Uncategorised - 4QD - Electric Motor Control

Motorised Wheelie Bins

The guys over at Nervous Squirrel have used some of our Pro-160s to drive these funky motorised wheelie bins. They are for the Bureau of Silly Ideas – a street theatre company and we’re hoping to see them in action soon.

motorised wheeli bins

There’s a video of them in action here.

Price Increases

We really don’t like having to write this post but we do need to let you all know that we along with the rest of the electronics industry are facing significant component price rises and supply problems which are having a material impact on our costs.

Throughout 2021 we managed to absorb these increases, but the global supply chain issues are now really starting to affect us as much any other industry.
One voltage regulator chip has gone from £1.50 to £8.50 [we’re lucky that we’ve managed to secure supplies], the aluminium that we use for heatsinks has jumped by 50%, and our electricity costs have just doubled. Lead times for many components are now over 12 months and some are difficult to get hold of.

The good news is that we’re pretty sure of our supply chain for 2022, we’ve invested a lot in increased inventory of the key components, and have updated our planning tools. Our PCB company has been really helpful with scheduling call-off orders, and we’ve bought in bulk where possible to get better price breaks.

But the bottom line is that we will need to increase prices from 1st Feb 2022. We’ve worked hard to keep the increases as low as we can, and if our costs come down then we will reduce our prices to keep the same margin.

Di-wheel Case Study

Here’s a case study that we’re really rather proud of. V O Vehicles asked us to design the control system for this unique pedal / electric, solar charged di-wheel taxi that they launched at the recent CENEX exhibition. The vehicle is quite complex with pedal torque sensing, a joystick for steering and reverse, a removable battery, and a phone as a display. We helped VO understand the options and trade-offs around the battery and motor, and also on how the different controls could be integrated. Our solution uses two of our Pro-160 controllers with the input signals being handled by our new dual channel interface module and a custom scaling board.

VO diwheel
VO electric diwheel

Pedal Car Conversion

We just love the colours of this pedal car conversion that one of our customers has done.

pedal car conversion

It’s using a Porter 10 and a pretty beefy LiPo pack so it should shift a bit!

Dual Channel Interface

It’s here….our new dual channel interface. This nifty board allows you to control two of our DNOs or Pro series from a dual axis joystick. It gives true single-handed control of speed and direction in skid steer vehicles. We used to make an analogue version of this years ago but this one is digital which makes it much more versatile. It can accept pot or hall inputs, and can operate with the throttle in center-off or single ended mode. The steering sensitivity can be adjusted via the trim pot. If you’re building a ride-on tank or Banana Splits type buggy this could be what you need.Digital dual channel interface


Throttle Lever

We’ve been looking for a cost effective throttle lever for ages now and not found anything suitable, so we thought we’d have a go at building our own. 3D printed in tough rPETG, it’s got removable end stops and center detent. All metal parts are stainless, and it has a hall sensor that’s good for 10 million cycles. Easy to dismantle and all parts are replaceable.  The end result is a substantial, chunky, throttle lever designed for applications where the odd knock is expected.

hall effect throttle lever

Electric Motor Dyno

Here’s an electric motor dyno we’ve been working on for a customer. It’s using a brushed motor to provide a load for a brushless one. We’re using our new rpm control software in a Pro-160 to manage the load speed while the torque is measured by the sensor.

electric motor dyno

The motor on the left is the load, it was surprising just how warm it got after only a few minutes operation.

Pro-360 High Power Controller Launched

Our new Pro-360 is now in production. We’re really chuffed that it’s only taken a little over 6 months to go from concept to launch. Using the control board from the Pro-160 meant that we could re-use most of the software, and using the metalwork from the 4QD-300 gave us proven high power hardware. If you need a high power controller with lots of features come and have a look.

Pro-360 and cover

Electric Super Moto

Billy is working on this really stylish electric super moto. It’s running one of our new Pr0-360s so he will be able to take the voltage up to 84V in due course which should give around 30kW. It’s also capable of having a fully mapped throttle, torque limiting, and lots of other clever stuff in the software.

Electric super moto
Electric super moto [Pro-360]
Oh, and he’s done a lot of the videos on our site for us, if you like his work we can put you in touch.

Funicular Railway

Henry has built this ingenious funicular railway to haul building materials to his house. It uses a chain and gypsy drive arrangement controlled by one of our 4QD-300s. We’ve also supplied a contactor arrangement that provides a failsafe regen braking system.

4QD & Covid-19

We’re still here, open as usual!

If you’re fed up with the Covid 19 news, self-isolated, or just plain bored, why not give us a call to talk about your next motor control project and how we can help get it moving?

Also to re-assure all our customers, our supply chain has minimal exposure to foreign suppliers, we’ve got good stocks of parts for all of our products, and our team is hale and hearty.

we'rfe open



Pro-360 High Power Controller

Here’s a sneaky peak at the first prototype of our new Pro-360 high power controller. We wanted the feature set and voltage rating of the Pro-160 coupled to the brute current handling of the 4QD-300. We’ve used the control board of the Pro-160, and created a new power board that uses the same heavy duty bus bar and heatsink structure of the 4QD-300. The result – a digital H-bridge controller that can go up to 96V, 360A, and that has liquid cooling available. Now I’ve just got to build a rig capable of testing this monster!

highigh current pwm controller

Joystick Control

The guys at Riverside Miniature Railway asked us if we could come up with a solution to help a lad with restricted mobility be able to drive a loco. We eventually settled on the joystick control you see in the picture, a custom profile for our Pro-160, and a deadmans handle button for the guard.

It all worked a treat – here he is taking his mum for a few laps of the track wearing the biggest grin I’ve seen for a while!

Joystick control system for model loco driver

Porter 3 Speed Board

We were asked by a Greenpower team to come up with something to help equalise the power available to all three drivers. All too often we see the first driver going hell for leather only for poor old number three to end up looking like the proverbial Miss Daisy and grinding to a halt after 85 minutes. This board plugs in between the normal throttle arrangement and the Porter, and can be used to restrict the power available to each of the first two drivers. Alternatively it can allow multiple engine modes i.e. “normal”, “pass”, and “all out”.

Porter 3 speed


Pro-160 Launched

Yep it’s finally happened – our Pro-160 has started to roll off the production line.

Our Pro-160 has now been launched

Pro-160 with split display adaptor
Pro-160 with split display adaptor

We’re really pleased with the way this controller has turned out, it’s a stronger, smarter, and better looking brother to the Pro-150.

We set out to design a controller with all the features you’ve been asking us for. The brief was for a full H-bridge controller to do away with reversing relays for long term reliability, you wanted full control over the motor current in both drive and regen modes, and you also wanted lots of inputs for radio control, temperature and speed sensors, dead-mans handles, and limit switches etc. You also asked us for a wider voltage range, so we’ve made one that works from 12 – 84V.

We gave it a unique detachable display that you can mount conveniently to show you exactly what your motor and battery are doing.

A single switch lets you quickly switch between any two profiles, e.g. fast / slow, or handset / RC.

Oh, and we also added a uSD card slot to make adding new features via software updates easy.

All of this adds up to a highly versatile controller ideally suited to a wide range of hobby and industrial users.

Think it’s safe to say mission accomplished!……. come and have a look.


4QD Options


Custom Product Settings


Product Settings


Water Speed Record

Here at 4QD we like boats, fast things, and particularly jet engines. So when we got a call from the guys at Project Longbow we were tickled pink! They are putting together a jet powered hydroplane for a serious assault on the world water speed record, and asked us if we could help them with the starting system for the two Viper jet engines that power this beast.

The Longbow jet hydroplane world water speed record

We’ve donated a 4QD-300 to the cause and will be assisting in developing the circuits to get them turning and burning.

Kylie’s Wobbly Men

The guys at Pyrojunkies asked us if we could make the inflatable men used in Kylie’s latest tour a little more wobbly.

5 x Porter 10XXs got things sorted by turning down the fan speed.

Team Chicken at Lotus

We are proud to be sponsors of the Team Chicken guys! Congratulations on two brave 2nds at the Lotus event. Not only did they overcome some tricky technical issues but managed to drive through from the back of the field in the 2nd race. Oh and did I say that their car looks a million dollars!…

team chicken



















They again used their Porter 10XXX to great effect and were only just bested by a team running errrr…. another 10XXX.  


Pro-160 Coloured Covers

As a refugee from the mobile phone industry it was inevitable that we’d have to try coloured covers on our controllers at some point.

Here are some of the ideas we’ve been playing with on our Pro-160…..

We’ve 3D printed the brackets and used tough 3mm perspex as a wrap around case. The LCD can be seen through the cover for programming, or can be mounted remotely.

Please let us know if you like the idea.

Pro-160 update 3

Our Pro-160 passed an important milestone today [23/1/19] – the first installation in a loco!
Ian and the guys at the Aylesbury MES kindly allowed us to use their Deltic 2hp as a test mule. The new menu structure made it easy to tweak the ramps and limits and then off we went for a few laps. Everything worked exactly as intended and it barely got warm [due to the high performance mosfet drivers we’ve used].


Pro-160 update 2

Here it is, the first complete sample of our new Pro-160 😀  😀  😀  It’s a modular, relay free, full H-bridge progression from the Pro-150.

The testing is coming along nicely, we had it running happily at 100A today and the mosfets were only just starting to get warm. The main software elements are all working now, we just need to stitch them all together with the UI.


The headline features are:

  • Up to 250A and 84V depending on mosfets, capacitors, and heatsink fitted [water cooling will be available].
  • 2 x 16 digit display [can be remotely mounted].
  • Multiple control modes e.g. open loop, RPM, and current control.
  • Radio control input.
  • Inputs for
    • Deadmans handle
    • Emergency stop
    • Travel limits
    • Battery and motor temperature
  • Separate communications board.


Little Truckers – Scaled Rigs

I love the strap line that Scaled Rigs are using for their new mini truck!

This is the sort of project we love doing at 4QD. The truck has a very complete specification including lights and a startingly loud and realistic engine sound system. We designed the the full wiring loom which we’re sub-contracting out for them, and we also developed a new radio control servo emulator to allow the sound card to be driven directly from our DNO-5 controller. This needed a new PCB and software which we turned around inside 2 weeks.

The design and attention to detail that has gone into this product are mightily impressive, it is definitely not your average electric vehicle! If you’re short of Xmas present ideas for your nipper then you know who to call!

scaled rigs
















The DNO-5 is being slightly customised, and joint branded.


Greenpower Champions

Earlier this year Steve at Team Chicken asked us if we could do something to give them an edge in the Greenpower kitcar series. It took a lot of nagging on his part but we finally got our butt in gear and created the Porter 10XXX. Did it work I hear you ask? You bet, here they are en-route to winning the kitcar final at the weekend!

Greenpower champions

These guys are masters of marginal improvements, they’ve gone right back to basics and followed the Lotus maxim of “add lightness and simplicate”.

We’re chuffed to have been able to help.

Team Chicken now style themselves the Kitcar Final Champions [KFC], I suppose that’s just about better than the Vindaloo Victors, or the Madras Medalists, or the….


Electric car conversion

We’re always on the lookout for neat or alternative ways of doing things, and Les’s approach to electric car conversion meets both those criteria.

He’s taken a classic mini engine, thrown away the cylinder head and block, and grafted a Lynch 200 motor to the flywheel.

It’s going into a Magenta kit car, can’t wait to see how it turns out!

electric car conversion

Self propelled lighting tower

A long, hard day in the workshop saw us get the prototype drive system for this self propelled lighting tower up and running.

It’s got 2 x  48v 2.2kW Leeson motors which we’re driving using 2 of our Pro-150 controllers. These were configured for push button operation with variable speed.

It turned out to be a real beast – hugely torqey and easily capable of a brisk jogging speed. Our customer is targetting this at railway, highway, and runway maintenance operations.

self propelled lighting tower



Controller test board

For a while now we’ve been pondering how best to help customers diagnose problems with their controller installations. Our troubleshooting page and checklists have proved popular and effective but we still felt that something was missing. It’s a fact that well over half of all controllers that are sent back to us have nothing wrong with them. So to help track down wiring issues we’ve created this multi-purpose controller test board. It works by temporarily taking the place of the normal control wiring, and helps to identify and isolate problems.

Controller test board

It works with the 4QD, Porter, DNO, and Pro ranges.

It will be appearing in the accessories pages soon. We’ll be making one available free of charge to all model loco clubs [club reps please request yours by email].

Programmable Battery Meter

Here’s a pre-production prototype of our new programmable battery meter.

It’s very clever version of our old favourite 5 LED battery condition meter, only this one:

  • is much more accurate [+/- 0.1V]
  • has temperature compensation
  • has a low battery cut off function [can interface to most of our controllers to save those valuable LiPos]
  • can be programmed [by us] for almost any battery chemistry between 11V and 30V
  • will fit existing 5 LED BCM installations


programmable battery meter


Winning Greenpower F24 kit car

We like this overhead shot of 3 teams from the recent Greenpower Goodwood event. We’re particularly proud of the Team Chicken car from Bromsgrove School at the bottom of the frame, these guys kindly ran one of our prototype Porter 10XXX units, I’ll let them take up the story of how it went……

Winning Greenpower
Winning Greenpower F24 kit car with experimental Porter 10XXX


“Firstly, we were able to complete approximately another lap further than the xx.  And this then leads me onto the best factor we had from the xxx.  The tail off seemed to be much, much, much slower.  Before we would go strong, slow a little and then very slow for the last lap or so.  The xxx allowed us to keep pushing at a far faster pace with only losing a few seconds per lap (over a 2.4 mile Goodwood lap)  during the last few laps.  This then allowed us to gear up and get the Kitcar to an average 26.5MPH over a race.  Your controller did not heat up at all.  The only cooling we had on it was a computer heatsink with thermal paste.  We came first Kitcar by several laps, and 8th/11th  overall out of 100 teams (43 Kitcars).  It was so impressive that we are looking at gearing right up next season if tests continue to be successful.”


Pro-160 update

We’re getting a lot of interest in our Pro-160 that is in development so we thought we’d share some good news…..

It works!


Admittedly these are rev 1 boards, and the software still has a way to go but it makes a motor run forwards and backwards, and we’re seeing sensible current readings on the display.

A lot of effort has gone into getting the internal power supply able to operate between 12V and 100V which gives us the foundation for a very flexible range of controllers. We’ve also got a water cooled heatsink designed which will allow this baby to handle some big numbers.

The rev 2 gerbers are going to the factory next week so we’re expecting what should be sample ready hardware in May.

Nico has done a great job on the schematics and layout, now it’s over to Erica for some software magic.

New Battery Meter

Here’s a preview of our update to our BCM-524 battery meter. The old analogue model has been extremely popular and features in many designs. However battery technology marches on and we wanted something that would give more accurate results with lithium batteries and other types with flat discharge curves. We’ve used an ATtiny micro to produce a programmable replacement that can work with the small voltage changes these batteries give. Other features include temperature compensation, and a switchable output that can be used for a low voltage cut-off. Oh, and it still has the same hole spacings so it’s a direct physical replacement in most applications.

The first model will be suitable for 12V – 24V, we’ll produce some standard voltage curves for the common battery technologies, but if you want something custom please let us know.

Pronch’s PDQ Power Trike

Pronch Mulholland brought his PDQ power trike in for some TLC. We’ve now found a way to fit our Porter 5 into the existing control box making for a neat installation that retains most of the existing wiring. We’ve written up some quick notes on how we did it and included a wiring diagram.

pdq power trike

The supersize battery box is made from steel and houses 3 x 15AHr sealed lead acid batteries. It gives much better traction for hill starts as well as extending the range.


Our New Baby

Drum roll………. 4QD are pleased to introduce to the world our new baby – the SST-31.

It’s a small but perfectly formed, very clever, single direction controller for 12-35V and up to 30A.

It’s built around a Picaxe microcontroller, so as well as providing basic motor speed control, it can accept multiple control inputs and also has spare outputs for controlling ancillary equipment.

It’s ideal for the smaller motor control project, particularly those that need some element of customisation. We’ve made the software open source, and the Picaxe development system makes writing your own programs easy.

Pro-160 boards

An exciting day for us – we’ve just received the first PCBs for our new Pro-160 controller.

This is a modular, relay free progression from the Pro-150, headline features are

  • Up to 250A and 84V depending on mosfets, capacitors, and heatsink fitted.
  • 2 x 16 digit display.
  • Multiple control modes e.g. open loop, RPM, and current control.
  • Radio control input.
  • Separate communications board.
  • Loads of other features and control inputs.

Where’s my soldering iron? – lets get building!



One of the best things about running 4QD is seeing all the projects that our customers are involved in. This picture is from the Warsash Superyacht Academy and shows their fleet of training vessels. Featuring our Pro-120s and DNO-10s

Superyacht Academy training vessels,
Warsash Superyacht Academy training vessels. Using Pro-120s and DNO-10s

Electric Monster Truck

Is this a mini monster truck, or a monster mini truck?

Either way it’s a great piece of engineering and a totally new take on what to do when the kids say “Dad, can you build us a car please?”

A water cooled 4QD-300L is fitted to deal with the high currents that this beast needs.

Electric monster truck
Electric monster truck using a 4QD-300L


Here’s a sneak preview of our soon to be launched Softstart. This is a small motor controller stripped down to the basics that gives a progressive start-up ramp to eliminate the large torque spikes that occur if a motor is switched on instantly via a relay or switch. We’ve designed this using a small microprocessor which means that the ramp time is configurable, and also given it a couple of other inputs so that it can be used for a variety of other simple switching tasks. We’ll be making the code available to allow [encourage?] experimentation.

Renault Voiturette

Here’s a lovely rendition of an early Renault Voiturette that a customer has built. It’s using one of our Pro-150s driving a pair of electric scooter motors.

Renault Voiturette
Renault Voiturette with a Pro-150 driving 2 electric scooter motors

Electric Trials Bike

Here’s a prototype electric trials bike that a customer brought in today. Really powerful and very light, it’s using a Lynch motor and one of our 4QD-300s which we are modifying to give the required throttle response.

electric trials bike

Humvee Turret Drive

Here’s one of our Pro-150s driving the turret ring gear on a pretty serious looking Humvee. It’s a challenging application as it has to change direction rapidly, and the EMI and physical environments are hostile.

humvee turret

Water Cooled Dummy Load

Seeing as how we’d melted our air cooled test load, we knew that we needed something that could handle some really high currents. Here’s a quick video showing how we built a water cooled dummy load.

Steeple Cab Electric

This mighty machine has been built by Doug Wilkinson. It weighs in at 1200 lb and is using a 4QD-200.

Doug Wilkinson's Steeple Cab Electric. Using a 4QD-200, and weighing 1200lbs

Scarletts Ferrari

I’ve just got to share this clip of Scarletts Ferrari, it’s using one of our DNO-10s and looks absolutely stunning. I guess that’s what happens when your Dad restores cars for a living – not that I’m jealous – oh no!

Follow the links to see some of the other fantastic cars he’s made.



Steve W sent us this picture of his Robot Wars contestant Gyrobot. It’s using one of our Porter 10XXs to control what must surely be one of the most powerful rotating energy weapons we’ve seen so far. We’ve made some mods for him to allow the current limit to be adjusted, and he’s also trying out a prototype heatsink arrangement to cope with the rather unusual power profile.

gyrobot in robot wars

Panto magic

Mr B sent us this picture of a highly classified Xmas panto prop built out of a commercial scissor table with one of our Porter 10s driving a hydraulic pump.

panto magic

Oh not it’s not……

Cooling results

…and here they are…. the first results for our new range of cooling options for the 4QD-300.

cooling results

The finned air cooled heatsink gives approx 50% increase in performance and this can be increased further if a fan is fitted.

It’s the water cooling that we like the most though, it turns the 4QD-300 into a real powerhouse. More detailed results at higher currents to follow once we have uprated our test rig!

We’re still working out the pricing for these but please get in touch if you are interested.

Water Cooling

Here’s a picture of our embryonic test set up for the soon to be launched water cooled 4QD-300. On the left is our current air cooled load cell, ammeter, and data logger. Front right is the 4QD-300 fitted with the water cooled heatsink. Right rear is the control and pump for the water. We’ve left space for a second pump which will be needed when our water cooled load cell is ready. Can’t wait to run this lot and see what results we get.

water cooled
test rig for water cooled 4qd-300

Tow truck

Jeff Ivers sent us this picture of his tow truck that he uses to haul a gravity racer to the start line.

Fitted with one of our Pro-150s

Uprated 4QD-300

Here’s a sneak peak at our uprated 4QD-300X. We’ve had a custom heatsink made which really improves it’s ability to handle high currents for extended times. During testing it melted our test rig and was still only warm to the touch! Full details will be announced once we’ve built a new test rig.

The heatsink itself will also be available as an aftermarket upgrade.



We’ve also got a water cooled version coming soon that will take things even further, and be particularly suitable for electric boats.


PDQ Powertrike

Patsy brought a couple of PDQ Powertrikes to us with broken control boxes. We fitted one with a Porter 5, and one with a DNO-05 to see if we could get reverse, however we discovered that the motor has a one way clutch that prevents reverse from driving. The standard twist grips were swapped for our Magura throttles, and we fitted one of our key switches to the DNO for security.

WP_20160802_002DNO with key

















Two weeks later Patsy sent us this picture of the neat bag she made to tidy it all up

Patsys powertrike cover

And the verdict:….

"The power box is working briliantly, so speedy that I tend to do wheelies
unless I am careful. The battery is lasting longer too........
Thanks again for doing a great job on the trike."

Enduro bike

Chris Sharpe sent us these pictures of his enduro bike. It’s running a 4QD-300 controller, Lifepo4 batteries, and an Agni 95 motor.

Electric enduro bike with an agni motor Electric enduro bike

Product testing

Here’s Charlie having his first go at driving a loco. Thanks to Pete Ottley of Riverside Models for letting him try out his Class 37 at ndsme

Running a Pro-120 with switchable radio control / hand throttle.


A grand day out

A big thank you to the Electric Boat Association for inviting us along on their trip around St Ives / Earith.

Electric boats having a grand day out

In the foreground is Cedric Lynch’s remarkable electric canoe. It has no batteries [apart from a very small one to “get under bridges”], uses a small Lynch motor, a model aircraft propellor, and one of our old 1QD controllers. Goes jolly fast it does too!

Welcome to our new website!

We hope you like the new look. We’ve tried to make it easier to find the controller and accessories that you need, whilst still keeping all the interesting information and technical support articles in a new knowledge base that makes it easier to find what you’re looking for.

All of our controllers are now on the range page.

In our new knowledge base we’ve sorted all of our old articles into some clear categories. All of the information about our old controllers is there, and a lot of background information about motor speed controllers. Our sister site 4qdtec.com still has all the reference and circuit information.

We’ve also added some application areas that show just a few of the areas that 4QD controllers are being used in.

We’d like to say a big thank you to Adam from Cambridge web solutions for his excellent work in creating the new site.