2nd look at the HK backlight mod, haptic mod and spker mod

kaos · Post by **kaos** » Sun Mar 03, 2013 5:41 am

well, long time ago I suspect one of my HK led light was bad: viewtopic.php?f=25&t=211&start=30#p2506
now I reopened the tx and surely the led is defective, either side the light is weak. I am going to order a new led from HK and put it in there with the 'back light mod' using transistor BS170.
I looked at the the light and the wiki, I just think using the bulky connector with the HK led is a waste. I looked into the board circuit in the wiki mod to the best I can, I come out with a way just to dump the bulk led connector. I am not sure I read the circuit correctly. I post it here to see if any one would point out this is not right. I think without that clunky connector is much easier without all those unnecessary wires and in between connector.
Basically just use the led and its two wires and add the BS170 and a 470 ohm resistor in a convenient place on main board.

Helle · Post by **Helle** » Sun Mar 03, 2013 8:46 am

Hy,

this connector is bullshid because there is only a 470 ohm Resistor in it,
and makes sometimes shorts and its so large.

I for me i use a 220 Ohm Resistor to 5V and the BS170 to switch

Helle

kaos · Post by **kaos** » Sun Mar 03, 2013 5:39 pm

do you have a pic of where you put them?
the point I am pointing at is a 5V line right?
if you use a 200 ohm resistor the led must be brighter than the stock 470. I never know what the HK led is made of (voltage, 2 in parallel or in series), but obviously 220 ohm works. I should use a 220 as well then. It would be brighter.

I also wonder if this will work: http://www.ebay.com/itm/400275309100?ss ... 1438.l2649

its cheap, 300V , may be good for something else in the future.

gohsthb · Post by **gohsthb** » Sun Mar 03, 2013 8:53 pm

The third pin from the right on that connector is the switched battery voltage. the resistor there will depend on what battery you are using (voltage) and how the HK back light is wired. I would start with the 470 resistor. If the light isn't bright enough then try a smaller resistor. Also the color of the backlight will make a difference too. Different colored LEDs drop different voltages.
-Gohst

kaos · Post by **kaos** » Sun Mar 03, 2013 11:01 pm

ah, that is what that line is. I am using 2S lipo or 3S life so it will be from 7v (2S lipo runs to minimum) to 10.8 v (3S liFe fully charged).
so if we use that line, the brightness will decrease when batt runs down?

the transistor from ebay can work just like the BS170 right? if so I will order it, I am waiting for the new HK LED, it is over the pacific now.

do you have a suggestion for a 5V line? I figure if it is from a constant voltage would be better.

kaos · Post by **kaos** » Mon Mar 04, 2013 12:40 am

here is the second question. spker/haptic mod. I have the little compnoents in hand now. 1k, 300 resistor 10 uF cap, 1N4001 diode and a pancake vibrator. the only thing I don't have is the 4.7 uF capacitor for the spker. Can I use a 10 uF capacitor for it? also I have looked at the spker/piezo mod over, but seems to be lost with what kind of spker can be used. one point says piezo is needed, but later it appears to me that any small real spker will do as well. is this correct?
I have a couple those free disposable head phone from the airline company from previous flight, will that spker good enough. I tore it apart but there is no marking of any kind as for what kind of spker or ohm is. can I use that as the spker?

Post by **jhsa** » Mon Mar 04, 2013 1:16 am

what do you measure with the multimeter when you try to read ohms?? I mean the airplane headphones.. Some of them might even be piezo??

10uF instead of the 4,7uF in this case should be fine. Don't drive a magnetic speaker specially if it has low impedance directly from the processor pin. It will need some circuit with a transistor..

kaos · Post by **kaos** » Mon Mar 04, 2013 2:06 am

It is about 40-50 ohm. have no clue what kind of sper it is. here is a pic:

Post by **jhsa** » Mon Mar 04, 2013 2:26 am

it's magnetic.. even if is 40 or 50 ohm I don't know if it is safe to drive it directly from the processor pin.. I wouldn't..

kaos · Post by **kaos** » Mon Mar 04, 2013 2:27 am

so I need a 5-8 ohm spker?

Post by **jhsa** » Mon Mar 04, 2013 2:37 am

For that mod I would use a piezo speaker

kaos · Post by **kaos** » Mon Mar 04, 2013 2:51 am

yep probably the $2.34 piezo as mbanzi listed on his wiki would be good. you are sure the 10uf cap would work too? I got ten 10 uF cap from ebay for the frysky current sensor project. i may search around a little to see if I can find a piezo some where in the junk electronic i have in the house.

may be I will use that airline spker for the 'voice' mod when time comes.

Post by **jhsa** » Mon Mar 04, 2013 3:04 am

if that capacitor is in series with the speaker, then yes, you can use it.. it is a polarized capacitor I guess, so connect the positive of the cap to the processor side. The same as per mbanzi instructions..

Just checked.. follow mbanzi's guide..

João

kaos · Post by **kaos** » Mon Mar 04, 2013 3:52 am

jhsa wrote:if that capacitor is in series with the speaker, then yes, you can use it..

it means the 10 uF cap, not the spker right?

kaos · Post by **kaos** » Mon Mar 04, 2013 4:00 am

Helle wrote:Hy,

this connector is bullshid because there is only a 470 ohm Resistor in it,
and makes sometimes shorts and its so large.

I for me i use a 220 Ohm Resistor to 5V and the BS170 to switch

Helle

yep, just used the led calculator to back track from a 470 ohm 8.9 v (stock battery) to 5V, the resistor is 220 ohm.

which 5V point you use on the main board that won't destabilize any thing?

Post by **jhsa** » Mon Mar 04, 2013 1:46 pm

kaos wrote:
jhsa wrote:if that capacitor is in series with the speaker, then yes, you can use it..
it means the 10 uF cap, not the spker right?

Right. The cap. I wouldn't use that speaker directly to the processor pin..

João

kaos · Post by **kaos** » Mon Mar 04, 2013 6:00 pm

quick question. due to the availability of piezo spker, while I am waiting, can I just put the spker and haptic mod in without attaching the piezo spker and leave the stock buzzer for now and use the buzzer. once I get the piezo spker, can I just attach the spker without removing the buzzer at that time? I will put a connector in there, then just plug in the spker later.
since now I have everything except the spker, and have some time in the next couple days.

gohsthb · Post by **gohsthb** » Mon Mar 04, 2013 6:39 pm

The buzzer is a piezo element. It won't be as good as the piezo speaker, but you can connect it like the speaker would be for now. I suspect it will be quieter and the tone will be way off. But all you need for now is that it makes noises.
-Gohst

kaos · Post by **kaos** » Mon Mar 04, 2013 6:44 pm

then later when I get the piezo spker i can just attach to connector without removing the stock buzzer? or it will reduce the out put of the spker? I am planning on leaving a two wire connector for spker for now. later just plug in the spker at the connecter

gohsthb · Post by **gohsthb** » Mon Mar 04, 2013 8:09 pm

Take the buzzer off, I don't know but it will probably interfere in some way. For now just reconnect it where the speaker should go.
-Gohst

kaos · Post by **kaos** » Mon Mar 04, 2013 8:48 pm

will do, I will just make a two wire connector to the buzzer, then when I get the piezo just plug in the connector.

thx.

kaos · Post by **kaos** » Tue Mar 05, 2013 7:54 am

well, on the way home stop by radio shack got a piezo spker

. The one mbanzi used is not in stock so i pick up this one:
http://www.radioshack.com/product/index ... cale=en_US
and here is what happened:

Now just need to wait my programer and LED to come in to finish it up.

I found I have some of these in the drawer, ordered by mistake while doing the DSMX mod. was going to have 3.3 V but end up with this. so might as well put them into use. : http://www.ebay.com/itm/330588241078?ss ... 1438.l2649
I think I am going to hook this up to the +V line in the 1st post pic and run the led from this and also my neon tx on/off light too.

kaos · Post by **kaos** » Tue Mar 05, 2013 10:58 pm

Can I use this to turn on/of the Hk led light? http://www.radioshack.com/product/index ... cale=en_US
no local shop near me has BS170 or any listed in wiki.

if this works, I might as well get it from radioshack instead of waiting for Chinese shipping. My HK led should be here soon.

gohsthb · Post by **gohsthb** » Tue Mar 05, 2013 11:38 pm

Here is a link to the part datasheet.
The 2 parameters that you are interested in are Drain to Source voltage, and drain current. This device is 60V and 200mA. It should work fine in this application.
-Gohst

kaos · Post by **kaos** » Tue Mar 05, 2013 11:44 pm

thx gohsthb. dan it is easier to type ghost.

I did not know higher v and a would work or not. looks like i can get this thing done once I get the programer and HK led in.

gohsthb · Post by **gohsthb** » Wed Mar 06, 2013 12:13 am

You could use a 1000V 100A FET! It would probably wouldn't be cheaper, but it would work. Might have to check the gate trigger voltage on one of those too. Depends on the FET.
-Gohst

kaos · Post by **kaos** » Wed Mar 06, 2013 12:59 am

here is the stat sheet. what am i supposed to look for with this type of thing - gate trigger voltage?
http://www.nteinc.com/specs/400to499/pdf/nte491.pdf

gohsthb · Post by **gohsthb** » Wed Mar 06, 2013 1:10 am

Gate Threshold Voltage

kaos · Post by **kaos** » Fri Mar 08, 2013 2:46 am

well, unfortunately, raioshack only has the nte941 by mail , no tin local shop. so I picked up a 2N3904 from the local shop: http://www.fairchildsemi.com/ds/2N/2N3904.pdf

seems to me this one should work as well. lower speced but should do it?
and just as a afirmation, the E should go to the gnd on the board, B goes to pin 17, and C goes to the LED. correct?

gohsthb · Post by **gohsthb** » Fri Mar 08, 2013 3:45 am

Put a 1k resistor from pin 17 to the base. Should be fine.
-Gohst

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2nd look at the HK backlight mod, haptic mod and spker mod

2nd look at the HK backlight mod, haptic mod and spker mod

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