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QuantAsylum QA400 and QA401
QuantAsylum QA400 and QA401
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Old 7th August 2016, 06:10 PM   #2081
jan.didden is offline jan.didden  Europe
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Yes when I am ready I can see if there is interest in a Group Buy. If I can get say 50 or so made that would make the price much more friendly!
Especially for the box and PCBs, and a few relatively expensive items like the AD536 AC-to-RMS converter.

Jan
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Old 7th August 2016, 06:11 PM   #2082
mkc is offline mkc  Denmark
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QuantAsylum QA400 and QA401
Hi Jan,

Looks very nice. Depending on price I would be interested. Although I have a Shibasoku 725C here awaiting to be hot-rodded "davada" style.

Cheers,
Mogens
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Old 7th August 2016, 06:20 PM   #2083
davada is offline davada  Canada
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Quote:
Originally Posted by jan.didden View Post
Yes when I am ready I can see if there is interest in a Group Buy. If I can get say 50 or so made that would make the price much more friendly!
Especially for the box and PCBs, and a few relatively expensive items like the AD536 AC-to-RMS converter.

Jan
You're getting the level of a sine waveform. Do you really need to use an RMS detector.
I'm not familiar with this particular pic.Most of them come with at least a 10bit ADC.
You can sample the peak of the sine and convert to equivalent RMS.
Even a cheap peak detector would work for this. Or generate a quadrature from the fundamental and zero crossing detector to trigger ADC.
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Old 7th August 2016, 06:32 PM   #2084
davada is offline davada  Canada
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Originally Posted by mkc View Post
Hi Jan,

Looks very nice. Depending on price I would be interested. Although I have a Shibasoku 725C here awaiting to be hot-rodded "davada" style.

Cheers,
Mogens
Buy a cache of op amps now because they could disappear in a year or so the way things are going.
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Old 7th August 2016, 06:48 PM   #2085
31697B is offline 31697B  Thailand
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Maybe a cheaper way would use a auto-scaling DVM IC and drive relays to affect input attenuator instead of the display. Or even cheaper would be an attenuator built around the multi-comparitors in the LM3914.


THx-RNMarsh

PIC16F688 Digital Voltmeter - Electronics-Lab

http://www.kitelectronica.com/2016/0...14-lm3915.html

Last edited by 31697B; 7th August 2016 at 06:51 PM.
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Old 7th August 2016, 06:55 PM   #2086
davada is offline davada  Canada
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Originally Posted by RNMarsh View Post
Maybe a cheaper way would use a auto-scaling DVM IC and drive relays to affect input attenuator instead of the display. Or even cheaper would be an attenuator built around the multi-comparitors in the LM3914.


THx-RNMarsh

PIC16F688 Digital Voltmeter - Electronics-Lab

Tutorial circuito integrado LM3914 LM3915. - Kits de electrónica y circuitos.
Interesting. One could add log function to get dBV.
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Old 8th August 2016, 03:30 AM   #2087
benb is offline benb  United States
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Originally Posted by jan.didden View Post
Yes, the numbers.
The max input is 100V RMS (140V peak) so you can directly measure power amp output. Min. input around 150mV. Between those levels the autoranger will deliver around 1V to your soundcard. Fully automatically.

Freq response is flat to 100 kHz at +/- 0.1dB. Distortion -120dB. That should be OK for all those sound cards out there.

To help with setup, the display shows the actual level going into the soundcard and the autoranger input level and attenuation or gain setting applied.
Atten/gain ranges from -40dB to +16dB.

Jan
Dare I ask how fast this thing switches between levels? What will a soundcard see if the input goes from 0V to a 140Vp 20KHz sinewave?
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Old 8th August 2016, 07:15 AM   #2088
jcga is offline jcga  France
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Hi Jan,

exactly what I was looking for !
Count on me for one piece...
Best
Jean Claude
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Old 8th August 2016, 07:27 AM   #2089
jan.didden is offline jan.didden  Europe
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Originally Posted by benb View Post
Dare I ask how fast this thing switches between levels? What will a soundcard see if the input goes from 0V to a 140Vp 20KHz sinewave?
Attenuation rate is about 100dB per second. But the output is limited to a safe value so such a step won't be a problem.

Jan
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Old 12th August 2016, 04:30 PM   #2090
Robbo67 is offline Robbo67  Australia
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Quote:
Originally Posted by jcga View Post
Hi Jan,

exactly what I was looking for !
Count on me for one piece...
Best
Jean Claude
Me too!
Just what I'm looking for to match my QA401
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