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balanced headphone protector


kevin gilmore
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  • 9 months later...

Hi guys

To power the board what is the best method or only method?

For example if i am using a GRLVs for my Dynahi should i have three power supplies one for each amp board and another for the protection board?or there is another way that i am missing?

Don´t hit me in the face if this is a noob question eh eh

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Just power it from one of the amp PSUs, though I can't remember what the Protector's input voltage limit is. I assume your Dynahi is at +/-30? Check on the Protector...

EDIT: the boards have 7812/7912 regs on them, so the input voltage limit would be 35 Vdc.

 

 

Sent from my iPhone using Tapatalk

 

Edited by Pars
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10 hours ago, Pars said:

Just power it from one of the amp PSUs, though I can't remember what the Protector's input voltage limit is. I assume your Dynahi is at +/-30? Check on the Protector...

EDIT: the boards have 7812/7912 regs on them, so the input voltage limit would be 35 Vdc.

 

 

Sent from my iPhone using Tapatalk

 

Thanks Pars. Yes 30v. So there is no problem if I join two wires in the same output of one of the amps psu? By the way, do you have any of your boards that you could sell it to me? The Led is nice addition that I could use.

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  • 6 months later...

Kevin,

Want to build this board and try it instead of e12. Few questions if you allow:

Is trigger offset DC with standard resistors 0.5v? Is it from O+ to O- or from O+ to GND/O- to GND?

Is it suitable for non-differentail balanced amps like 4-board B22, 2-board KSA5?

Is it suitable for SE amps (like 2-board B22, 1-board KSA5)? Just use R+ and L+ terminals?

Input GND taken from where? If it's signal GND, then take it from any board? Can it be left unpopulated?

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  • 3 years later...
  • 1 year later...

I found a backplate for Neutrik NC4FAV at oshpark.com.

But I think I also need some protection for the dynamic headphones…

Snapshot_22-08-22_15-12-57.thumb.jpg.ef04cefecd45a2b61038a6eac7535cf7.jpg
Snapshot_22-08-22_15-12-28.thumb.jpg.56969d0c966a9e0c7d1cf8fcccfcb6c8.jpg

…schematically same as Kevin’s protect3. Board size 2.75in x 1.95in. With a little creativity the board can probably be made a bit smaller.

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  • 1 month later...

 

922763553_IMG_0502(002).thumb.jpg.c60d5a381aba858a979f8f187d78b3f5.jpg234512577_IMG_0503(002).thumb.jpg.a91a16f2b06d2c2a86194c9cec236a4f.jpg

Seems to work. The red LED turns off and on correctly. Red light means everything is OK – off means something is bad.  A green LED might be more appropriate.

The short uninsulated wires, one each side, is not to correct a mistake. It was the only way I find to get it working. The board has 19 vias. I did one mistake though. I gave the mosfet driving the relay a wrong footprint, but fortunately it was possible improvise… now it works as it should.

I’m waiting for the relay. Omron G6S-2G – surface mounted, good for 2 A.

 

Edited by JoaMat
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Next build – remove R1 ( don’t understand why I put it there – maybe because I’m an amateur) and R2 value is far too low, unless you want 40 mA through LED, so I switched to 1K.

IMG_0506.thumb.jpg.5d2757599cd259a8bd809fd68147afb9.jpgIMG_0507.thumb.jpg.db181e4422812db87e7cb7f822c36dbb.jpg

Small board 19mm x 15mm with the 555, a small PNP , three resistors and of course the bi color LED. Works perfect.

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During the last weeks I’ve built a few versions of the headphone protector. One small problem is voltage regulators, 7812 and 7912. Output voltages might differ more than 100mV from “specified “. 7812 at +12.1V and 7912 at -11,9V will move intended references 100mV. To tackle the problem, I made this resistor string.

Snapshot_22-10-07_10-05-54.thumb.jpg.41f8b41c3e951a3851626d11ad5f80ca.jpg

With above resistor string I can handle any deviations of the voltage regulators up to 200mV. If you want something else than +/-60mV trigger points, change the 1K resistor. 2K instead of 1K gives you +/-120mV.

I’ve enjoyed working with this protector project a lot. Thanks for designing this Headphone Protector, Kevin.

Edited by JoaMat
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  • 2 weeks later...

It’s not very clear in the schematic above (I’m sorry), but D15 and D16 is a bi color LED with common cathode. Below the two LEDs are replaced with a bi color device.

 Snapshot_22-10-19_10-55-46.jpg.f5aee056dc184956c336b969f2087391.jpg

The purpose of the 555 is make the LED red when relay is disengaged and green when engaged.

This is the way I found to get a simple red/green indicator working. 

On 10/3/2022 at 7:20 PM, JoaMat said:

IMG_0506.thumb.jpg.5d2757599cd259a8bd809fd68147afb9.jpgIMG_0507.thumb.jpg.db181e4422812db87e7cb7f822c36dbb.jpg

Small board 19mm x 15mm with the 555, a small PNP , three resistors and of course the bi color LED. Works perfect.

 

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