Yes I noted, in fact I subscribe to that thread.
It's just that right now I have another priority, but I have the same ideas to cut out some of the ss switches and the DC-opamps.
One issue I still am unsure about is how fast the autoranger needs to/can react. I guess I would still need the full range input protection for the soundcard this thing is going to feed. I'll burn that bridge when I get to it
Jan
It's just that right now I have another priority, but I have the same ideas to cut out some of the ss switches and the DC-opamps.
One issue I still am unsure about is how fast the autoranger needs to/can react. I guess I would still need the full range input protection for the soundcard this thing is going to feed. I'll burn that bridge when I get to it
Jan
I finally stepped up to the plate and ordered the PCB's to see if they will work. I made one last minute addition to the design. I added LME49610 buffers on the bottom of the board for the outputs. They are set up so they can be easily bypassed but I wanted to try them and see if they can enable a 50 Ohm drive in this.
Boards next week. Maybe some partly working boards soon after.
Boards next week. Maybe some partly working boards soon after.
Is the chip inside the feedback loop?
I'm sure this can drive 50 ohms, no problem, but better if inside feedback loop. I use the BUF634 to drive 32 ohm headphones all the time. I used the TO-220 version with a big heatsink. No problems at all.
The buffer is inside the loop. Its designed to be used that way. I will be interested in how it all actually works once its all together. Datasheet promises .00005%. I won't expect that much from this. The goal is 3V open circuit and 1.5V into 50 Ohms but I'll check the board with 18V supplies with a goal of 7V into 50 Ohms (200 mA Peak)
I pulled the the plug on one of these should be here this week.
Now I don't know if I should have waited for the next hardware
revision or not. I look forward to learning how to use it, mod it
etc. I've read about the card ya'll use and don't know
if I can use what I have not even sure as it's older
and on another computer or look around for an @Juli
as Demian's choice for ease of use.
Either way I'll need to stick a puter on the bench.
I'm reconfiguring that whole area as I need shevling and
organization, etc. Somewhere on here are pics of benches.
I recall Davada posted his bench and I was amazed...
louvered windows in Canada...gotta be cold on that bench.
Cheers,
Now I don't know if I should have waited for the next hardware
revision or not. I look forward to learning how to use it, mod it
etc. I've read about the card ya'll use and don't know
if I can use what I have not even sure as it's older
and on another computer or look around for an @Juli
as Demian's choice for ease of use.
Either way I'll need to stick a puter on the bench.
I'm reconfiguring that whole area as I need shevling and
organization, etc. Somewhere on here are pics of benches.
I recall Davada posted his bench and I was amazed...
louvered windows in Canada...gotta be cold on that bench.
Cheers,
I have Jalousie windows in my shop. A previous owner fell victim to a Jalousie window salesman. There were something like 20 when we moved in. Even with the mild weather here they are really useless. We replaced the most critical ones. I would not know if its my shop sine I have not consciously posted pictures of it, just of stuff in the middle of the mess.
Twas Demian,
#298. Might be good for exhaust fumes.
OR
For a room with a view,
watching the America's Cup Yachts race at 40 knotts.
Sadly, a group of racers from a local sailing club
here in Texas was racing there in the Bay when
they caught a huge gust of wind. Their boat got
knocked down (keel boats get knocked down
while centerboarders capsize), within 10
minutes all has succumbed to hypothermia
and drowned.
Anyway, there was a lot of stuff there in little space.
I rolled my own though, carts that is.
Lighting can be a problem and I was trying to figure out
how to mount a flouresent fixture on a set of sliding drawer roller
guides. That way I could adjust where a broad source of the light
was coming from. There would be no way to put the slides away when
finished though.
I've forgotten what moderate wheather is.
Free associating again, here...go figure.
As the old saying goes, the coldest winter I
remember was the summer I spent in San Francisco.
There is a reason they call it "The City",
but the east bay is warmer.
Down to the night club,
bumpity, bumpity, bump. --Tower of Power, Bump City.
#298. Might be good for exhaust fumes.
OR
For a room with a view,
watching the America's Cup Yachts race at 40 knotts.
Sadly, a group of racers from a local sailing club
here in Texas was racing there in the Bay when
they caught a huge gust of wind. Their boat got
knocked down (keel boats get knocked down
while centerboarders capsize), within 10
minutes all has succumbed to hypothermia
and drowned.
Anyway, there was a lot of stuff there in little space.
I rolled my own though, carts that is.
Lighting can be a problem and I was trying to figure out
how to mount a flouresent fixture on a set of sliding drawer roller
guides. That way I could adjust where a broad source of the light
was coming from. There would be no way to put the slides away when
finished though.
I've forgotten what moderate wheather is.
Free associating again, here...go figure.
As the old saying goes, the coldest winter I
remember was the summer I spent in San Francisco.
There is a reason they call it "The City",
but the east bay is warmer.
Down to the night club,
bumpity, bumpity, bump. --Tower of Power, Bump City.
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QA400 fried?
QA400 - Hooked it up and got the Link, Run
LEDs once. Then Upgraded to latest scope
package.
Did the whole uninstall/reboot/install process
several times to get it working.
However, the USB buss seems to be not work with it
any longer.
USB remains in DISCONNECTED mode no matter
what I do. I only get Left -6 db and Left signal LEDs
illuminating. Beeps when connecting or disconnecting
the QA400 USB.
I'll wait and see what support has to say. Probably
return for another unit I suppose.
QA400 - Hooked it up and got the Link, Run
LEDs once. Then Upgraded to latest scope
package.
Did the whole uninstall/reboot/install process
several times to get it working.
However, the USB buss seems to be not work with it
any longer.
USB remains in DISCONNECTED mode no matter
what I do. I only get Left -6 db and Left signal LEDs
illuminating. Beeps when connecting or disconnecting
the QA400 USB.
I'll wait and see what support has to say. Probably
return for another unit I suppose.
OS QA400
@Demian
Its Win Vista HomeEdition on Fujitsu Laptop.
I think I corrupted the drivers on it when I upgraded
and I reloaded the drivers. I think it's a known issue.
QA must have steps to update drivers or something.
Thats the portable puter.
The old Fry's 'puter which I had to rebuild, etc
I tried the QA400 with these results:
That's in loopback mode after "calibration" and while I thought
I had 1000 Hz, it's on 4000 Hz.
So I dragged the HP339a out, as received, not even cleaned yet.
I put her on the QA400 and these are the results from the output,
600 ohm .3V to the input of the QA400, left channel.
These are just plugged into the side of the computer's USB port.
So now I have a base line for the QA400 and HP339a on Frys 'puter.
I'll have to go back now and see what you guys are doing to the
HP339A and QA400 to see what I need to do to get them better.
I see the noise in the source 1000 Hz and the 2nd, 3rd harmonics.
Turning the frequency level raised then about 10 db for 2nd
and 15 or more db for the 3rd.
Today, right now is the first time I've ever attempted to measure anything like
this, and is the first time I've looked at the HP339a...other than on a Fluke hand held meter.
@Demian
Its Win Vista HomeEdition on Fujitsu Laptop.
I think I corrupted the drivers on it when I upgraded
and I reloaded the drivers. I think it's a known issue.
QA must have steps to update drivers or something.
Thats the portable puter.
The old Fry's 'puter which I had to rebuild, etc
I tried the QA400 with these results:
That's in loopback mode after "calibration" and while I thought
I had 1000 Hz, it's on 4000 Hz.
So I dragged the HP339a out, as received, not even cleaned yet.
I put her on the QA400 and these are the results from the output,
600 ohm .3V to the input of the QA400, left channel.
These are just plugged into the side of the computer's USB port.
So now I have a base line for the QA400 and HP339a on Frys 'puter.
I'll have to go back now and see what you guys are doing to the
HP339A and QA400 to see what I need to do to get them better.
I see the noise in the source 1000 Hz and the 2nd, 3rd harmonics.
Turning the frequency level raised then about 10 db for 2nd
and 15 or more db for the 3rd.
Today, right now is the first time I've ever attempted to measure anything like
this, and is the first time I've looked at the HP339a...other than on a Fluke hand held meter.
@Demian
Its Win Vista HomeEdition on Fujitsu Laptop.
I think I corrupted the drivers on it when I upgraded
and I reloaded the drivers. I think it's a known issue.
QA must have steps to update drivers or something.
Thats the portable puter.
The old Fry's 'puter which I had to rebuild, etc
I tried the QA400 with these results:
That's in loopback mode after "calibration" and while I thought
I had 1000 Hz, it's on 4000 Hz.
So I dragged the HP339a out, as received, not even cleaned yet.
I put her on the QA400 and these are the results from the output,
600 ohm .3V to the input of the QA400, left channel.
These are just plugged into the side of the computer's USB port.
So now I have a base line for the QA400 and HP339a on Frys 'puter.
I'll have to go back now and see what you guys are doing to the
HP339A and QA400 to see what I need to do to get them better.
I see the noise in the source 1000 Hz and the 2nd, 3rd harmonics.
Turning the frequency level raised then about 10 db for 2nd
and 15 or more db for the 3rd.
Today, right now is the first time I've ever attempted to measure anything like
this, and is the first time I've looked at the HP339a...other than on a Fluke hand held meter.
Add a bit of averaging to squish the noise down. Build a notch filter. Then it gets impressive.
David,
You mean something like this:
Higher resolution and then averaging at 30x so that I can now see the
harmonics.
Is that representative of the real noise floor now?
Or
Averaged down to a line?
Maybe both.
I was going to try and build that notch that Demian, Richard, ghg,
did you make one too, the funky blue box? (Brool-in-Cool)?
You mean something like this:
Higher resolution and then averaging at 30x so that I can now see the
harmonics.
Is that representative of the real noise floor now?
Or
Averaged down to a line?
Maybe both.
I was going to try and build that notch that Demian, Richard, ghg,
did you make one too, the funky blue box? (Brool-in-Cool)?
Last edited:
David,
You mean something like this:
Higher resolution and then averaging at 30x so that I can now see the
harmonics.
Is that representative of the real noise floor now?
Or
Averaged down to a line?
Maybe both.
I was going to try and build that notch that Demian, Richard, ghg,
did you make one too, the funky blue box? (Brool-in-Cool)?
NO I did one of Dick Moore's. I needed to cover a wider band of frequencies.
I might do some fixed frequency notched at spot frequencies.
Bring the level down to about -40dB then you will see more like what it is with a notch.