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Homebrew Digital Sampling Audio spectrum analyser.
Homebrew Digital Sampling Audio spectrum analyser.
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Old 10th April 2009, 07:32 AM   #131
GK is offline GK  Australia
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Hi Alan.

The boards are 90% complete. I was going to use a rotary switch for the time base but the decoding is too much of a hassle and I've got no spare I/O pins on the uC to take 15 direct inputs.

The INA118 gain is set to only 1.25 (2V FSD). An external interface will be needed to interface with the outside world.
In other words, the ADC module input is not designed to connect to devices under test.

Because I want to use this unit as either a LF DSO or the recorder/display end for a sweeping frequency spectrum analyser, I'm keeping it modular. As it is, the instrument will be pretty useless on its own.

I like the old school Tek analogue scopes, but never prefered their DSO's over the competition. Opted for a LEcroy for my bench at work

Cheers,
Glen
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Old 11th April 2009, 09:05 AM   #132
GK is offline GK  Australia
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Here is the completed motherboard. I used DIP'ed devices for the IC's and SMD for most of the passives. I could have easily made it 1/4 the size if designed to be manufactured at a board house, but I had to keep it homebrew friendly with tinned wire feed-throughs instead of plated through holes.
There are so many parallel address and data lines that you have to keep to a minimum via size and track width / clearance to ensure success. You also have to return tracks to component pads on the layer that a soldering iron can get too. Anyway, like with the VGAASAMK1 project I’ve erred on the conservative side and this board will be a piece of cake to make / hand-drill and load.

I made a slight modification to the motherboard schematic also, in that the SMD memory chips have been put onto a pair of “memory module” daughter boards that plug in to the motherboard vertically via 90-degree SIL headers. The paralleled address line routing was getting too much of a mess.

There is also another daughter board which I forgot to mention before – the “DAC module” which provides the 0-10V ramp output, synchronised to the recorder section timebase for controlling an external analogue VCO for spectrum analyser applications.

The RS232/comms module and the timebase display module are separate from the motherboard and will mount behind the instruments front panel.

The design work is complete but it will take at least a couple of week before I have this thing up and running as 50% of the parts I need are on back order. Farnell Aust. seems to be keeping an ever-dwindling inventory of in-stock items.

In the meanwhile I will start up loading the final schematics onto my website under test equipment, DSOMK1.

When it’s running I’ll post some RF spectrum analyser displays that I’ll be able to immediately generate with some existing equipment.

Cheers,
Glen
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Old 11th April 2009, 09:15 AM   #133
GK is offline GK  Australia
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And the bottom layer....
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Old 11th April 2009, 09:34 PM   #134
VivaVee is offline VivaVee  New Zealand
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Quote:
Farnell Aust. seems to be keeping an ever-dwindling inventory of in-stock items.
They also laid off 200 staff - including our local rep. Still, you have next day delivery for what is in stock
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"If you can not measure it, you can not improve it" - Lord Kelvin
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Old 6th June 2010, 09:43 PM   #135
johngalt47 is offline johngalt47  United States
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Homebrew Digital Sampling Audio spectrum analyser.
Any updates?
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Any technology sufficiently advanced is indistinguishable from magic
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Old 7th June 2010, 01:22 AM   #136
Bonsai is offline Bonsai  Europe
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I don't think glen is with us anymore - his account has been disabled.

Although occasionaly a bit direct and absolutely dissmissive of subjectivist b.s., he did bring some great technical insights to the forum.
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Old 7th June 2010, 10:50 AM   #137
jacco vermeulen is offline jacco vermeulen  Netherlands
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Technical insight usually refers to direct and dissmissive of subjectivist B.S.

Glen's car talk is dearly missed, even more than the B.S. Flag smiley.
(Geez, one isn't even allowed to write B and S together anymore)
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Old 7th June 2010, 12:06 PM   #138
Bob Cordell is online now Bob Cordell  United States
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Originally Posted by Bonsai View Post
I don't think glen is with us anymore - his account has been disabled.

Although occasionaly a bit direct and absolutely dissmissive of subjectivist b.s., he did bring some great technical insights to the forum.
This is a deep loss for DIYaudio. Glenn is top-notch. None of us is perfect, and Glenn's contributions far outweigh any controversy or directness he brought. A bit of conflict and disagreement is good. We all learn from the back-and-forth. I hope Glenn will return.

Cheers,
Bob
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Old 15th June 2010, 03:22 PM   #139
PB2 is offline PB2  United States
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Originally Posted by Bob Cordell View Post
This is a deep loss for DIYaudio. Glenn is top-notch. None of us is perfect, and Glenn's contributions far outweigh any controversy or directness he brought. A bit of conflict and disagreement is good. We all learn from the back-and-forth. I hope Glenn will return.

Cheers,
Bob
I agree Bob, it is also unfortunate to see Syn08 Binned again. Seems they don't want real competent engineers here. I have told other friends that people don't appreciate real work unless they have to pay for it. Imagine what one would have to pay to get Syn08's designs under contract ... LOL! I believe that we're seeing bias against real degreed engineers here and that is unfortunate.

I have considered putting some of my work on forums in the past, but I hold back and do very little since it is not often appreciated.
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Old 15th June 2010, 06:33 PM   #140
Bonsai is offline Bonsai  Europe
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I agree with the comments above.

Last edited by Bonsai; 15th June 2010 at 06:35 PM.
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