Voltage input and output on 9v train regulator

[toxicbananna]

Hi Guys,

I wanted to increase the voltage output for my 9v layout thus I bought an adapter which rated 20v 2amp, plugged it in and crank it to the maximum and noticed the output from the regulator is still at 9v.

Questions for the electronics gurus,

1. Is there a safety feature on the Lego 9v regulator which disallow more than 9 volts output?

2. Is there any way of modifying the regulator to allow me to output as per my adapter ratings?

Cheers guys!

[Richfilth]

The Lego regulator takes in AC voltage and outputs DC - check the power supply for more details.

The circuitry inside the regulator is extremely simple and yes, it will only output 9V. Why do you want more? I think 20V will potentially kill a lego motor.

[kieran]

also its a liner regulator that is inside. so if the vMax out is 9V and the input is 20 the regulator has to dump the 11V depending on the current that is pulled through this will cause it to heat up more quickly and the thermal shut-down will kick in limiting the current. 12V will be a safe bet and if you look at the back of the regulator near where the power plug jack is you will see the 9-12V ~ written. it will not hurt the motors as the voltage will not get through unless the chip in side gives up in a bad way

[legoman666]

If you want your trains to have more oomph, you need to get rid of the Lego 9v regulator and use something that can output more current than 300mA. Could always double up 2 Lego regulators if you don't want to delve in to model train stuff

[AlmightyArjen]

You could also use an old 12V lego train transformer to give your trains some more juice. But I really wonder why you want to do that since on 9V the trains run already pretty fast. Next to that: long time on a voltage higher than 9V will make the motor wear out much sooner...

[bonox]

The Lego regulator takes in AC voltage and outputs DC - check the power supply for more details.

it is capable of taking a DC input as well, and they're generally much easier to find these days.

If you have your heart set on it, try a general HO or similar style power controller. You should be able to find plenty of 12V units. According to philo, the 9V (and PF motors for that matter) will run happily at 12V with considerable speed boost, with unknown change to their life.

eg

http://www.hobbiesplus.com.au/electrical.htm

or grow your own

http://home.iprimus.com.au/nuggles58/Making%20A%20Basic%20DC%20Controller.pdf

[toxicbananna]

The Lego regulator takes in AC voltage and outputs DC - check the power supply for more details.

The circuitry inside the regulator is extremely simple and yes, it will only output 9V. Why do you want more? I think 20V will potentially kill a lego motor.

I do know that using 20v to run my motor will kill it eventually. I'll not pump to my layout at 20v all the way, just only on some section of my track layout..

also its a liner regulator that is inside. so if the vMax out is 9V and the input is 20 the regulator has to dump the 11V depending on the current that is pulled through this will cause it to heat up more quickly and the thermal shut-down will kick in limiting the current. 12V will be a safe bet and if you look at the back of the regulator near where the power plug jack is you will see the 9-12V ~ written. it will not hurt the motors as the voltage will not get through unless the chip in side gives up in a bad way

Do you happen to have the circuity of the regulator so that I could change the chip to increase my output of 20v?

You could also use an old 12V lego train transformer to give your trains some more juice. But I really wonder why you want to do that since on 9V the trains run already pretty fast. Next to that: long time on a voltage higher than 9V will make the motor wear out much sooner...

I do know that 9v train are pretty fast on the full turn, just that i have a couple of long straights which would like to increase it speed. I do not have a 12v lego transformer, does the output of the transformer similar to the 9v ones?

it is capable of taking a DC input as well, and they're generally much easier to find these days.

If you have your heart set on it, try a general HO or similar style power controller. You should be able to find plenty of 12V units. According to philo, the 9V (and PF motors for that matter) will run happily at 12V with considerable speed boost, with unknown change to their life.

eg

http://www.hobbiespl.../electrical.htm

or grow your own

http://home.iprimus.... Controller.pdf

Thanks for the info, I would like to use the original 9v controller rather than after market controllers.

[bonox]

Thanks for the info, I would like to use the original 9v controller rather than after market controllers.

in that case, it uses an LM317 linear regulator.

https://en.wikipedia.org/wiki/LM317

The variable input to the regulator is provided by voltage drop over fixed value resistors from the reference value. You'll need to change the regulator chip for a higher Vout model and may also need to adjust the 7 resistors to suit. I'd suggest starting with the chip and see what the result is before hacking the board apart too much.

Edited March 22, 2015 by bonox

[zephyr1934]

I do know that using 20v to run my motor will kill it eventually. I'll not pump to my layout at 20v all the way, just only on some section of my track layout..

...

I do know that 9v train are pretty fast on the full turn, just that i have a couple of long straights which would like to increase it speed. I do not have a 12v lego transformer, does the output of the transformer similar to the 9v ones?

Ah, maybe you do not need a more powerful transformer at all, maybe you are running into too much resistance from the rail joints, combined with high current, limiting the amount of power getting to the motor.

Try moving the track power connection to the middle of one of these long straight sections (only temporarily, so it is okay to use an extension cord to move the transformer over to that general area. Do the trains perform a lot better now on that stretch? If so, you just need to add more power connections to the track from your existing controller.

[DanSto]

You can also assemble power supplies in series to get 18 or even 27 V using additionnal rails

as shown in this video where the train has two motors running under 18 V :

[Brickthus]

Here is the circuit for the 9V train controller.

To increase the voltage, reduce the value of R2. The voltage and speed settings will stay in proportion across a wider range.

I recommend less than 10 Volts as the maximum output for LEGO motors, unless you intend to power a 12V motor.

This would need R2 to be about 423 ohms, which would need a 3900 ohm resistor in parallel with R2 (currently 470 ohms).

However, the best thing to do has already been mentioned - beef up the current to more than 300mA.

The way to do this is to replace the LM317 in the TO-220 package with an LM337, which comes in a TO-3 package.

You may also need a heatsink to dissipate the heat from more current at the standard voltage drop of 2 Volts across the regulator.

It has been done successfully up to 5 Amps before. This may be in a very old post somewhere.

I have used a dual 30V 3 Amp power supply on the main lines. This provides the smooth power that the 9V motors prefer.

I am careful not to exceed 9 Volts. A railway show usually needs only 7-8 volts for an express train in a larger scale.

Another way would be to drive the track power feed from a Power Functions LiPo battery box with a PF extension lead.

The PF battery box produces PWM so there is more torque at low speed settings for a better pull-away from the station.

It also gives up to 800mA so it will handle 2-3 motors with ease (assuming a 6-wide train).

I exceeded 800mA with larger trains (4 train motors + 2 gearmotors + 3 lights, needing a total of 1300mA), causing the battery box to attempt to restart the train on the uphill section.

You might find that the 9V motors don't like PWM (and buzz their disapproval) in which case a smoothing capacitor may help.

Mark

[Lazarus]

I would recommend going to the older 12v controlers, they have 18v and 8amps. both AC and DC outputs.

One of these controlers can run 4 9v motors at one given time on my layout.