Do Hornby Controllers make Locos Buzz?

[Chrissaf]

Yes, new Hornby controllers do buzz, it is because they use pulse width modulation (pwm) to generate a psuedo analogue voltage. It is the frequency of the pwm reacting with the coil in the motor. You should only really hear it at low speeds. I get it with old and new locos. It is a more efficient way to control a 12 volt motor. 

[walkingthedog]

I know DC controllers hum, my Gaugemaster version does, but I can't say I have heard a loco buzz. Never had that occur. Perhaps they do with Hornby controllers, does seem a bit odd. Gaugemaster use PWM. 

[Chrissaf]

If you are referring to the R7229 or R8250 then yes these controllers can cause some locos to buzz. And this is not the first time this 'buzz' issue has been raised in a thread, with the R7229 being particularly prone to exhibiting this behaviour based upon the posting history of this issue.

 

These controllers uses PWM (Pulse Width Modulation). PWM controllers have two output states. Full voltage output [12 volts DC] or zero voltage. The speed of the loco motor is controlled by switching this full voltage on and off very quickly in pulses. The width of the pulse is varied by the position of the speed control knob. When the pulse width is wide [control knob turned up], more power is sent to the motor and the motor turns faster. When the pulse width is narrow [control knob turned down], less power is sent to the motor and the motor turns more slowly, but because the narrow pulses are at the full 12 volts DC voltage, the torque the motor generates is high. It is this high torque at low speed that makes PWM technology motor control so popular.

 

Now, how many pulses are sent per second is the frequency.

 

High quality PWM controllers operate at a frequency that is at the upper end of the audible hearing range. But lower quality PWM controllers like the R7229 / R8250 operate at a much lower frequency well within the audible hearing range [probably because the cost to design and build a low frequency controller is much cheaper].

 

Now this lower frequency PWM frequency makes the locomotive motor shudder in pulses because of the pulsed nature of the controller output. But at the low audible frequency of the R7229 / R8250 design, it is this pulsed shuddering of the motor that you can hear as a buzz.

 

In general, with PWM controllers, the audible buzz is more evident when the loco is just starting to move and at snail pace speeds, but should lessen as the loco speed increases, due to the pulse width widening [shorter gaps between adjacent pulses, resulting in a pure constant 12 volts DC being achieved at controller maximum speed knob position].

 

In essence and in principle it is normal for, but somewhat undesirable in Hornby controllers. It is evidence of a cheap PWM controller design. Some loco motors seem to be more affected by this than others, thus it is a bit of a lottery.

 

There is not much you can do about it, barring investment in a much higher quality more expensive controller.

 

Edit: Others posted whilst I was preparing my reply, thus there is some overlapping (consensus) in my reply and theirs.

 

Note that WTD mentions that his Gaugemaster PWM controllers do not exhibit this behaviour. The GM controller range are considered as being high quality by many.

 

[Yelrow]

Hamment and Morgan ones, hum, also, Morley, also considered to be in top two, is silent.

[Ruffnut Thorston]

There are two things being commented on here.

 

The OP "problem" is that the locomotive buzzes when being run by the newer Hornby controller.

 

The title asks if the controller buzzes.

 

Most transformers can output an audible buzz. This is usually in the UK at the "mains" frequency of 50 Hertz. 50 cycles per second.

 

Older controllers tend to have the actual transformer, that lowers the voltage from 220-250 volts AC Mains to 12 volts, and via a rectifier, to DC, contained in the controller casing.

 

Hence the buzz comes from the controller.

 

More recent controllers tend to be powered from what is sometimes called a "Wall Wart", a transformer in a plastic case, with the mains three pin plug built in, with a connecting lead to the controller itself.

 

Any noise from the transformer will not come from the controller itself.

 

These plug in transformers often use different technology to the older transformer/controllers.

[walkingthedog]

I am a bit confused by the title. Is it the controller or loco that  buzzes?

[ColinB]

In the old days you used to get the mains frequency buzz if the controller contained a cheap transformer or passes a lot of current, walk past a substation Today's buzz is as I said before because of the pwm frequency they use. When I made my pwn controller years ago the locos used to sort of whistle because I used a much higher pwm frequency than Hornby use. This probably explains why you don't hear it from the gaugemaster controller, they use a higher frequency. All dcc controllers use pwm to control the motor, generally that is the only cost effective and efficient way for a digital system to control a motor, but you don't hear a buzz from them. As I said it all depends on the frequency of the pwm and how it reacts with the coil in the motor, to make a tuned circuit, which is why it makes the noise.

[atom3624]

Fascinating explanation from Chris - many thanks.

 

Al.

[Chrissaf]

Evening All,

I have searched for this one - but am not sure about the answer. I decided to get a new Hornby analogue controller and power unit - more as a back up for my existing one - which is from the late 1990's. Both arrived today from Hornby. Now setting the new controller up with its power unit (bear in mind it is not digital) I decided to check and make sure it works ok. 

SO here is the issue - when you turn the power up, the loco gives off a buzzing sound, as the power is increased the loco moves and the buzzing reduces. Now is that normal? reading other posts - it seems to be issues with old locos or a mixture of controller/ power unit, etc - but these is brand new.

And yes with my existing system - there is no noise.

Is this normal?

Keith

[Chrissaf]

Thread title edited to add clarity.

 

Thank you Al. I do try my best to implement the statement in my 'signature' panel.

 

@keihtp (Keith)

Just to add, you say your original controller is circa 1990's and doesn't cause locos to buzz. That is potentially up to 30 years ago. Hard to say without knowing the exact brand and model, but that controller is unlikely to be using PWM technology, as PWM is a much more recent technology in train controllers.

[atom3624]

In a way, it's similar to many / most (/ all?) microwaves with 'adjustable power' - you can hear when power is on and off ...  

 

Al.

[keithp1707821843]

Thread title edited to add clarity.

 

Thank you Al. I do try my best to implement the statement in my 'signature' panel.

 

@keihtp (Keith)

Just to add, you say your original controller is circa 1990's and doesn't cause locos to buzz. That is potentially up to 30 years ago. Hard to say without knowing the exact brand and model, but that controller is unlikely to be using PWM technology, as PWM is a much more recent technology in train controllers.

Thanks.

Yes the original controller is from 1995/6. No noise comes from it at all. I decided to buy a replacement - just in case - it is the R7229 and  a new power plug P9000. I wanted to stick with Hornby, in case of issues with  connections from other controllers. I do not solder but use the hornby clips.

It is a shame as the layout has shunting and so I run the locos at low speeds. Anyhow reading all the posts it would seem, that for this non digital set up, the buzzing sound is non-negotiable and I must put up with it. Lets hope my old controller last a big longer.

Thanks again.

Keith

[ColinB]

Sorry atom3624, the reason a microwave makes a noise is not because of pwm, I think you will find it is because of the fan, similarly on any computer the noise it makes is the cooling fan cutting in and out. 

[walkingthedog]

Keith my suggestion would be to buy a quality controller. Then you won't have to put up with unwanted noise and you will find control of the locos at any speed is perfect. 

[keithp1707821843]

Keith my suggestion would be to buy a quality controller. Then you won't have to put up with unwanted noise and you will find control of the locos at any speed is perfect. 

Ok - but dont they have to be soldered in place?

[walkingthedog]

No. Attach two wires to the controller and attach them to the track using any method you like. Solder is best but not the only way. 

[96RAF]

Keith my suggestion would be to buy a quality controller. Then you won't have to put up with unwanted noise and you will find control of the locos at any speed is perfect. 

Ok - but dont they have to be soldered in place?

 

No. You never have to solder to the controller end. They usually either have sprung or screw terminals. The wire between is normal twin core wire.

If you don’t like the slide in power clips then use a power track which has press and push in terminals. They make a half decent connection.

Controllers like R7229 are supplied with a twin pin connector that fits the track clip and power track. The same connector wire can be used with other make controllers.

[walkingthedog]

When I said solder is best I was referring to the track not the controller.  😆

[Ruffnut Thorston]

Interestingly, microwave ovens do consume more power in pulses.

 

They do not draw the same current continuously...

 

If you run a microwave oven from a generator, you can hear the generator responding to the higher power pulses....

 

[atom3624]

I do know the difference between power being applied, and an extraction fan!

 

It was a simple analogy.

I am talking about variable power settings on microwaves - the unit will apply a set power, but the duration per unit time will vary depending upon the power setting selected - loud hum ... fan only ... loud hum ... fan only - hence my comparison with the Chris explanation.

 

Similar idea, slowed down to the power modulation of the power supplies.

 

No need to go any further.

 

 

Al.

[keithp1707821843]

Keith my suggestion would be to buy a quality controller. Then you won't have to put up with unwanted noise and you will find control of the locos at any speed is perfect. 

Ok - but dont they have to be soldered in place?

 

No. You never have to solder to the controller end. They usually either have sprung or screw terminals. The wire between is normal twin core wire.

If you don’t like the slide in power clips then use a power track which has press and push in terminals. They make a half decent connection.

Controllers like R7229 are supplied with a twin pin connector that fits the track clip and power track. The same connector wire can be used with other make controllers.

So just to be sure I have got this, the current hornby track clip (R602) will also work with other controllers? Does that mean they have the two pins at the end of the wire?

[Yelrow]

The Hornby track clip, is the means of suppling power to the track, only. It will fit/ connect to any controllers, using the 2 wires.. I have mine connected to Hamment and Morgan, Morley, Guagemaster, and Hornby..

[Chrissaf]

....will also work with other controllers?

 

If they are Hornby controllers, as the Hornby controllers have used the same track connector for years and years. So all the Hornby train controllers are usually fitted with compatible wire terminations.

 

Any controller can in theory be used with the Hornby track power connectors. But note these comments.

 

It is easier to adapt the power tracks to other controllers rather than the power connectors because the power tracks typically have spring terminals for trapping the wires.

 

The power connectors can be used with other controllers if the bare wires from the other controllers are first terminated with a Hornby X8011 terminal pin. These pins are also designed to work with the power track spring clamp system.

 

At the end of the day, you just need to connect two wires to the two track rails. One just needs to use a bit of brain power and ingenuity to work out a method for oneself.

 

The method you finally adopt needs to be reliable in the long term. Personally, I prefer direct solder wire to rail solutions for maximum reliability. The Hornby track connection system [mainly the clips] do not in my opinion meet my high reliability criteria.

[Yelrow]

If you decide to upgrade your controller, look at Morley, where you get a Walkabout, as well. Very handy for controlling  , by being able to walk round to where your loco, derailed, putting it back on, and controlling from that point.

[Il Grifone]

Transformers should not buzz, but, in the real world, they often have loose laminations which vibrate and emit noise.

PWM, on the other hand, can cause the motor to buzz. If this occurs check that the motor does not overheat.

I have a Rivarossi N gauge B&O C16a 0-4-0 which is particularly allergic.