Power a layout with a laptop charger?

[William-835226]

Hello everyone,

My transformer recently died (it was quite old) and I found out that the charger for my laptop fits the controller. Do you think that it would supply enough power for a simple oval track and an 0-4-0 as a temporary solution? (even if i was to run on the controller's 'low' setting?)

I'm not good on voltage and amperage so I'm asking here

Thanks

[Chrissaf]

There are two vital bits of information you haven't given us.

Firstly - which Hornby controller by R model number.

Secondly - what does the label on the laptop PSU say i.e specifically output voltage and what current is available. The label may quote Voltage and Watts and not current, but the current can be worked out from the Watts value for a given Voltage.

Most laptop PSUs are DC output, whereas some Hornby controllers [older ones] require an AC input.

Most laptop PSU's do not really have a standardised output voltage. Usually, laptop PSUs can be about 19 volts DC or so which could be too high for some DC powered controllers.

Therefore nobody can give you a definitive answer unless you answer the two questions asked above.

[William-835226]

Hi, thanks for the reply,

My controller is a R7229 and my laptop charger is rated for 19 volts and 2.37 amps.

[Chrissaf]

The Hornby R7229 controller uses the Hornby P9000 PSU. This PSU is rated at 19 volts DC at 0.5 amps with centre pin being positive voltage. Your laptop PSU is also rated at 19 volts DC centre pin polarity unknown but most PSU standardise on centre pin positive. Thus from purely a voltage point of view it is compatible. The fact that your laptop PSU is rated at 2.37 amps is not a significant issue as the controller and the trains it powers will only draw as much current as they need. But be aware, that in a 'short circuit' scenario, the laptop PSU will be able to supply nearly five times more current to the R7229 controller than the R7229 is designed for. So there is a risk of permanent damage to the controller in a 'short circuit' scenario.

[William-835226]

Thank you very much you've been very helpful.

[JJ73]

Hiya

You can do what Chris says above for a temporary / short term solution but for a permanent / long term solution check out my Controller review & see what you think...

Thank you 🙂🚂🚂🚂

[Rana Temporia]

Build your own PWM controller using that power supply. You can get the complete circuit off the internet for less than £3 from China if you are prepared to wait and don’t want to build your own, which would probably cost more. I have now built several (and given some away) and have no intention of going back to standard 12v controllers. The circuits are usually rated up to 24v and have a cut-out built in.

Do a search on here for an explanation of how they work.

[M. Matthews]

Years ago as a kid, I had the opposite problem... Laptop charger broke so I found my old Hornby power supply and plugged it in as it fit...

There was about 5 seconds of a buzzing noise from the laptop, a pop and then smoke. Killed the laptop dead.

[Gordonvale]

But be aware, that in a 'short circuit' scenario, the laptop PSU will be able to supply nearly five times more current to the R7229 controller than the R7229 is designed for. So there is a risk of permanent damage to the controller in a 'short circuit' scenario.

 

 

Resistors and fuses will prevent this.

[ColinB]

Generally a laptop charger should work, I use them for powering Leds in my kitchen and the lighting for my railway. There are two things you have to worry about. First is the output from the charger too high and secondly is it too low. Generally most controllers have an AC filtering stage where they filter the "nasty s" from the power supply so as long as your charger's voltage is not too high then no issue. I had this same issue with my Fleishmann controller, which is obsolete so no spares, in the end I just tried it and it worked.

[96RAF]

As already explained you are initially looking at voltage and supply amperage, and as Colin says the quality of the output can affect your controller performance. The reason the Hornby power supplies are so expensive I am told is because they use high quality circuitry design for the task, that has been certified and that certification costs them a lot of money. Each significant design change to say a module like the HM6000 means recertification at recurring cost.

A branded laptop supply will have been similarly certified against its prime use, but those cheap and cheerful power supplies from China may or may not be of such quality or have been anywhere near a certification facility regardless of what any labelling on them states.

[Jimbo1707820979]

Pardon my hijacking this thread. Much has been said about "the easiest way to strip gears is by changing direction without stopping the loco". But has anyone had actual experience of this ? Or is it another urban myth ?

Moderator’s Note: Jimbo your highjack question is totally unrelated to this topic, so I suggest you raise the question as a new post in the General Section, before anyone answers it, then can you please delete this post yourself using the three vertical dots context menu at the right hand side. Thank you.

[ColinB]

The Hornby power supplies will be CE rated, that is why you find with a lot of devices that there is a separate power supply. We were thinking of selling one of our internal designs at work, it quickly became very apparent that to have the power supply separate made getting CE certification a lot easier. A good quality laptop supply will be CE certified, so if you stick to these you should be ok.