PF -> 12v motor, safe limit for IR receiver

[roamingstop]

I have a few older 12v motors which I'm thinking of running via a custom PF cable. In principle this is not a problem - assuming PWM at 9v then it means the 12v motor will never reach it's maximum RPM.

However I'm wondering what would be the effect of supplying the IR receiver with a higher voltage (say 11v lipo).

1. Does the IR receiver still limit the maximum PWM output to 9v?

2. Is the IR receiver likely to blow or have a shorter lifetime at these slightly higher voltages?

Note all my IR receivers are the v1 type - I know that v2 would allow more power to be drawn from the batteries - and hence might handle 12v motors better. But since I don't expect to power two 12v motors from one battery pack I'm not too worried

Thanks for any hints or tips

[JopieK]

Probably Philipe knows this. I think it will be cut down though by LEGO, they make a lot of there stuff very tamper proof. So I think you would be safe, but I hope the voltage convertor for the PF receiver logic will not heat up too much.

[hoeij]

I read on the technic forum that the IR receiver does work with 11v. Just make sure to get the polarity right!

[kieran]

PWM chops the full voltage into small chunks, its then the average of these chunks that gives rise to the perceived voltage at the motor and hence its speed. assuming the PF receive done not clip the voltage it will supply all of this voltage for 100% or 50% of time depending on the speed setting of the receiver. It has been tested a few times with higher voltages and it seems to be fine.

[le60head]

From my experience the v1 IR Receiver can handle 12 volts. I do know if it is safe, but it works.

I have modded a PF Battery box to run on a DC power supply instead of batteries. It is currently powered by a 12v DC 1250 miliamper transformer.

I used this to power the 8043 Motorized Excavator. All the 4 motors, which are connected to the 2 v.1 IR Receivers spin noticeably faster and have significantly more power then when they run on 9 volts.

I hope this answers your questions. Still, i doubt it is recommend to power the PF system with 12 volts instead of 9.

[Philo]

I wouldn't indeed recommend to overvoltage the IR receivers. Even though it seems to work fine at first, lifespan of receiver could be reduced... For example V1 receiver motor driver (LB1836M) has a 10.5V absolute maximum rating! V2 driver gives a bit more leeway at 11.8 AMR. And we know nothing of IR receiver controller chip (LEGO custom) or surrounding capacitors.

[LongLEGOUser]

Not to bring an old horse back from the dead, but do we know the absolute max of amps that the IR receiver can take?

I have seen that 1 amp for 9 volt is said to be the max but at 12 volts what is one looking at for that voltage?

I am trying to run a computer supply that supplies 12 VDC but at 14 amps....

Hold on be fore we freak out though...

I have a dc to dc step down convertor to adjust for a large track layout which the step down is set at the 12 VDC INPUT to 9 VDC on the OUTPUT for the train pick up.

Supposedly the dc to dc step down will only use the amps needed to power whatever is on the receiving end, so if it needs only one amp then that is all that gets through...

Any thoughts on the mention above?

Thanks in advance guys!!!!

Edited April 22, 2014 by LongLEGOUser

[kieran]

The motor will only draw what it needs, so if it needs 1A it will draw 1A from the supply, if the supply is rated at 14A all this means is that in theory a load could draw this current. so if you had 12 motors all drawing 1A the total load on the supply would be approx. 12A leaving you 2A of head room. Does this help?

[1974]

I run my 12V motors from a 9V batterybox through the old RC system (I've taken the electronics out of the large trainbases)

Works well, drives fast enough for me. I only have a 7727 type and small diesel shunter, but it's a joy to watch the rods move on those oldie red motors