Powering PF receiver from aother PF receiver ouptut

[Zerobricks]

Just wanted to say, you can power PF receiver from another PF receiver output, and the motor on that ouput will work normally! What do you guys think, can this be usefull?

[backbone]

Just wanted to say, you can power PF receiver from another PF receiver output, and the motor on that ouput will work normally! What do you guys think, can this be usefull?

Works, useful. And this idea was discovered by makorol couple of months ago.

Original topic in polish:

http://www.lugpol.pl/forum/viewtopic.php?t=8909

[Milan]

I used this idea as soon as I got 8275 two years ago. It works as (expensive) cable extension.

[Mortymore]

... It works as (expensive) cable extension.

I agree. Thought I never did any experimentation, just looking to the schematic of the 8884, you can see that an 8884 receiver only gets the regular power from the outer lines of the cable, and inner control lines are not connected. If they were somehow, then it would be possible that you could activate the second receiver, only when the first one enabled it. But the receivers pass the input voltage directly to the outputs, through the outer lines, and that's why that cascading receivers is nothing more than an "expensive cable extension", as Milan called it.

Cumps

[SuperCow]

The only way to use remote on remote it to change the cable see improvised schema.

Normal the outer powerlines are used, the inner is used for the motor, as it can reverse polarity.

With a small change you can use it to power the remote

The only negative I can think with this system is as C1 and C2 can deliver total 1000 milliamp of power.

So XL motor's are out of the question.

As in the other topic, a switch can be used as well:

Then you can use a motor with remote to control the switch, and not have the 1000milliamp problem

Edited September 5, 2010 by SuperCow

[Mortymore]

Lets observe the 1st schematic, since C1 and C2 works as reference (0v) of the other when one has 9v, I see that it would only be possible to power the 2 secondary receivers alternatively, i.e., when the upper one is powered because C1 has 9v to the GND reference, then C2 has to have 0v, meaning, the same as the GND reference, and so the lower receiver is not powered at that moment. If the inner lines of the primary receiver where switched, by a reverse command, then C1 goes to 0v, and C2 to 9v, powering the lower secondary receiver, and shutting down the upper one.

Hope I made myself clear.

I don't know also if that's what you are expecting to achieve.

Cumps

Edited September 5, 2010 by Mortymore

[Burf2000]

Why would you do this?

Also why cant you run a pf reciver off a 9volt old battery pack. Randomly if you plug it in an output slot it works for a minute or so

[Toastie]

Lets observe the 1st schematic, since C1 and C2 works as reference (0v) of the other when one has 9v, I see that it would only be possible to power the 2 secondary receivers alternatively, i.e., when the upper one is powered because C1 has 9v to the GND reference, then C2 has to have 0v, meaning, the same as the GND reference, and so the lower receiver is not powered at that moment. If the inner lines of the primary receiver where switched, by a reverse command, then C1 goes to 0v, and C2 to 9v, powering the lower secondary receiver, and shutting down the upper one.

Hope I made myself clear.

I don't know also if that's what you are expecting to achieve.

Cumps

That is true, if you go with the current remotes (either the "bang bang" #8885 or the #8879 set at full speed fwd or bwd).

If you'd use the NXT brick (somebody asked what to do with it ...) along with a HiTechnic IRLink, you can control the setting of the pins individually. If you'd "set" both (+) then they are both working. At first sight this is a somewhat expensive approach. On the other hand (I am a train head ...) you can control PF 8 motors using one base address. That would be good for 8 switch points and still leave you still with free channels for trains.

Regards,

Thorsten

Why would you do this?

You could extend the address range available to you. Lets assume you want to run each motor at a time: Set receiver with "base adress 1" on pin A/C1 to (+); set slave receiver 1 output A with on address "2" to fwd. Only receivers powered up (= belonging to the "address 1" A/C1) will react.

What would that be good for? Well see the other post - one eample would be if you want to run a bunch on remotely controlled switch points (PF motor driven) on large train layouts remote controlled AND run PF trains, you are rather short on "adresses".

Also why cant you run a pf reciver off a 9volt old battery pack. Randomly if you plug it in an output slot it works for a minute or so

Hmm. That would require the PF/9V conversion/extension cable, right? Did it really work for a minute and under load?

Regards,

Thorsten

[Burf2000]

Thanks for your reply mate, really useful. My robot is nearly using all channels (plus 2 nxt's) so very useful info

The 9v to pf cable did not work, I guess there a second feed for a ir receiver and you just cant power off old battery boxes which is a shame

I was trying to run pf of a train controller as it would save having a rechargeable box