Gamma Spectrometry Forum

This post is probably of limited interest to the group in general, but it serves as a journal or benchmark for my hardware changes. Each time I manufacture a new batch of circuit boards I make a few hardware changes and improvements. I just started using GS-USB-PRO V3.2 and put the board through a series of tests, and it all tested good. So just for the record;

1) C5, C6, C7 & C23 replaced with SMD capacitors of the same value
2) C1, C2, C3, C4, C8, C9, C10, C11 Electrolytic caps replaced with SMD caps of the same value
3) C12 and C13 changed to 30 pF for more reliable USB connection.
4) Three mounting holes added for optional Schmitt trigger conversion (neutron detectors)
5) Power to opamp (pin 5) changed from 3.3V to 5V (slightly improved linearity at top end)

These are very minor changes and no one should notice the difference, except me, as there is a bit less hand soldering.

Steven

Nice changes. Just thinking, for those people using faster scintillation mediums a TLV320ADC5140 capable of 768Khz sampling might be something to look into? CLK input would be ~36.8Mhz
I like your product and small changes. It keeps evolving :)

Conor,

Yes, small changes at the time, like natural evolution, I make mistakes and discover improvements :)

I am aware of the faster ADC's, but unless I am mistaken, the chip I use is the only one with built in USB connectivity. Switching to a fast ADC means more digital circuitry and some kind of micro to handle the USB, that will require quite a bit more R&D.

For 99% of users their detectors are the weakest link, not the spectrometer or the sample rate. Only a few specific experiments require faster sampling.

Steven

Steven - Ever look at any 192KHz/ 32bit single chip solutions from Cmedia? Like the CM6642 for instance...
https://www.cmedia.com.tw/products/USB20_HIGH_SPEED

Thanks Tom,

Never come across that chip before, it looks interesting, might be a suitable upgrade. Shall study study the pin out and if suitable get some sample chips to play with. makes it a lot easier if it has the USB functionality built in.

Steven