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Member postings for Phil Green

Here is a list of all the postings Phil Green has made in our forums. Click on a thread name to jump to the thread.

Thread: LED wiring
09/08/2020 17:26:20

You're right C8, if someone asks a question its really not worth the trouble of answering it.... wink

No-one reads the replies anyway... for example I'd posted the typical Vf of various coloured leds...  laugh


Edited By Phil Green on 09/08/2020 19:11:41

09/08/2020 14:55:49
Posted by gangster on 09/08/2020 14:50:37:

what am I overlooking please?

I think its this bit:

Posted by Phil Green on 09/08/2020 14:16:21

Whats not visibly apparent is that cell one is powering 4 leds, cell two is powering 2 leds and cell three is powering 1 led.  How do you propose to keep the cells balanced?  


Edited By Phil Green on 09/08/2020 17:30:26

09/08/2020 14:16:21
Posted by Zflyer on 09/08/2020 13:54:49:

I have connected the LED's to the balance connector on a 3s lipo as per my diagram.

Some you just can't help wink

Posted by Zflyer on 09/08/2020 13:54:49:

All working with no apparent problems.

Whats not visibly apparent is that cell one is powering 4 leds, cell two is powering 2 leds and cell three is powering 1 led.  How do you propose to keep the cells balanced?   
You asked a question, several people took the time to competently answer, its your choice to ignore them all, but I wonder - why ask in the first place?  smiley

Your diagram as posted:



Edited By Phil Green on 09/08/2020 14:52:46

Thread: Electro mechanical retracts control board
08/08/2020 21:09:14

You can do it much simpler than that and for much lower cost.

It looks like a simple DC motor driving a lead-screw with limit switches. Almost everything you need is already there. All you need is to be able to apply DC power in one direction (polarity) to raise them and the other polarity to lower them. The top diagram shows a simple switched reversing supply, the switch could be driven by a servo.

The lower diagram shows the wiring of the limit switches. With the power in one polarity it will drive one way until the limit switch breaks. With the power reversed it will drive the other way until the other limit switch breaks. The diodes allow the return current through the 'open' switch.  Arrange the motor terminals so it drives towards the appropriate limit switch, ie with pos on the left drives it towards the limit switch on the right and v.v.

Your only other job is to adjust the limit switch positions if necessary.








Edited By Phil Green on 09/08/2020 09:54:23

Thread: LED wiring
08/08/2020 20:45:16

So these leds have inbuilt resistors, presumably they are the 5v ones.   So you can in theory put one or more parallel leds across a single cell, NOT like your diagram but one (or a parallel bunch) between red & yellow, one (or another parallel bunch) between yellow and green, and one (or yet another parallel bunch) between green and black. However if they are different colours or different numbers in the bunches they will draw different amounts of current and your lipo would be pulled out of balance by the different loads on each cell.   So this would work but its a very bad idea.

With the components you have there you could run them all in parallel from the 5v BEC (or receiver battery) or you could run two similar bunches in series from the outer balance connections, ie from full battery voltage.  You would need to match the bunches pretty well to ensure both halves each saw about half the pack voltage.

Either way would preserve cell balance.

Taking your drawing as posted, the answer to your original question is no, you have some across one cell, some across two and some across 3 cells, so the ones on the left of your diagram are connected to 12.6v and 8.4v, and the ones on the right to 4.2v ....  so each led or parallel bunch sees a different voltage.
You say "Phil, the leds are wired to separate cells via the balance led" (lead?) but thats not what you've drawn smiley 
All your current-limited leds need to see roughly the same voltage though some variation wont hurt, it doesnt need to be exact, a 5v resistive led is happy with say 3.5 to 7v or so, the '5v' spec is conservative for long life.

The crucial point that you didnt mention is that you have leds with a built-in resistor.  Otherwise the forward voltage of a non-resistive LED is between 1.8 and 3.3 volts depending on the colour, unless they're high-power ones like Crees. Reds are about 1.7 to 2.0 volts, blues 3 to 3.3 volts, with yellows and greens inbetween. If you connect unprotected leds directly to a low impedance source of 4.2v (ie a lipo cell) without current limiting resistors, they will blow. The ones on the left of your diagram connected to 8.4v and 12.6v will blow spectacularly! 
This is irrelevant however since you do have resistive leds smiley




Edited By Phil Green on 09/08/2020 12:36:46

08/08/2020 15:49:45

Not sure what you mean by "The LED's are set to cell voltage" ?   LEDs have a fixed forward voltage and need some method of controlling current, either resistively or with PWM.   

Your arrangement will pull the Lipo out of balance, you have two leds running from one cell, another running from two cells, and another running from 3 cells. 

I would put all 4 in series across the whole pack, this would maintain balance, ensure they all get the same current, and waste less power in the current limiter.

To answer properly we need to know exactly what you're planning & what components you've used.



Edited By Phil Green on 08/08/2020 17:52:28

Thread: Old School Glider Power Pod Part 2
04/08/2020 21:12:05

I think you're right Cliff, but I'd made it before I realised. If I slide it right to the T/E its about level smiley

Thread: FCC proposes $2.8m fine against Hobbyking for marketing non-compliant drone transmitters
04/08/2020 18:25:47
Posted by HobbyKing August 2020:

you will surely have heard about the insane US2.8 Million dollar fine announced by the FCC for a handful of naughty products we stopped selling years ago...

Thats strange HK, I bought some of them from you only this year!

Thread: Old School Glider Power Pod Part 2
04/08/2020 18:13:53

My Impala power-pod is smaller and much less aesthetic but I've made it independent,
having no connecting wires. It has its own dedicated throttle receiver, ESC and battery
and so can be rubber-banded to almost anything:







Edited By Phil Green on 04/08/2020 18:16:59

Thread: WD40
02/08/2020 12:46:26

Any serious Jimi Hendrix fans will know of the British band, the Hamsters a fantastic live band, sadly retired.

Throughout a gig their guitarist Slim would spray WD40 down the length of his guitar neck every three or four numbers. Didnt wipe it off, he just played it 'wet' smiley

Thread: Any surviving Ardente D1001 etc transformers out there please?
01/08/2020 14:21:14

This is a really, really long shot... the Ardente D1001 etc matching transformers featured in almost every 1960s receiver project, by chance does anyone have any in their stash please?
Ta v much smiley

Thread: Arduino programming for beginners.
01/08/2020 14:17:35


31/07/2020 23:58:18

I could post examples, some responders are downright rude, arrogant and dismissive but reading between the lines I gather that you're 'politely aware' of that Bob. As a well established enthusiast (and a microelectronics teacher) I found their treatment of beginners (some only kids) was appalling and so I avoid it - unless its improved over the last few years.


29/07/2020 23:36:02
Posted by Bob Burton on 29/07/2020 14:13:42:

Plenty of help available on the Arduino forum of which I am a moderator (UKHeliBob) is quite the least friendly forum I have ever used. In fact I'd go further than that, a lot of responders are aggressively dismissive. Pick any topic at random and you'll see. Really discouraging for beginners who at best get an 'RTFM' and are dismissed as an inconvenience.


Thread: LiFe Nomenclature
18/07/2020 23:58:40

Yes, LiFe is an abbreviation, lithium & iron dont chemically bond without the phosphate, its a valency thing smiley
You do have to be careful when speaking verbally about Lithium-ion and Lithium Iron, 
so its best to give LiFePo4 its full title.




Edited By Phil Green on 19/07/2020 21:35:53

Thread: RDS.what is it?
18/07/2020 18:30:11

This has an amusing side - single-channellers have been using 'RDS' in the form of torque-rods since the dawn of time. The original 1967 S/C Veron Impala plan showed the very linkage referred to in the RCG thread - an angled shaft rotating in a sleeve within the control surface:


Thread: Fly aways
18/07/2020 10:09:25

My one and only flyaway was a free-flight KK Dolphin glider, I'd just finished it, lovely job, and decided its maiden should be off one of our club slopes. Took it to one of our Sunday slope sessions at Highlow and launched it off the slope. It slowly tracked into wind, climbing and climbing - absolutely perfect - and climbing and climbing.... never to be seen again.

A couple of years ago at the Ponty Single Channel & Retro R/C event, several minutes into the Blunderbird-Racing slot I realised that for some time I'd been watching the wrong model... mine had safely landed itself 200m away.


Edited By Chris Bott - Moderator on 18/07/2020 22:17:51

Thread: Help! Can't charge my Lipo
10/07/2020 00:35:16

Some charger menus specify peak voltage, not nominal, so the settings for a 3S lipo are 4.2 and 12.6v.
Maybe yours does - your cells are over 3.7 presently, hence you charger gives the cell voltage error. The 3.7 setting would be the peak voltage for LiFePo4 chemistry.

So maybe you've told the charger to expect a LiFePo4 but connected a LiPo.



Edited By Phil Green on 12/07/2020 00:37:34

09/07/2020 23:49:58

Silly question, you do have the power connector plugged in as well as the balance plug?

Also, on your charger, you said that you'd set the volts per cell to 3.7v.

Just check that there isnt a 4.2v setting, and 12.6 for the pack.

If so, those are the correct settings.

Edited By Phil Green on 10/07/2020 00:04:25

Thread: FRSKY Failsafe.
09/07/2020 18:19:43

It literally means the receiver doesnt send any servo PWM pulses when in failsafe John. Without pulses an ESC will stop, and servos will stay in their current positions but with no holding resistance to movement, just like when they're unpowered.  'No pulses' is often used by flight controllers etc to detect failsafe as it doesnt waste a channel.




Edited By Phil Green on 09/07/2020 18:24:05

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