SD49225-HNI microphone inst. 9v batt.

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Pmedicj

Getting the hang of it
Apr 8, 2018
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I installed this microphone https://www.amazon.com/VideoSecu-Se...2&sprefix=ip+camera+mic&sr=8-9&ref=mp_s_a_1_9to my PTZ and tried a wall wart 12vdc 150mah and was getting all sorts of static / clipping. I believe the wall wart was the cause so I was digging through a junk drawer and found a 9 volt battery lead and then sctartched my head a moment and wired it up, plugged in the battery and wa la...Fantastic audio! I mean way better than my microseven I have on another camera.
It’s been going strong for a couple days now, curious to see how long it will last.
If it is short lived any recommendations on a good wall wart that will work without so much interference?
 
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Pmedicj said:
I installed this microphone https://www.amazon.com/VideoSecu-Se...2&sprefix=ip+camera+mic&sr=8-9&ref=mp_s_a_1_9to my PTZ and tried a wall wart 12vdc 150mah and was getting all sorts of static / clipping. I believe the wall wart was the cause so I was digging through a junk drawer and found a 9 volt battery lead and then sctartched my head a moment and wired it up, plugged in the battery and wa la...Fantastic audio! I mean way better than my microseven I have on another camera.
It’s been going strong for a couple days now, curious to see how long it will last.
If it is short lived any recommendations on a good wall wart that will work without so much interference?
Click to expand...

I am using the Microseven with a 12v 1a wall wart with extension cable and get great audio.
Its a cheap no name wall wart I picked from a electronics shop.
 
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looney2ns said:
I have one of those Mics, I was never able to get it to work without AC hum in the background.
I second the Microseven.
Click to expand...

I just tried another wall charger with horrible hum and static. The 9v battery absolutely does the trick, Probably the best sounding mic I have hooked up this way. I may try the microseven with a 9v depending on how long this one lasts.
 
I cant imagine that they MIC draws much power. Likely less than 10ma. If the 9V battery makes it all good and the 12V AC/DC brick is noisy, a simple passive low pass filter should clear it up, single or two stage. I would grab a 16V rated electrolytic (maybe 220uf) and a 1uF ceramic and a couple of 10 ohm 1/8W resistors and make a two stage in series with the power supply (resistor-220uF cap, resistor -1uF cap, and draw power from across the 1uF cap, which draws from across the 220uF, with power injected at the first 10 ohm resistor), but almost anything that is lying around should work.
 
Measure the current draw of the microphone. Very often, this type of microphone uses an "electret condenser" microphone capsule. And due to the incredibly high output impedance of a tiny condenser element, they use a FET or low-power, high input impedance Op Amp to buffer the signal so it will work with typical 600 ohm systems. But that's the only thing that draws any current in the system.

As a result, these microphones usually draw very little current. Frequently well below 1 mA. But measure yours to be sure.

Also, check the documentation to see what range of voltages the microphone is designed to use.

Let's assume that the mic draws 1mA of current. If we can live with, perhaps, 2 Volts of voltage loss in our filter, you can increase the value of your filter's resistors to be 1K each. You will still want higher value capacitors, but at least they won't need to be huge!

Using a couple of 1K resistors and a couple of 2200uF caps, you might get rid of the 120Hz ripple fairly well.

Of course, this low current drain also means that a battery will last quite a while, too.

And you may find that the current draw of the mic is even lower than our 1mA figure, so you could use even higher value resistors.

Another option is to build a simple series voltage regulator circuit for the mic. I still like the venerable LM317 adjustable regulators for a lot of audio uses. They're surprisingly fast, so they're suitable for "hi fi" use when you bypass them properly with high-quality capacitors. They'd certainly be just fine for one of these mics. You can get the small TO-92 package LM317LZ versions for very cheap. Add a couple of resistors and a couple of caps, and you've got a very respectable voltage regulator suitable for this use. It might actually end up being cheaper than the higher value capacitors you'd end up needing to use to build a passive filter.

And finally, some small wall-warts actually have decent linear regulators built into them, and can be quiet enough on their own for this sort of use.

Sometimes having high quality audio is quite important for a security camera setup. So it may be worthwhile to provide a good clean supply for the microphone.

This all makes me wonder if there would be a market for a good quality microphone with built in compression amplifier made to plug into these security cameras. Having the audio already compressed before it hits the camera could eliminate that annoying clipping (hard limiting) that you tend to get when a loud vehicle goes by, or the wind hits the mic. We tend to worry a lot about the video quality from our cameras, and then blow off the audio end of things. But it can be important.
 
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Pmedicj said:
I installed this microphone https://www.amazon.com/VideoSecu-Se...2&sprefix=ip+camera+mic&sr=8-9&ref=mp_s_a_1_9to my PTZ and tried a wall wart 12vdc 150mah and was getting all sorts of static / clipping. I believe the wall wart was the cause so I was digging through a junk drawer and found a 9 volt battery lead and then sctartched my head a moment and wired it up, plugged in the battery and wa la...Fantastic audio! I mean way better than my microseven I have on another camera.
It’s been going strong for a couple days now, curious to see how long it will last.
If it is short lived any recommendations on a good wall wart that will work without so much interference?
Click to expand...
Ordered this.. I'm getting some hum on my micro seven mic using wall adapter
 

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There are pros and cons to using a battery. The con is that they run down and need to be replaced. And 9V batteries are expensive and wimpy. So they can end up being an expensive solution.

The good side of using batteries is that they eliminate several sources of noise. They end up being completely isolated or "floating" with respect to any ground or "audio low". This eliminates ground loops and thus, one large and common source of hum and noise.

The other thing is that they are inherently quiet and ripple-free. So they can provide a very clean power source.

There have been some high-end stereo preamps and other devices that use batteries for those reasons. One preamp I remember charged the batteries when you switched the unit off, then ran entirely on the batteries when you switched it on.
 
Just as info, I'm powering 3 of the microseven mics (i.e. different mic) with POE power and there are no problems. Some wall warts give good, clean DC power, and some don't. The undesirable ones have a high output voltage with little or no load (I've seen them up to 18 volts for a 12 volt wall wart), and/or a "dirty" output. Another issue is if the output is fully isolated. One that isn't isolated could easily be a hum source. It's worth trying different wall warts if you have them available.
 
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tigerwillow1 said:
Just as info, I'm powering 3 of the microseven mics (i.e. different mic) with POE power and there are no problems. Some wall warts give good, clean DC power, and some don't. The undesirable ones have a high output voltage with little or no load (I've seen them up to 18 volts for a 12 volt wall wart), and/or a "dirty" output. Another issue is if the output is fully isolated. One that isn't isolated could easily be a hum source. It's worth trying different wall warts if you have them available.
Click to expand...
What you using to poeer poe? Splitter?
 
I'm powering one of the microseven mics using a POE splitter, and the other two using the camera's internal power, similar to what guykuo posted. My cameras aren't PTZ like you and guykuo have, so my mod might not be applicable, but I'll add the link at the end of the message anyway.

I bought a mic that looks the same as yours (not the same one, however) and its performance was nowhere near the microseven. It's sitting in the closet in the pile of parts that will likely never get used. After your comparison with the microseven I wish I had one like yours to tinker with, but since I'm all set up and working fine I won't bother.

Here's the camera modification link. I've done this to 4 different model cameras (none are ptz), both chinese market and international, and so far they all use the same diode to block the internal power from going out the 12 volt power in line. Dahua camera mod to power external IR light
 
tigerwillow1 said:
I'm powering one of the microseven mics using a POE splitter, and the other two using the camera's internal power, similar to what guykuo posted. My cameras aren't PTZ like you and guykuo have, so my mod might not be applicable, but I'll add the link at the end of the message anyway.

I bought a mic that looks the same as yours (not the same one, however) and its performance was nowhere near the microseven. It's sitting in the closet in the pile of parts that will likely never get used. After your comparison with the microseven I wish I had one like yours to tinker with, but since I'm all set up and working fine I won't bother.

Here's the camera modification link. I've done this to 4 different model cameras (none are ptz), both chinese market and international, and so far they all use the same diode to block the internal power from going out the 12 volt power in line. Dahua camera mod to power external IR light
Click to expand...
Oh nice.. im not attempting that haha
 
RicRat2009 said:
I am using the Microseven with a 12v 1a wall wart with extension cable and get great audio.
Its a cheap no name wall wart I picked from a electronics shop.
Click to expand...
I tried the 9v battery and mic sounds awesome now.. no hum.. All the ones i have are 12v 2A.. So maybe i need to get a 12v 1A like you

Update: After doing some digging.. i found a 12v .75A adapter. Works great.. Thanks fellas
 
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Waldo said:
Do you have a link or description/name for the 12V .75A adapter?
Thanks
Click to expand...
Found it in a box of old adapters had laying around.. brand is motorola.. im guessing any brand will work as long as its 12v and 1A or .75A
 
Cameraguy said:
I tried the 9v battery and mic sounds awesome now.. no hum.. All the ones i have are 12v 2A.. So maybe i need to get a 12v 1A like you

Update: After doing some digging.. i found a 12v .75A adapter. Works great.. Thanks fellas
Click to expand...
Also, with the wall wart, I had a humming and poor sound with passing vehicles. Used AAC, turned off noise filter and mic volume down to 30.
Now I can hear people across the street and vehicles sound normal.
 
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