. With issue 17 control boards the method of incorporating half speed reverse changed. It is Read More

Mixing 4QD 150 / 200 / 300 series boards

With several ‘caveats’, the control boards and base boards of the 4QD series are interchangeable and may be mixed and matched. However – it is important that you understand the potential problems. 4QD 300: This Read More

4QD version history

This page lists the different versions of the 4QD series circuit boards, and their date of introduction. This listing was originally generated for 4QD internal use only so the descriptions may not be as full Read More

DMR-203: Use with PRO-150 Controllers

The DMR-203 may be used with Pro-150 controllers. There are two ways of doing this. One involves a slight modification if the DMR but has simpler wiring. The second does not involve modifying the DMR, Read More

Pro-150 Capacitor Modification

This modification should be applied to all Pro-150 controllers with serial numbers 0198 or higher and lower than 0550. On 0550 and later controllers the capacitor is not fitted. On serial numbers 0198 and lower Read More

PRO-150 Current Limit

The circuit of the Pro-150 is available as a pdf. Current limit amplifier is in the bottom right corner. Current is monitored by sensing the voltage drop across the lowside MOSFETs when they are conducting. Read More

PRO-150 Issue History

These notes are by serial number, rather than by date. The list is mainly for 4QD internal reference so is somewhat technical. 0000 to 0105 Are Mark 1. In these, there was no 12v connection Read More

Positional Servo Control [DNO / VTX]

Notes on how to create a positional servo control. There are two types of servo system: speed and position. These are explained in our Answers to FAQs on Battery Motors & Controllers. There is also Read More

Wiring for Push Button Use

This diagram shows how to connect a Pro or DNO (or earlier NTX and NCC) series controller for push button use, or with a centre-off switch. Note that the diode shown between the buttons must Read More

PRO-150 Joystick Programming

This page describes how to use the “pot learn” feature of the Pro-150 to set up joystick programming, [or wig-wag operation]. Before starting this sequence the Pro-150 should have power connected to B+ and B-, Read More


These notes apply to the inhibit function of the 4QD series controllers. If a vehicle is fitted with a hand or foot brake, it can be useful to disable the controller. This can be done Read More

Multiple Controllers [Double Heading]

This page describes wiring that allows multiple Pro-150s and 4QD series controllers to be controlled from a single speed potentiometer. This is useful when double heading model locomotives. As the Pro-150 is a programmable controller, Read More