Trying to make a Balanced line input on LM3886 chipamp using ina134. HELPPP!!!

[sonicalleystudios]

Andrew T, the ina 134 does exactly what the typical balanced input shows in an003 doc. I was just powering the chip wrong.

 

[sonicalleystudios]

I've decided to tap off the DC output voltages on my power supply board and use the LM7818/7918 regulators to bring the voltage into range for the chip to run properly on the balancing circuit. Does anyone know a chip that would be better suited for a higher voltage? My next amplifier will be using 35vdc outputs and i'll still need to get it down to 18v. I would assume I'd probably fry those regulators.

 

[AndrewT]

the maximum voltage difference across the LM317/337 voltage regulators is ~35Vdc.
They can be used on much higher supply voltages. You as "designer" must ensure that the voltage difference never exceeds that specification limit.

A Zener across the IN/OUT can provide some overvoltage protection.

 

[sonicalleystudios]

Do you know if there is an "inside the box" version like like lm78xx series? My plan is to solder the output directly onto the circuit board input to simplify connecting the power to it. Having resistors and things needed on the output changes the ability to do that

 

[AndrewT]

download the datasheet.

 

[mjf]

I've decided to tap off the DC output voltages on my power supply board and use the LM7818/7918 regulators to bring the voltage into range for the chip ........;

if you only need a few mA of current you can try out the 78Lxx series (e.g.
uA 78L15, 78L18 and so on.)
application see datasheet.

 

[Redshift187]

If the INA circuit is going inside the same case as the LM3886, you may be able to just use the power supply that the LM3886 is using. What are the *measured* voltages powering the LM3886?

 

[sonicalleystudios]

hey all, i just received my lm7815/7915 regulators and tried to hook them up. im not getting a negative voltage from the 7915 chip and it is getting really hot. The 7815 is getting the proper +15v dc on its output and is barely warm. I've tried 2 chips. I must be missing something...

I have the v+ from my power supply going to the 7815 input, and the v- from the power supply board going to the input of the 7915.

any ideas?

 

[mickeymoose]

I did not follow this thread, so this may have been covered before.
The 78 series has a different pin-out arrangement than the 79 series regulators. You may also need a dropping resistor at the input of the regulator to reduce device power dissipation. E

 

[turk 182]

without details of all the supply parts and how you've wired things together i'd hazard a guess that the 7915 is being fed the wrong polarity of voltage.
i think the missing "something here" is a slightly better understanding of bi-polar power supply circuits.
any chance you can upload pic's or a full schematic of what you currently have so we can help you sort this out.
simple things can create confusing problems and overlooking details can lead to frustration when things aren't working the way they should.

 

[sonicalleystudios]

Nope definitely understand bipolar supplies, it ended up MickyMoose was right. I had the regulator (7915) wired wrong. The pins are different than the 7815.

All is working well now! Thanks everyone for the help...and the criticism even though it was a little bit undue at points