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Guys

Yet another question for another one of my problems.

Sorry I seem to post alot of questions and problems and don't really post anything to help others. This is because I trying to learn this stuff and don't want to be giving people wrong advise.

My question is that I have a Tiny Trak SMT which is using the audio channel of my transmitter.

The tiny track works perfectly and transmitts the packet information and displays location on a moving map on my PC.

The problem is as soon as I connect the KX-121 camera to the video channel I get a good picture but the data stops transmitting.

I have used the transmitter in the past for transmitting Sound and picture and it worked O.K but I was using a pre amp on the audio channel at the time which I no longer have.

At the moment the Tiny Track is not using a pre amp.

The problem is only with the video signal being connected. The power to the camera does not effect the data on the audio channel.

Before I source and buy a pre-amp can anyone advise me if this may fix my problem.

Thanks

Crash Pilot1

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The problem is as soon as I connect the KX-121 camera to the video channel I get a good picture but the data stops transmitting.

As you listen to the audio channel (data) at the Rx, and then plug in the camera cables, what do YOU hear from the audio channel? Does the TinyTrak data tones go away, or are they merely a bit softer than before?

Also, does the supply voltage to the Tiny Trak decrease when the camera is installed?

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Mr.RC-Cam

You can still hear the tiny track transmitting when the video signal is connected but the signal is covered with a slight static noise. I have not checked the voltage but the tiny track is run directly of the flight battery which is a 2100 7.4 volt Li Po and the camera power comes of the same supply through a V Reg down to 5V. The TX is powered by the same supply also but through a DC-DC Step up switching Reg.

This test was done with the Plane receiver and electrics switched off.

I can run the camera with the electronics and electric motor running at any speed and I don't get any reduction in picture quality so even with the motor running I don't see any ripple effect.

Some of the information above may mean nothing in regards to this problem but it may give an idea of my setup.

I will have to check the voltage tonight when I get home and re carry out the tests that you have asked.

Thanks for your reply

Crash Pilot1

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The TinyTrak uses a 78L05 Vreg for its 5V supply. This part isn't fully compatible with 2-cell LiPO applications. The 7805 will give unreliable operation below 7V. You should plan on changing the Vreg to a LDO variety (perhaps an LM2931) once you get things working.

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Mr.RC-Cam

I bought a cheap pre-amp to test and installed it on the audio channel and it fixed the problem. Now it works perfectly but I have to find a surface mount pre-amp because I have no room left to install the standard pre-amp.

Thanks for the advise on the regulator.

Crash Pilot 1

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I think the pre-amp can be avoided. If this is truly a simple level issue then you should be able to change the resistor in the input of the TinyTrak to reduce audio attenuation.

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Mr.RC-Cam

Thanks for the idea. The tt smt has a variable resistor pot. I should have tried that first but didn't think of it.

I will try it tonight and see if i can adjust it to work without the pre-amp.

I want to try and prevent having to use a pre-amp because I have no room at all to install one.

Thanks for the advise and I will let you know how I go

Crash pilot1

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Adjusting its level pot is required on each installation. But if does not help then it may be necessary to change a resistor in the audio input's attenuator. If that becomes necessary, then post a schematic of the SMT board and we can help point out what to do.

There is a chance that the audio level is not the only concern. You mentioned that you heard static in the audio when the data problems occurred. That may mean that there is more to this than just a signal level issue. But, first things first.

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Mr.RC-Cam

Sorry for the late reply I have been doing some testing. I have been serching for a circuit diagram for the SMT but can't find one. They refer to the Tiny Trak 3 as being the same circuit but not in surface mount.

I am looking changing the TX with a Airwave module that I have put together but can't test it because I don't have the correct frequency receiver yet. Do you think by changing the TX that this may rectify or change my problem . I will post the circuit diagram for the Tinytrk 3.

Crash Pilot 1

wiring.pdf

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The audio attenuator is compose of 10K ohm POT R6 and 220K ohm resistor R5. I suggest you reduce R5 to 100K ohms and see if things improve.

This is can be done by adding a 200K to 220K ohm resistor ACROSS the existing R5 (leave R5 in place). Or, put a ~200K pot across R5 and tweak it until things work. Then replace with a fixed resistor.

I believe Yb2normal had to change R5 on his TinyTrak2 installation.

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I believe Yb2normal had to change R5 on his TinyTrak2 installation.

Yup... I actually ended up jumping the resistor entirely.

Then I was able to adjust the pot until the signal came through cleanly.

A really good tool is one of those 'audio oscilloscopes' that allows you to see the waveform as it is being received by your computer.

You can get a good sense if the received audio tone is too low or high or has too much distortion in it.

Regards,

Bill

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