hk backlight mod

General mods that are considered worth doing; regardless of the end firmware you use.
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drcigg
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hk backlight mod

Post by drcigg » Tue Jan 17, 2012 5:31 pm

I thought I had read somewhere that after updating the firmware to er9x the hk backlight won't work without a mosfet soldered somewhere.

Also has anyone added a switch to turn the backlight on and off?
Does anyone have any info on this?
Pics and links to the parts needed would be greatly appreciated.


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Rob Thomson
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hk backlight mod

Post by Rob Thomson » Tue Jan 17, 2012 6:59 pm

Hello,

I believe you are after this.

http://code.google.com/p/er9x/wiki/CheapLED

Rob


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hk backlight mod

Post by cre8tiveleo » Tue Jan 17, 2012 7:20 pm

The hk led backlight always works. It's always on, to be able to turn it on and off you can add your own switch , potentiometer or the transistor mod from above link to turn it on/off with firmware.

:)


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Re: hk backlight mod

Post by drcigg » Tue Jan 17, 2012 7:32 pm

Thank you for the quick reply. This is all new to me so I am taking my time with these mods. Being able to turn off the back light within the firmware is good enough for me I don't need a switch then.

DeathWarmedUp
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Re: hk backlight mod

Post by DeathWarmedUp » Sat Jan 21, 2012 12:32 am

Hi Guys,

Firstly, fantastic work on the Mods/Firmware.

I have a question on this backlight Mod - can I use a 2N7000 instead of the BS170? Our local electronics store only has the 2N7000.

Thanks


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Re: hk backlight mod

Post by Rob Thomson » Sat Jan 21, 2012 8:06 am

Pretty certain it will work. It is just acting as a simple switch!
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Re: hk backlight mod

Post by jhsa » Sat Jan 21, 2012 8:14 am

I took my FET from an old servo. don't even know what it is.. but it works..
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

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Re: hk backlight mod

Post by B12 » Sat Jan 21, 2012 12:18 pm

rob.thomson wrote:Hello,

I believe you are after this.

http://code.google.com/p/er9x/wiki/CheapLED

Rob


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I think somebody should update/correct the wiki. The Backlight mod part is totally false information. The HK backlight draws much LESS current, not more than the EL panel. Plus the wiki makes you think the backlight does not work at all without soldering with er9x firmware.
Last edited by B12 on Thu Jan 26, 2012 12:30 pm, edited 1 time in total.

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hk backlight mod

Post by Rob Thomson » Sat Jan 21, 2012 12:23 pm

Pm me some suitable replacement text and I will amend it.


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Re: hk backlight mod

Post by Daedalus66 » Sun Jan 22, 2012 12:46 pm

B12 wrote:I think somebody should update/correct the wiki. The Backlight mod part is totally false information. The HK backlight draws much LESS current, not more than the EL panel.
The HobbyKing listing shows current draw as 60-90 mA, which is indeed far more than the EL panel. If this is wrong, say so in a constructive way and give your source. Wikis are all about contributing, not criticizing.

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Re: hk backlight mod

Post by ShowMaster » Sun Jan 22, 2012 3:20 pm

Daedalus66 wrote:
B12 wrote:I think somebody should update/correct the wiki. The Backlight mod part is totally false information. The HK backlight draws much LESS current, not more than the EL panel.
The HobbyKing listing shows current draw as 60-90 mA, which is indeed far more than the EL panel. If this is wrong, say so in a constructive way and give your source. Wikis are all about contributing, not criticizing.
I believe the current is being measured ar 10 Ma.
I have several new uninstalled bl i can measure.
So a question for anyone,
I think the bl is powered by a regulated 5 volt buss correct?
I never bothered to measure the source voltage so I want to be 100% correct for my test.
SM

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Re: hk backlight mod

Post by B12 » Sun Jan 22, 2012 4:48 pm

I have measured the current draw. The whole Turnigy 9x with ER9X draws 120mA backlight off and 135mA backlight on. This leaves 15mA for the light. This was with 9.5V battery voltage. The backlight has a 470 ohm current limiting resistor so the measurement is in line with ohms law.

Hobbyking claim of 60-90mA is 100% confirmed false information. Plus it is completely against Ohm's law by the way. There is no way you can push 60-90mA through a 470ohm reistor with ~10V battery. It is simply impossible. Led is the most effective way to create light these days. In this case you get twice the lumens with half the current compared to the EL light. If the HK light is too bright, just swap the resistor to 1K and you get similar illumination to the EL with 5-7mA current draw.

I have no confirmed information but I have a faint memory I have read somewhere the EL for 9X draws something like 30-40mA?

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Re: hk backlight mod

Post by B12 » Sun Jan 22, 2012 5:01 pm

Daedalus66 wrote:Wikis are all about contributing, not criticizing.
Problem with wiki's is they are sometimes based on opinion or even incorrect belief or false information. They are not confirmed fact unfortunately.

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Re: hk backlight mod

Post by MikeB » Sun Jan 22, 2012 5:16 pm

The difference in current consumption may be caused be a change in design. I have a graphic display from a different manufacturer that has a LED backlight. This is composed of 78 separate LEDs in an array covering the area to be illuminated. This backlight does consume a high current (100mA). I also have another backlight that is a rectangle of clear plastic with just 2 LEDs at 1 end. This consumes current in the 10 to 20mA range.

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Rob Thomson
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hk backlight mod

Post by Rob Thomson » Sun Jan 22, 2012 5:18 pm

B12 wrote:
Daedalus66 wrote:Wikis are all about contributing, not criticizing.
Problem with wiki's is they are sometimes based on opinion or even incorrect belief or false information. They are not confirmed fact unfortunately.
This is true. I think your original post came across rather negatively/critical. Joy of written text - it is not always interpreted how it is meant.

What may have been better to say was 'the wiki page is providing the correct info - can you update it to say x...y...z'. (and provide the new content)

The wiki pages have been pulled together by myself my scraping content from forum posts. They are far from complete - and certainly can do with checks for accuracy, typos and general errata. All of which takes time :(

I am not precious over what is written on them, so feel free to send me amends or content additions and I will update them accordingly.

Rob



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Re: hk backlight mod

Post by PNaz » Sun Jan 22, 2012 5:41 pm

Nice discussion on the problems of Wiki pages. This info should be added to the How To Guides page of the Wiki's so readers are aware that the topics are not the necessarily the perfect solutions and if they have had an issue and/or found a solution then let us all know.

Paul

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Re: hk backlight mod

Post by ShowMaster » Sun Jan 22, 2012 5:57 pm

MikeB wrote:The difference in current consumption may be caused be a change in design. I have a graphic display from a different manufacturer that has a LED backlight. This is composed of 78 separate LEDs in an array covering the area to be illuminated. This backlight does consume a high current (100mA). I also have another backlight that is a rectangle of clear plastic with just 2 LEDs at 1 end. This consumes current in the 10 to 20mA range.

Mike.
Yet to be measured again and finalized my best guess for the HK BL.
2 leds in series through a 470 ohm resistor to pin 3 of the 6 pin connector connected to battery + when on.
1.5v + 1.5v drop from 2 series leds= ~3v. Subtract that from battery, let's use 10v = 7v to drop with the 470 ohm series resistor in the HK BL = 7v/470 ohms = 14.89 Ma/ Hr draw. Using a 7.4 or 9.6 v battery even lower. 3 cell lipo, higher.
I have several uninstalled HK BL and will post current draw for good brightness from 5-12v first chance. So many post everywhere about the actual draw, 90 Ma on HK site, with 10-15Ma mentioned the most. It's time to get the facts and I'll do that but welcome anyone else to as well since we' all want to know no matter the source as long as it's measured, not guessed.
SM

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Re: hk backlight mod

Post by ShowMaster » Sun Jan 22, 2012 9:13 pm

HK White Backlight current draw vs. voltage applied 5-13V
The backlight has 2 leds wired in series.
5V = 5Ma
6V =7Ma
7V = 9Ma
7.4V = 9.8Ma
8V = 11Ma
9V = 13Ma
9.6V = 14.25Ma
10V = 15Ma
11V = 17Ma
12V = 19Ma
12.6V = 20Ma
13v = 21Ma
Brightness of the backlight does depend on TX battery voltage used. The brightness at 7.4V was more like the stock EL on the SP board. At 9.6V to 12.6V the brightness was much brighter. 12 volts was a little brighter than 9.6-10V but the current went up to 20Ma. I use a LiFe 9.6 volt HK battery so I’m going to use 14.25Ma as my final current constant .My metering of course may have some difference in accuracy but should be close enough for most.
For those using a 2 cell 7.4 type battery setup you may want to lower the 470 ohm resistor to allow the current to be 14Ma as the brightness increase is noticeable.
Hope this helps settle the current draw questions we all had.
SM
Last edited by ShowMaster on Mon Jan 23, 2012 6:30 am, edited 1 time in total.

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Re: hk backlight mod

Post by B12 » Mon Jan 23, 2012 5:55 am

Excellent job ShowMaster. I think this should be the correct Wiki material.

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Re: hk backlight mod

Post by ShowMaster » Mon Jan 23, 2012 6:43 am

B12 wrote:Excellent job ShowMaster. I think this should be the correct Wiki material.
Thanks, I'm glad to help.
I never was able to find this info with searches so now we have it.
From what I did find I'm certain that the other color leds draw the same current. Worse cases a few Ma. differant.
Showmaster

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Re: hk backlight mod

Post by GyroGearloose » Wed Jan 25, 2012 4:22 pm

I don't wish to restart the flamewar, and I'm ENTIRELY open to the idea that I just have a uniquely bad LED panel or strange radio or bad battery myself... but *on the exact same radio with the exact same LiFE battery*, I've found "real world" that if I normalize the battery life to a value of 1.0, I'm getting much LESS light and much LESS life out of the Blue HK LED panel. My LED panel is one of the earliest ones made by HK, and appears to have 1-2 LEDs, only one side of the clear panel.

Radio with no backlight on : 1.0
Radio with LED : 0.5 - subjective brightness "OK"
Radio with EL and Progammer : 0.9 - subjective brightness, "very nice"
Radio with LED and Progammer: 0.3 - subjective brightness "dimmer/OK"

Note that the LED had a "bad" drain by itself (I DO keep it on a physical switch now), and the smartie programmer combined with the LED seemed to have a special drain effect, worst of all. The EL barely made a difference in life (with my battery, I get hours and hours, so I totally don't care or notice UNLESS I'm actually timing the life on the bench).

I then got a 2nd radio when even ER9X couldn't handle all my models on one Tx... so I put the LED backlight in my 2nd Tx. Battery life is again about .5, and "OK" brightness just like before, so it's not the radio to blame. And now, just for comparison, here's BOTH radios on at the same time, same lighting, same charge state, for you to judge the brightness levels:
HK LED vs Smartie EL.jpg
-Gyro
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Re: hk backlight mod

Post by cre8tiveleo » Wed Jan 25, 2012 6:23 pm

Is there a short in the HK led connector?

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Re: hk backlight mod

Post by GyroGearloose » Wed Jan 25, 2012 7:12 pm

cr8tive_leo wrote:Is there a short in the HK led connector?
I had just that thought, but there didn't appear to be. I forget what the measured impedance was. Also, the picture I posted makes the HK LED look even dimmer than I'd consider it -- it's "acceptable" as a dull glow usable in the dark, certainly. Yes, dimmer than I expected when I got it, but not so bad I'd tear it out as worthless.

I've heard others complain they thought the Smartie EL panel wasn't very bright -- certainly not the case for mine! As shown, it *is* that much brighter, almost too bright for my wishes (left on, it affects my night vision enough to make the model harder to see at dusk). The super-bright EL may even have affected the camera's shutter, accounting for the HK LED looking SO dim.

-Gyro
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Re: hk backlight mod

Post by GyroGearloose » Wed Jan 25, 2012 8:10 pm

GyroGearloose wrote:I had just that thought, but there didn't appear to be. I forget what the measured impedance was.
Let's play math games...

If 1/2 of a 1500mah battery (750mah) is eaten in about 6 hours w/o the light, that's 125mah that the transmitter is drawing... I can get about 13 hours on a full charge, so this seems right on track linearly. Other's have suggested about 125mah for the Tx, so I'm confident of that number...

If ALL of a 1500mah battery is eaten in about 6-7 hours with the backlight on, that's almost perfectly double (214-250mah), suggesting the LED is drawing 91-125mah... I seem to remember HK had published that number themselves, and the math works out anyway you figure it. It's the same as the Tx when halving the life, and it calculates directly as well.

But yes, that does seem like a whopping high draw for 2 LEDs. Maybe by some strange method these LEDs draw more amps because they are running at lower voltage than normal (LEDs prefer to work at? But I thought loads usually draw fewer amps at lower volts? This is mostly speculation, though -- without being an electro-chemical engineer, all I can say is these LEDs suck for power vs. light. :-)

The Smartie board is an expensive way to get a programmer and light, but I can't complain about it WORKING as promised...

-Gyro

PS: Just to offer another possibility -- SM above was testing on a "White HK LED Backlight" -- mine is decidedly deep blue, not even aqua. I DO know that different color LEDs have very different lumination voltages and lumens/watts... maybe I just got the "lucky" bad color when I chose blue? The Smartie EL panel seems much "crisper" in addition to the brightness. If I recall correctly, the "backer" of the HK LED was a mottled silverish color, while the EL panel is a smooth bright white... that would make a difference when reading what is actually a clear LCD panel over the backlight. Even in the daytime without backlight, my HK-LED backed display looks "fuzzier." But again, for $5 vs. $40, the HK LED isn't bad as long as you run your Tx off of a car battery...
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Re: hk backlight mod

Post by B12 » Thu Jan 26, 2012 6:13 am

In the few posts above I mentioned the current draw of my BLUE HK led panel. The radio draws 120mA backlight off and 135mA backlight on so my backlight definitely draws 15mA with 9.5V HK li-fe battery. The light is bright for sure.

I have no idea what is going on with your light. It should have a 470 ohm resistor in line with the leds. Even if you short the leds, it cannot draw more than about 20mA with 10V battery. Are you trying to drive it with the smartieparts EL driver or have you connected it the original connectors ie wired directly to battery voltage?
Attachments
taustavalo.JPG
HK blue backlight with 9,5V Li-Fe battery. The black wedge below X was because the light was accidentally assembled slanted. Corrected afterwards.

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Re: hk backlight mod

Post by GyroGearloose » Thu Jan 26, 2012 2:16 pm

I don't recall seeing an obvious resistor in the wiring... but it's been a while since I stared at it. I got this when HK first offered them, so maybe HK "forgot" to put resistors into the first production run. My point in posting originally is that some people ARE seeing the ~90mah draw HK quotes. Maybe mine is doubly defective by being so dim even AFTER drawing so much current (although, looking at the HK site, their sales photo looks as bad contrast as mine).

At some point I'll reopen the case and swap my toggle switch for a transistor so ER9X can control the LED -- at that time, I'll double check there's a resistor NOW even if not before... :-)

-Gyro
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Re: hk backlight mod

Post by B12 » Thu Jan 26, 2012 4:56 pm

The resistor is under the black shrink tube and it is not visible without cutting the tube. If there is no resistor, the leds would be bright as hell the split second before they burn out. It is simply impossible for the light to draw more than 20mA. You just cannot feed more than that through the resistor even if yoy replace the leds with a solid wire.

What do you mean by the light looking "fuzzy"? Leds work by direct current and they make 100% stable light. They do not buzz or fuzz. Are you feeding them hight freq alternate current from Smartieparts board or did you connect them using the original connectors and following the HK instructions?

Whatever it is, there is something seriously wrong with your backlight. It definitely is not connected and/or working like it should.
Last edited by B12 on Thu Jan 26, 2012 5:18 pm, edited 1 time in total.

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Re: hk backlight mod

Post by ShowMaster » Thu Jan 26, 2012 5:13 pm

Hope this helps!
No guesswork, just the facts. :idea: :mrgreen:

HK White Backlight current draw vs. voltage applied 5-13V
The backlight has 2 leds wired in series.
TX battery voltage/current draw.
5V = 5Ma
6V =7Ma
7V = 9Ma
7.4V = 9.8Ma
8V = 11Ma
9V = 13Ma
9.6V = 14.25Ma
10V = 15Ma
11V = 17Ma
12V = 19Ma
12.6V = 20Ma
13v = 21Ma
Brightness of the backlight does depend on TX battery voltage used. The brightness at 7.4V was more like the stock EL on the SP board. At 9.6V to 12.6V the brightness was much brighter. !2 volts was a little brighter than 9.6-10V but the current went up to 20Ma. I use a LiFe 9.6 volt HK battery so I’m going to use 14.25Ma as my final current constant .My metering of course may have some difference in accuracy but should be close enough for most. 
For those using a 2 cell 7.4 type battery setup you may want to lower the 470 ohm resistor to allow the current to be 14Ma as the brightness increase is noticeable.
Hope this helps settle the current draw questions we all had.
If you install this BL note that w circuit board wiring error exists that stop the Trainer out/Simulator  PPM signal from working. It requires a circuit trace to be cut and a jumper to be added.  
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Re: hk backlight mod

Post by GyroGearloose » Thu Jan 26, 2012 6:29 pm

B12 wrote:The resistor is under the black shrink tube and it is not visible without cutting the tube.
Figured that...
B12 wrote:What do you mean by the light looking "fuzzy"?
The light is a steady glow, but the display itself looks fuzzier. This board downscaled my image or you could see what I mean better -- as it is, you can see at least a contrast issue. The EL has "crisp" text and the LED looks almost like there was a diffuser screen in front of the LCD display (no, there isn't one in FRONT, of course). What I think is happening is, because the LEDs shine sideways, the HK reflective backer is a sort of rear-diffuser -- it has to be "rough" in order to catch that light and bounce it forward, and multiple points are therefore catching the light and bouncing out at different angles past the LCD. Multiple light sources always create "fuzz" at the edges. I'll try to get a better picture if you still don't know quite what I mean optically.
B12 wrote:Leds work by direct current and they make 100% stable light. They do not buzz or fuzz. Are you feeding them hight freq alternate current from Smartieparts board or did you connect them using the original connectors and following the HK instructions?
I suppose a fair question to ask 3 times, but NO... I installed it just as told to using the included wiring harnesses. If you rewind, I found having the programmer and LED both installed was the worst drain of all, so after flashing the LED-equipped radio, I took out the programmer, which now lives on my 2nd radio with it's EL panel. Again, I don't have a programmer on the Tx that has the LED, so it's not powering the LED, nor RF-interfering with the LED.
B12 wrote:Whatever it is, there is something seriously wrong with your backlight. It definitely is not connected and/or working like it should.
People have said the LED is brighter than EL, and mine is certainly dimmer, so I'd second that diagnosis... :-)
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Re: hk backlight mod

Post by GyroGearloose » Thu Jan 26, 2012 6:53 pm

ShowMaster wrote:Hope this helps!
No guesswork, just the facts. :idea: :mrgreen:
Not really helpful, no. :-) I saw your posting before, and it's great to have "someones" data compared to the HK notoriously bad information. But, sadly, they're right in *MY* case...

Just to put this to rest, once and for all, I pulled out the ammeter and rigged up tap wires -- I get 121mah @ 9.80V for just the radio. Typical...
Switch on my LED backlight, and it spikes to 213mah, which suggests that *MY* LED panel is indeed drawing 92mah... sucks for me.

As I understand Ohms law, you're correct this is not possible with a resistor in the circuit, and yet it is... My LED doesn't burn out, it's just not very bright. So, how bout if they used a WRONG resistor? Too low would make it brighter, and two high would draw less current... So how bout if they soldered like incontinent monkeys, and there's a "partial" short somehow? I think if shorted across the led, you could divert enough power to dim the LED and raise the amperage... sound like a working theory? Either way, I just keep the stupid LED turned off when not in use, and don't worry so much about it... LOL... You all worry more about this than I do -- obviously, I use the EL and programmer radio more than this one. :-)

-Gyro
I could fly so much better if a second flight wasn't a requirement....


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