INA 217 Mic Preamp Circuit

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Liutmod

Well-known member
Joined
Sep 16, 2016
Messages
61
Hello I'd like to realize some INA217 mic preamps
On the net I found several circuits but I am not sure how they work
Someone can provide me a good tested  schematic?
 
Liutmod said:
Hello I'd like to realize some INA217 mic preamps
On the net I found several circuits but I am not sure how they work
Someone can provide me a good tested  schematic?
The datasheet has everything you need.
 
A thing I have not clear it is because some circuits have the OPA 137 and others no
What's the difference?
 
In this site it is offered a PCB for this preamplifier, but it doesn't inclde the OPA 137

http://www.bluecomtech.com/Web%20Sites/OSH%20Park/oshpark.com/shared_projects/QbTViZlZ.html
 
If you look at figure 16, it says the OPA137 is part of an 'optional DC control loop'.  It is a DC servo that works to keep the output potential at DC 0V.

Do a Google search for 'dc servo tutorial' to learn more about it.  I found it wasn't needed when I built this circuit in the past.
 
http://twin-x.com/groupdiy/displayimage.php?pos=-190
Built ,tested and working.
 
I have found this simpler schematic with THAT1510
Anyone knows if it is possible to add a transformer to the output?
 

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Liutmod said:
I have found this simpler schematic with THAT1510
Anyone knows if it is possible to add a transformer to the output?

Of course it's possible . But the questions are why you want to and consequently what is the best way to implement it...
 
I want to add the transformer to balance the output ... without complicating the circuit

I'd like to use something not too expensive like OEP A262A2E

Consider I'd use these preamps essentially for external drum recordings
 
I know but I'd prefer to put a  transformer if there are no contraindications

In the output of the THAT1510 (pin 6) may be better to put a capcitor?
 
Yes you can put a transformer on the output.  Jensen and Cinemag are good resources for transformer application notes, as there some details that are important.
 
It's not the best choice.  The main issue is ICs are generally not good at heavy lifting,  so you would be asking a lot of the 1510 by putting that on its output.  You definitely don't want a step up transformer (1:2), you could wire it 1:1 but you are then still limited  by its inductance.

You could get a  good 1:1 transformer for $30-40.

Edit: if you wanted something inexpensive to try A262A7E would be a better choice.  Though you would still have a good bit of low frequency distortion with these.
 
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