Powering IR receiver (v1) with 5V

[Bartosz]

Just wanted to check whether someone has already tried it. I haven't yet got connectors to try it out (with my power bank), but I plan to conduct such tests.

My scenario would be IR receiver powering train motor(which works fine with 5V).

[Toastie]

@Bartosz

works like a charm. Even 4.5 V work - I am powering 4.5 V trains /w original motor and battery car with the PF IR receiver. 5 V for sure, at 4.5 V it sometimes misses a signal.

Best
Thorsten   

[Bartosz]

3 hours ago, Toastie said:

@Bartosz

works like a charm. Even 4.5 V work - I am powering 4.5 V trains /w original motor and battery car with the PF IR receiver. 5 V for sure, at 4.5 V it sometimes misses a signal.

Best
Thorsten   

Cool! Not sure I understand your setup though, as you've mentioned you're powering 4.5 trains with this receiver. Just to be clear - what I mentioned is replacing battery box (9V) with 5V power source. 

[Toastie]

Hi Bartosz,

I am powering the PF IR receiver with the 4.5 V provided by the 4.5V train battery car (3 x AA batteries in there) using a "custom cable" (which is nothing more than two 4.5V plugs wired to the 9V/0V PF terminals (the two outer wires, check polarity). The PF receiver then powers the 4.5V train motor with another custom cable.

There should be no problem in supplying 5V to the PF receiver, which then powers a 9V train motor. Naturally, you don't get the same torque/speed from the 9V train motor as compared to a 9V powered PF IR receiver. There is more info over at TrainTech. Or just PM me.

All the best and good luck with your project!

Thorsten

[Bartosz]

@Toastie Thanks! 

It seems like only my planned voltage regulator might be the weak part in the chain - under load (depending on input voltage), their efficiency varies, and voltage may drop below desired level and I just probably need to conduct that test to see if its enough :)

Great to see so many tinkerer here:)

 

Hmm, just one more thing @Toastie - those 3 AAs, are those rechargeable? (this would make it even less than 4.5v) 

Edited April 15, 2018 by Bartosz
One more question

[Toastie]

Hmmm.

This is a little weird: A voltage regulator is designed to regulate. What is the input voltage min/max? With plain vanilla regulators such as 7805 you should always have 2 ... 3 V above the 5V. But there are low drop voltage regulators as you may know (e.g. L4945, which works reliably with 6V input voltage).

No. These are 1.5V batteries. I don't believe 3.6 V will work.

Best
Thorsten 

[Bartosz]

8 hours ago, Toastie said:

Hmmm.

This is a little weird: A voltage regulator is designed to regulate. What is the input voltage min/max? With plain vanilla regulators such as 7805 you should always have 2 ... 3 V above the 5V. But there are low drop voltage regulators as you may know (e.g. L4945, which works reliably with 6V input voltage).

Right, but I was talking about step-up (boosting) regulator such as: https://www.pololu.com/product/2564

There you see that for Vin 2.4V, at 450mA output current, there is 80% efficiency. There are no more measures after that, but they also mention:

 

"If the input current exceeds the switch current limit (typically somewhere between 1.2 and 1.5 A), the output voltage will begin to drop".

 

So yeah - that's what probably been puzzling you, as I've phrased it like it is just dropping voltage, whereas I was only concerned with situations where we could be close to that maximum input current.

Checking Philo's measurements,  with his load (no idea how much it weight though), this motor consumes 360mA, which should be somewhere at 85% efficiency,  so if I'm not horribly mistaken it would give around 850mA input current,  so still below 1.2A.

To summarize, I think that under heavy load (also when stalled), it could not be able to provide enough voltage for IR receiver to operate.

Thanks for listening to my ramblings!

 

Edited April 16, 2018 by Bartosz

[mocbuild101]

6 hours ago, Toastie said:

I don't believe 3.6 V will work.

I'm pretty sure it will, I've powered it with a 3.7v LiPo - it's not much use (due to under-powered motors), but it works...

I've also had success powering it with a Lego solar panel - the IR reception is bad, but it's still green...