DC Servo MOSFET Amplifier

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#462
AndrewT said:
this is unusually high unless there is a severely unbalanced load on the two supply rails. I typically see 0Vdc to 0.2Vdc difference in supply rails from my transformers. I think you need to investigate further.This is too slow.
one or two seconds to trip for <2Vdc offset is usual for a competent offset detector. 4 to 5V of offset should give near instantaneous tripping, maybe <<0.5seconds.
10V offset should sound instantaneous.

This detector should NOT trip with a continuous 20Hz @ maximum sinewave at it's input.
Click to expand...

I am not saying what it should or shouldn't do. I am reporting what it does do. My only explanation for the difference in voltages is that the positive rail passes through two 1R resistors but the negative rail doesn't. It is direct. These tests were performed with no load attached so that may change once I hook up the amp to it. I was a little surprised that it took so long to trip. I initially tested the DC trip function using the 15v from the little auxiliary circuit. It takes maybe 1/2 a second to trip. Then I used a little DC power supply that I have that produces 1.5v increments starting at 3v. As I said, 3v won't trip it but 4.5v will but it takes 2-3 seconds. With each jump in voltage it reacts a little quicker. I'm not sure how the short circuit protection is supposed to work but I tried shorting the speaker in and the speaker out Jacks and none of them would cause it to trip.
 
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#465
vargasmongo3435 said:
Terry can you show the image of where the "1R 5W" is located I'm confuse 😕

Regards
Juan
Click to expand...

See attached.

I just replaced the 1R with 0R1 and see no change. I read +64.4vdc/-64.9vdc. I even tried reversing the AC leads from the transformer with no change.
 

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  • APEX PSU+Protect 0R1 resistors.jpg
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#466
still4given said:
See attached.

I just replaced the 1R with 0R1 and see no change. I read +64.4vdc/-64.9vdc. I even tried reversing the AC leads from the transformer with no change.
Click to expand...


Check those 2N5401 maybe one of them are no as matched as the other one " I think that might be the reason"

this probably change after load is apply with the F100's so the difference is just -0.5V on the negative rail
 

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  • APEX F100PSU PCB.jpg
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#467
vargasmongo3435 said:
Check those 2N5401 maybe one of them are no as matched as the other one " I think that might be the reason"

this probably change after load is apply with the F100's so the difference is just -0.5V on the negative rail
Click to expand...

Both + rails read the same so I doubt it is the 2N5401. It is probably because the + rail had that additional circuitry connected and the - rail just goes directly out. I doubt the amp will care about a 1/2v difference, I just wanted to report my findings.
 
#469
The sight difference in +Vsup and -Vsup is ok, and is expected with this supply when loaded, the 0.1R resistors look like the current sensing resistors. The project only monitor the positive trails for over current protection.

Terry are you using same pcb as post 466

This circuit should trip when to much current is drawn from + supply rail. If not drawing current it won't trip
 
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#474
Playing with Sprint

I have been trying to learn Sprint. Juan Vargas has been helping me by loaning me file to practice with. So I used his template for the F100 and made a try at the FX100. Have a look and see if you find errors.

Thanks, Terry
 

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  • FX100 PHOTO.jpg
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#475
I reduced the board sizes a little. One small enough to qualify for prototype discounts.

Still waiting for Mile to give it a look to make sure it follows the circuit faithfully.
 

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  • FX100 PHOTO 81mm X 84mm.jpg
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  • FX100 PHOTO IRFP.jpg
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#478
Had to lookup Sprint's abilities, some thing to be said about a layout package with no linkage/checking to a schematic or a netlist.
Not sure why anyone would use such a tool when you can use something with more functionality such as Eagle?
 
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#480
Well I do not use Eagle much either, I use orcad but that is not for free.
I tried Eagle and thought it was not very easy to learn either and I have used many cad pkgs.
Every cad tool has its own mind set, so they all take time, some times lots of time, to get into the head space for sure.
Just I hate to see folks use a cad pkg with limited or no checking between sch/layout, as it is very time consuming and a very error prone process. To be avoided unless know other solution exists.
I can help you learn eagle or anything else that we both can use. I know Jeff W is using diptrace which seems just as capable as Eagle, might want to give it try and see what you think.
Probably best to start a new thread on cad tool usage.
 
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