Audio Video Battery question.

[(*steve*)]

a zip file of a recording of the noise

Very interesting. A whistle starts when the monitor is powered on, and there is a periodic sound when the camera is recording -- so 2 different noises. Maybe there's a bit of hiss when you turn on the video out too.

Is this what you hear?

I would try replacing the 12V switchmode regulator with a linear regulator, but I'm not sure that would be a trivial thing for you to do.

I'm wondering if there is insufficient input voltage and it's misbehaving somehow. The outputs are variable. If the monitor still operates at say, 10.5V, wind the switchmode regulator to 10.5V and see if the whistle is reduced, or changes pitch.

davenn points out that the outputs seem to be mislabelled. Can you tell us what the actual output voltages are for each device, both with the device turned off and again when turned on. e.g. 5D output = 7.25 V with camera off, 7.18V with camera on and recording.

 

[jeep642]

Very interesting. A whistle starts when the monitor is powered on, and there is a periodic sound when the camera is recording -- so 2 different noises. Maybe there's a bit of hiss when you turn on the video out too.

Is this what you hear?

I would try replacing the 12V switchmode regulator with a linear regulator, but I'm not sure that would be a trivial thing for you to do.

I'm wondering if there is insufficient input voltage and it's misbehaving somehow. The outputs are variable. If the monitor still operates at say, 10.5V, wind the switchmode regulator to 10.5V and see if the whistle is reduced, or changes pitch.

davenn points out that the outputs seem to be mislabelled. Can you tell us what the actual output voltages are for each device, both with the device turned off and again when turned on. e.g. 5D output = 7.25 V with camera off, 7.18V with camera on and recording.

You could say it's two different noises but they come from the same problem. When you turn on the camera you can hear it sort of boot, then the monitor and when it's on and idle the noise stabilizes. When the camera is recording there's a little orange led that blinks on the camera; it's blinking is in sync with that periodic noise. So basically the noise is a manifestation of what the devices are doing and likely of how much power they're drawing I suppose.

Would you point me to a 12v linear regulator?

I'll try lowering the voltage out of the regulator and see if there's any changes.

Yes, there's a typo on the schematic. The regulators are set to output 12v for the monitor, 9v for the preamp and 7.2v for the camera.

I will also test if the voltage varies when you turn on and off some of the devices.

The battery gives AT LEAST 14.4v when half charged (above 15v fully charged). I assume this is sufficient to get 12v out of a regulator...

 

[(*steve*)]

Would you point me to a 12v linear regulator?

What current is required by the monitor?

The battery gives AT LEAST 14.4v when half charged (above 15v fully charged). I assume this is sufficient to get 12v out of a regulator...

2.4V *may* be enough. If you can wind the voltage down a little that will give it a little more headroom. If that makes a significant change to the noise, then we may be onto *a* cause.

 

[jeep642]

What current is required by the monitor?

Well, I wired it from where you can mount a battery. Officially 12v but it could handle the 14-16v of the Anton Bauer directly without problem.

2.4V *may* be enough. If you can wind the voltage down a little that will give it a little more headroom. If that makes a significant change to the noise, then we may be onto *a* cause.

I tried that. Monitoring the voltage going in the preamp as I lowered the voltage going into the camera from 7.2 to 6.20ish until the camera died and monitoring the voltage going in the camera as I lowered the voltage going into the preamp. No change in the noise whatsoever.

Although I noticed a few things. If I only connect the monitor and the preamp, the noise is actually a steady, high pitched, not too loud whine AND a lower one at the same time.
Connecting the camera and the preamp gives a noise much louder, lower frequency and there's a cycle in it.
BUT if I connect the preamp the monitor and the camera (but do not power it) I only get the high pitched one. If I disconnect the power supply of the camera I get the lower noise back.
So basically connecting the power supply of the camera without powering the camera removes some of the noise generated by the monitor. If this makes any sense.

 

[(*steve*)]

Well, I wired it from where you can mount a battery. Officially 12v but it could handle the 14-16v of the Anton Bauer directly without problem.

OK, I asked about the current, but it seems that you have connected it without a regulator without problems.

You don't say, but I presume it made no difference whatsoever to the noise.

I tried that. Monitoring the voltage going in the preamp as I lowered the voltage going into the camera from 7.2 to 6.20ish until the camera died and monitoring the voltage going in the camera as I lowered the voltage going into the preamp. No change in the noise whatsoever.

OK

Although I noticed a few things. If I only connect the monitor and the preamp, the noise is actually a steady, high pitched, not too loud whine AND a lower one at the same time.
Connecting the camera and the preamp gives a noise much louder, lower frequency and there's a cycle in it.
BUT if I connect the preamp the monitor and the camera (but do not power it) I only get the high pitched one. If I disconnect the power supply of the camera I get the lower noise back.
So basically connecting the power supply of the camera without powering the camera removes some of the noise generated by the monitor.

Interesting...

If this makes any sense.

Not immediately

Let me think more about it give some of the others a chance to read this. Maybe they'll see something obvious I've missed.

I'm pretty sure it is noise from the regulators, perhaps exacerbated by the grounding issues.

 

[jeep642]

Just trying to revive this thread with an idea.

Since after month of research it seems that no solution arised. Here's another suggestion:

Given that the problem comes from the preamp being connected to the same power source as the camera, monitor, etc... I need to find a way to power the preamp with this same main battery without the preamp being connected to it...

Would this be doable?:

A system with two 9v rechargeable batteries to power the preamp.
One 9v battery would power the preamp while the other 9v battery would be being charged by the main battery and when the one powering the preamp falls under a given voltage, the system switches to the other 9v battery while the first one is being charged.
(The "switch" is barely noticeable in the audio. I tried with a "manual" switch)

If any of you guys had any idea on how to put something like this together, it would be greatly appreciated!

Thanks!

 

[jeep642]

BUMP

Anybody?

 

[jeep642]

Anybody has any idea on how to do this by any chance?

Just trying to revive this thread with an idea.

Since after month of research it seems that no solution arised. Here's another suggestion:

Given that the problem comes from the preamp being connected to the same power source as the camera, monitor, etc... I need to find a way to power the preamp with this same main battery without the preamp being connected to it...

Would this be doable?:

A system with two 9v rechargeable batteries to power the preamp.
One 9v battery would power the preamp while the other 9v battery would be being charged by the main battery and when the one powering the preamp falls under a given voltage, the system switches to the other 9v battery while the first one is being charged.
(The "switch" is barely noticeable in the audio. I tried with a "manual" switch)

If any of you guys had any idea on how to put something like this together, it would be greatly appreciated!

Thanks!

 

[(*steve*)]

OK, my suggestion is to replace the regulator you're using for the pre-amp with a liner regulator. Get a 7809. The pin-out is very similar to the modules you're using now.

You should place a capacitor across the input and output of this regulator. I would use a 470uF 25V capacitor across the input, and 100uF 16V across the output. It may also pay to break the +ve line prior to the input capacitor and place a diode there. This will provide more isolation from the other regulators.

They should be placed as close as practicable to the regulator. That means within a cm or so on the board you're using.

Having reviewed everything I think you're hearing whine from the switchmode power supplies and this gets worse as you load up the other regulators.

The pre-amp is the device that is sensitive to this, so you're hearing the noise through there. The rhythmic noise you hear is the beat frequency generated by the regulators operating at a similar, but different frequency.

 

[jeep642]

OK, my suggestion is to replace the regulator you're using for the pre-amp with a liner regulator. Get a 7809. The pin-out is very similar to the modules you're using now.

You should place a capacitor across the input and output of this regulator. I would use a 470uF 25V capacitor across the input, and 100uF 16V across the output. It may also pay to break the +ve line prior to the input capacitor and place a diode there. This will provide more isolation from the other regulators.

They should be placed as close as practicable to the regulator. That means within a cm or so on the board you're using.

Having reviewed everything I think you're hearing whine from the switchmode power supplies and this gets worse as you load up the other regulators.

The pre-amp is the device that is sensitive to this, so you're hearing the noise through there. The rhythmic noise you hear is the beat frequency generated by the regulators operating at a similar, but different frequency.

Sorry for the ignorance but

Which of these for the 7809

Which of these for the first capacitor

Which of these for the second capacitor

If I understand correctly, I just need to "insert" this circuit (7809 and 2 capacitors) on the wire that power the preamp, right?
Will this circuit output 9v or do I need to already have 9v going into the preamp and add this circuit to it?

Thanks very much for the time and help!

 

[(*steve*)]

Sorry for the ignorance but

Which of these for the 7809

All of them. Well, at least the top 10 or so. Get one in a package you can easily use (TO-220 style is best) as this will be a 1A part.

Any of these will be OK. But the one in the plastic case will allow you to bolt it to a geatsink (if it is required) without needing to insulate it.

Which of these for the first capacitor

For this application, pretty much any one is OK. Through hole components will make your life easier, The first one is acceptable.

Which of these for the second capacitor

Try this one.

If I understand correctly, I just need to "insert" this circuit (7809 and 2 capacitors) on the wire that power the preamp, right?
Will this circuit output 9v or do I need to already have 9v going into the preamp and add this circuit to it?

It replaces your current 9V regulator. So the input to it comes from your batteries (or whatever) and the output goes to your preamp.

Thanks very much for the time and help!

No Probs

 

[jeep642]

All of them. Well, at least the top 10 or so. Get one in a package you can easily use (TO-220 style is best) as this will be a 1A part.

Any of these will be OK. But the one in the plastic case will allow you to bolt it to a geatsink (if it is required) without needing to insulate it.



For this application, pretty much any one is OK. Through hole components will make your life easier, The first one is acceptable.



Try this one.



It replaces your current 9V regulator. So the input to it comes from your batteries (or whatever) and the output goes to your preamp.



No Probs

Thanks. I just ordered the parts.

I forgot, what kind of diode should I use?

As soon as I can I will draw a schematic of the circuit I understand you re thinking about. Just to make sure...

Thanks. I hope it'll work!

 

[(*steve*)]

A 1N4001 or anything similar will be OK

 

[jeep642]

Ok, I tried what you suggested Steve but, I'm sorry to say, it didn't work. I got a rather loud buzzing sound using the circuit you suggested to power the preamp.

Now, as I suggested a few posts ago, given that the problem comes from the preamp being connected to the same power source as the camera, monitor, etc... I need to find a way to power the preamp with this same main battery without the preamp being connected to it...

Would this be doable?:

A system with two 9v rechargeable batteries to power the preamp.
One 9v battery would power the preamp while the other 9v battery would be charged by the main battery and when the one powering the preamp falls under a given voltage, the system switches to the other 9v battery while the first one is being charged.
(The "switch" is barely noticeable in the audio. I tried with a "manual" switch)

 

[(*steve*)]

A simpler approach (i.e. less batteries and switching) would be to use an isolated DC-DC converter.

That would provide an isolated DC rail, but I'm not altogether certain it would resolve the problem.

Here is an example. It's not cheap, and I'm not convinced that the noise from this would not be picked up by the preamp (I'm still thinking that's the source).

 

[jeep642]

A simpler approach (i.e. less batteries and switching) would be to use an isolated DC-DC converter.

That would provide an isolated DC rail, but I'm not altogether certain it would resolve the problem.

Here is an example. It's not cheap, and I'm not convinced that the noise from this would not be picked up by the preamp (I'm still thinking that's the source).

I just received a RS-2409SZ/H3.
I searched on the web without success, what's the pin-out?

Thanks!

 

[jeep642]

Nevermind. I found it.