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A suitable mic amp chip with ALC/Limiter


 

https://www.njr.com/electronic_device/products/NJM2783.html

Cheers

--
Raj, vu2zap
Bengaluru, South India.


 

Very interesting chip.
Have you any idea how to use it?


 

You could try just building the application diagram on page in the pdf. You will need to
reduce the out to suit ubitx with a preset.

At 01/10/2020, you wrote:
Very interesting chip.
Have you any idea how to use it?


 

on Page 5


 

At 01/10/2020, you wrote:
Very interesting chip.
Have you any idea how to use it?


Ravi Miranda
 

Thanks Raj, just ordered it. :-)

On Fri, 2 Oct 2020 at 06:05, Raj vu2zap <@Raj> wrote:

Here is one project

http://ja9cde.la.coocan.jp/page231.htm


At 01/10/2020, you wrote:
Very interesting chip.
Have you any idea how to use it?




--
I'm here to add more value to the world than I'm using up.


 

Ravi,

They have a dual/stereo version that can be used to uBitx.. one 1/2 for RX and
the other 1/2 for TX!

Remeber to include a preset to reduce output to suit uBitx.

Raj

At 02/10/2020, you wrote:
Thanks Raj, just ordered it. :-)

On Fri, 2 Oct 2020 at 06:05, Raj vu2zap <@Raj> wrote:

Here is one project

http://ja9cde.la.coocan.jp/page231.htm


At 01/10/2020, you wrote:
Very interesting chip.
Have you any idea how to use it?


Ted
 

Another approach - Get one of these, remove the mic element and lead that to your own mic input:

https://www.ebay.com/itm/MAX9814-Electret-Microphone-Amplifier-Module-Auto-Gain-Control-AGC-for-Arduino/324232313537?hash=item4b7dc07ac1:g:zzsAAOSw3L1fERB9



I prefer this one, though, as it seems to have better compression options with attendant sensitivity levels. One can have low to medium sensitivity, but have high compression within that threshold. Experimentation is key.  As an option, provide a 1 or 2k resistor from B+ to the high side to maintain the bias that the mic's used to:

https://www.ebay.com/itm/1pcs-NEW-MAX9814-Electret-Microphone-Amplifier-with-AGC-Function/222133457754?hash=item33b82f935a:g:uSYAAOSwepZXSpnI



I use the latter in both of my V5's, though the former does work and fits into a small mic case if desired.

-Ted
K3RTA


 

Thanks for schematic !


iz oos
 

Would you think It could also be used as a audio AGC?


Il ven 2 ott 2020 05:56 AM Raj vu2zap <rajendrakumargg@...> ha scritto:
You could try just building the application diagram on page in the pdf. You will need to
reduce the out to suit ubitx with a preset.

At 01/10/2020, you wrote:
>Very interesting chip.
>Have you any idea how to use it?







Ted
 

Is,


I had played with the use of a MAX9814-based mic compressor as an AGC circuit, prior to learning about the ND6T-based boards and the commercial product available.

Just remember that you're working with low audio values to begin with:  One would disconnect the audio line going to the volume potentiometer and connect it to the input of the compressor circuit. DC isolation is important if you're using one of the boards I referenced earlier - because of bias voltage provided for the intended use with an electret mic element. 

The output really ought to pass to a 10K trim pot before being re-connected to the radio's volume pot again. Just keep in mind that an audio-only "AGC" doesn't prevent the radio's front end from being overloaded; it just keeps the audio going to your speaker or headphones at a more or less even level (which is certainly nice to have, however it's achieved).  Think of this as a more advanced version of the LED-driven toward a photocell for attenuation of the audio path. Here, it's all on one board and has changeable compression and level options.

Personally, I'd not bother with using a microphone compressor as an AGC. The Kit-Parts option is easy enough to install, and, it attenuates at the RF level where it should be done.




Best wishes,

Ted
K3RTA


iz oos
 

Hi Ted, thanks for the detailed reply. I will implement it probably as a separate box to be possibly connected to any other no-AGC qrps.


Il ven 2 ott 2020 07:43 PM Ted via groups.io <k3rta=yahoo.com@groups.io> ha scritto:
Is,


I had played with the use of a MAX9814-based mic compressor as an AGC circuit, prior to learning about the ND6T-based boards and the commercial product available.

Just remember that you're working with low audio values to begin with:  One would disconnect the audio line going to the volume potentiometer and connect it to the input of the compressor circuit. DC isolation is important if you're using one of the boards I referenced earlier - because of bias voltage provided for the intended use with an electret mic element. 

The output really ought to pass to a 10K trim pot before being re-connected to the radio's volume pot again. Just keep in mind that an audio-only "AGC" doesn't prevent the radio's front end from being overloaded; it just keeps the audio going to your speaker or headphones at a more or less even level (which is certainly nice to have, however it's achieved).  Think of this as a more advanced version of the LED-driven toward a photocell for attenuation of the audio path. Here, it's all on one board and has changeable compression and level options.

Personally, I'd not bother with using a microphone compressor as an AGC. The Kit-Parts option is easy enough to install, and, it attenuates at the RF level where it should be done.




Best wishes,

Ted
K3RTA