Pololu stepdown

[Saleem]

Am using dftc fc so no 12v reg,so wantvto run a tx thst takes 7-24v.didnt click on but used a 12v-12v pololu and was running 4s batteries and had it connected to the esc rail,today i broke the pololu as i didnt tealise it was taking 14.8v battery,its actualy shiwing 15.1-15.3ish on the esc rail when i meter it.

My question is,what voltage reg is best and where should i realy attach it,or perhaps use a 5v-12v stepup,can i do that,use a stepup on the5v reg esc rail,is that feasable and work.makes sense as the 5v wont fluctuate whereas the esc rail might go skatty when braking and cornering?

Looked at this:
http://www.ebay.co.uk/itm/192038067139

But before i pull trigger,am i best buying a stepup,5v-12v?

[Powernumpty]

I';d get another drop down, it doesn';t make sense to boost the voltage from 5V, the current required from the 5V will be higher than from the battery down, more chance of brown outs on the 5v rail.

I';ve tried a few generic BEC';s and they have been better than I expected.

Not actually tried this version but they often just use the same IC and few trimming discrete resistors/caps so should work the same.

http://www.banggood.com/Diatone-Mini-2A-BEC-V2_0-Version-3_3V-5V-12V-For-RC-Multirotors-p-1032859.html?rmmds=search

[Saleem]

After much reading it would seem that the reg i used takes from 4v-18v and outputs 12v,so its a stepup and stepdown.

I cant confirm but cos i already supplied 15.1v to the esc rail i attached it to i can only assume i was pulling in excess of 18v so went over the allowed input voltage.

I have bought the same pololu again and this time i will attach it to a regulated 5v point on the dtfc,more likely the esc rail as it will only ever output 5v and wont spike,so i can use the pololu as a stepup.

That makes sense?

[Cheredanine]

Hi mate, so there are a lot of pololu s but they pretty damn good, what one were using? Because of damping light/active breaking you can get power spikes but never had an issue with the 12v or 5v step downs that hobbyrc sell, you do need to link the shutdown pin the the battery pin though to stop them shutting down

[Saleem]

http://www.ebay.co.uk/itm/192038066678?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I had a crash when i went flying at lunch time,then i got no more pic,i came home and trouble shot the quad and metred the output and it read 0.so assumed it was fried out.i bought another but i still got this one here,i didnt realise they are stepup and stepdown.

Whats this shutdown cos i looked and can see shdn on the pololu.

I will have a google meanwhile.

Thanks.

[Saleem]

Ok,so this pololu is same as one i linked,i had crash,no pic on goggles,came home,trouble shotband no output voltage on pololu.

Shdn was not bridged,i did home work now to bypass shdn and to bridge shdn and vin,done the bridge but still no output like the pololu is permanently fried orbstill in shutdown state,so question is,how to activate the pololu if its shut down?

[Cheredanine]

Hi mate,
So pololu have been around for ages and are brilliant regs, I use hem all the time if the pdb doesn';t have a built in reg

If you look at the bottom of the board, the four pin holes have labels, on one side (depends which way round you have he board) the edge pin hole is labelled shdn or something like that, that is the shutdown pin, next to it is the Vin pin where you feed it the battery power

The shutdown pin can be used to shot down the reg if the source voltage is iffy on clever electronics but for quadcopters, the shutdown should be connected to the vin pin.

Note the one you link is a step up/down with an input range of 2.5-18v
If you are using a 4s power supply you would be better using a step down, the part number I would look for is D24V6F12
That will rated up to 24v and I use it on most of my 4s rigs with nasty powered motors that spike way up, never had an issue

[Fletch]

i use these
http://www.ebay.co.uk/itm/1-2-5-pcs-MP1584-Adjustable-3A-DC-DC-Converter-Step-Down-Voltage-Regulator-UK-/281847500556

If your that way inclined ... a reg test by the grumpy old man
https://www.youtube.com/watch?v=J3hoK-XL27Q

[Cheredanine]

i use these
http://www.ebay.co.uk/itm/1-2-5-pcs-MP1584-Adjustable-3A-DC-DC-Converter-Step-Down-Voltage-Regulator-UK-/281847500556

If your that way inclined ... a reg test by the grumpy old man
https://www.youtube.com/watch?v=J3hoK-XL27Q

:) other regs are available, although that is a switched reg, it is gonna produce more noise, not the best for fpv kit

[Fletch]

You should maybe watch the video then ....

[Powernumpty]

The Polulu he';s using is switched (AFAIK can';t have step up voltage without some switching) and as Fletch linked in RCModel Reviews tests the Polulu was actually noisier than the other D-Sun tested. I thought of that video when I linked to the Banggood item.
But then as also said there so many Polulu items some may be excellent.

I';m not sure if I got the link to those step downs from you Fletch but I';ve used them all over the place (non RC mostly, admitted) and had really good results so for the wide range input and few pence cost (was about £4 for ten when i got some) I';d certainly try more based on the same chip.

[Cheredanine]

You should maybe watch the video then ....

I figured I am enough of a grumpy old man without bothering Bruce about everything

The best approach for fpv is to use a linear reg, as powernumpty said all the regs we have pointed out are switched regs.

If there are issues with a switched reg dropping an LC filter in should sort

[Saleem]

i use these
http://www.ebay.co.uk/itm/1-2-5-pcs-MP1584-Adjustable-3A-DC-DC-Converter-Step-Down-Voltage-Regulator-UK-/281847500556

If your that way inclined ... a reg test by the grumpy old man
https://www.youtube.com/watch?v=J3hoK-XL27Q

If i bought this reg how would i set the output to 12v as it seems its not fixed output?or am i missing something?

Thanks.

I am willing to try something different every now and then.
::)

[Cheredanine]

The cpvarriabke output Ines have a dial, on that it is to the left of the board, looks like a small crosshead screwdriver is needed, you plug a multimeter into the output and plug the power in and turn the dial until you get the output you want

[Saleem]

Your a wealth of knowledge cherads!

[Cheredanine]

Maybe but my predictive text kills me every time