Model Locos

Loco Wiring: Auto Reversing Lights

Some models have separate forward and reverse lights that need to change automatically when reverse is selected. The 4 relay version of the HRB can be configured to do this by following the diagram below. Read More

Noise Suppression for Multiple Motors

One question that often comes up is how to best arrange the motor noise suppression components on locos that have multiple motors driven from a single controller and spread across two or more bogies. There Read More

Double Heading Pro & 4QD Series

A lot of customers are now seeking to double head [or MU] locos with different models of 4QD controller, and a common request is how to link a new Pro-160 / 360 to an older Read More

Sound System Suppliers

We often get asked about sound system suppliers, so here’s a list of all those that we know about. Brian Jones Dallee Electronics Mtroniks Phoenix Sound Sense Innovations Soundtraxx South West Digital Trax Controls These 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

Clubs with controller test boards

Here’s a list of all the clubs that have a controller test board… Ashmanhaugh Light Railway Belfast & County Down Miniature Railway Society Bromsgrove Model Engineers Budmouth College Camp Creek Railroad Cleveland Association of Model Read More

DCC / Airwire Interface

We’ve been asked by a number of customers if our controllers can be made to work with a DCC orĀ  Airwire system. This little circuit ought to do the trick…. With pins 2 and 3 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

Mtroniks and regen braking

One of our customers has brought to our attention an issue that can arise when using an Mtronics sound card with a controller that has regenerative braking [all 4QD controllers]. The model in this case Read More


Towing an electric vehicle with a permanent magnet motor can cause major problems. If any E.V. is to be towed, you must disconnect the motors or else jack the machine so that the drive wheels Read More

Phoenix Loco Wiring

4QD supplied the complete wiring for Phoenix locos and the wiring of the loco is shown here for the convenience of Phoenix customers. This equipment was supplied only through Phoenix and enquiries about the locos Read More

Loco Wiring: Hand Control & Horn Relay Board

4QD’s Reversing Bell throttle hand control and associated Horn Relay Board are designed to simplify miniature Loco wiring whilst maximising features available. The Reversing Bell throttle gives a dead man speed control and may be Read More

Double Heading Problems

Systems using the expansion connector to double head with a pair of controllers (Pro-150 or Pro-120 or DNO or VTX) almost always simply work when wired correctly. But there are occasional problems with installations: Wrong Read More

Double Heading Switch

We were asked for a system such that either loco could be at front and could be facing either way. This seems to make selection of reverse very complicated, but it is in fact quite Read More