GS-USB-PRO Sneak preview

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Steven Sesselmann
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GS-USB-PRO Sneak preview

Post by Steven Sesselmann » 04 Oct 2018, 08:29

Hi All,

After several weeks of intensive R&D, I finally have a product I am happy with... :)

Here is the all in one unit that simply connects to USB and detector and works with minimum adjustment. As promised this unit features smooth voltage adjustment, volume adjustment, pulse length adjustment, and a combination TRS/TRRS jack that will take a normal mono jack as well as the four ring iPhone headset jack.

The unit will come with SHV connector as standard and BNC for the signal port, a dip switch under the box selects between single and two wire detectors.

The pictured prototype unit is hand soldered, but once it has peen put through all the tests, I will order a small batch with the SMD parts machine placed and soldered.

I already have a couple of small improvements I want to add before releasing the final product, so stay posted.

Steven
GSV1.6.jpg
GS-PRO-USB V1.6
Steven Sesselmann | Sydney | Australia | gammaspectacular.com | groundpotential.org | rephopper.com | beejewel.com.au |

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pilgrim
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Re: GS-USB-PRO Sneak preview

Post by pilgrim » 06 Oct 2018, 16:04

Steven,
excellent work!
Could it be possible to insert a voltage self-regulation system in the driver?
Namely, when I connect the load, after a short transient, the voltage returns to the indicated value without load.
Daniel, Italy

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iRad
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Re: GS-USB-PRO Sneak preview

Post by iRad » 06 Oct 2018, 21:10

Steven - Great looking product with nice connectivity. Can you reveal voltage range/power info and USB audio specs (eg. bit rate and resolution, S/N ratio, DAC). Fantastic so far! Tom
Please check out my eBay Store: http://stores.ebay.com/The-Rad-Lab
Cheers, Tom Hall

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Steven Sesselmann
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Re: GS-USB-PRO Sneak preview

Post by Steven Sesselmann » 07 Oct 2018, 15:34

Daniel, the new GS-USB-PRO has a high precision voltage reference (MCP1541) and regulator to maintain a stable voltage throughout a relatively large temperature change.

Tom, I just did some measurements on the SNR (Signal to Noise Ratio). With the unit connected to USB, and voltage set to 1000V and connected to a 1 meter terminated SHV cable, I ran a recording with Audacity (see image attached). If we arbitrarily assign an average signal value of 0.5 (50%), then the SNR is 0.5/0.0001 = 5000 = 20log10(5000) = 73.97 dB
SNR.jpg
Signal to Noise ratio
Regarding the sample rate I use a Texas Instruments PCM2900C Codec, this chip samples at 48 kHz, but for some reason I can't explain, it seems to give better resolution when I select higher sample rates on the software side. I shall attach some images to show what I mean. http://www.ti.com/lit/ds/symlink/pcm2900c.pdf
Sample Rate Comparison.jpg
Sample Rate Comparison
Finally here is a Thorium spectrum recorded with the GS-PRO-USB and my now famous 2" CsI(Tl) Luuk/Tom detector.....not too shabby if I may say so myself :)
Thorium-CsI(Tl).jpg
Thorium Mantle Gamma Spectrum
Steven Sesselmann | Sydney | Australia | gammaspectacular.com | groundpotential.org | rephopper.com | beejewel.com.au |

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gianlu383
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Re: GS-USB-PRO Sneak preview

Post by gianlu383 » 09 Oct 2018, 08:32

hi steven,
what about .... object of desire.
congratulations, very versatile product.
Gianluca

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iRad
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Re: GS-USB-PRO Sneak preview

Post by iRad » 09 Oct 2018, 09:15

Steve - Looks great and that is normal behavior for setting of sample rate. Cheers, Tom
Please check out my eBay Store: http://stores.ebay.com/The-Rad-Lab
Cheers, Tom Hall

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Steven Sesselmann
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Re: GS-USB-PRO Sneak preview

Post by Steven Sesselmann » 09 Oct 2018, 12:53

Okay, I couldn't resist making one more little enhancement to the board, so it's going to be another couple of weeks...

I think I found a way to piggyback two units together without modification, just using a stereo crossover cable.

Cool if it works..

Steven
GS-PRO-USB-Path-1200x800-1.jpg
GS-USB-PRO
GS-PRO-USB-Path-1200x800-1.jpg (83.3 KiB) Viewed 2544 times
Steven Sesselmann | Sydney | Australia | gammaspectacular.com | groundpotential.org | rephopper.com | beejewel.com.au |

pietkuip
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Re: GS-USB-PRO Sneak preview

Post by pietkuip » 27 Oct 2018, 20:03

Just to ask if I understand the coincidence feature properly. So the USB connection is connected to an audio ADC circuit which has two channels for stereo. The new device has 3.5 mm connector that can accept an audio input signal for the other channel. That signal could come from a different kind of source, for example from a GS-1100 etcetera. Is that correct?

Yes, the direct internal connection may achieve lower noise levels than when it is tied to the computer input. I think we should order at least two.
Pieter Kuiper, Växjö (Sweden)
Course lab: 3 mCi neutron source; five 3" NaI(Tl) detectors, CdZnTe detector (Amptek); lead bricks, two GDM 20

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Steven Sesselmann
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Re: GS-USB-PRO Sneak preview

Post by Steven Sesselmann » 28 Oct 2018, 14:07

Pieter,

That's correct, the board has a stereo codec, I initially intended to use the left channel input only and terminate the right channel, but then I realised it would be impossible to do coincidence counting.

I thought about adding another jack plug with right channel input, but I wouldn't have been able to fit another jack on that side of the board, but as it turned out, the right channel (second ring on the jack) which is normally the right channel input anyway wasn't being used, so why not hook it up to the CODEC.

So now the single TRRS jack on the board is a multi function port, Tip is analogue output like the original GS, second ring is Right channel input, third ring analogue out for iPhone headset jack, and fourth ring is ground.

So you can use a simple GS-1100A or PRO as the driver for the right channel detector and connect it to the new GS-USB-PRO with a stereo crossover cable, which is basically a regular stereo to stereo jack with the signal wires crossed (I can make it).

Steven
Steven Sesselmann | Sydney | Australia | gammaspectacular.com | groundpotential.org | rephopper.com | beejewel.com.au |

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