New version DSO138 - Modify your model!

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James
Posts: 2
Joined: Fri Sep 08, 2017 7:57 pm

New version DSO138 - Modify your model!

Post by James »


I would like to provide the manufacturer and also the users of DSO138 this improved schematic of DSO138. This includes all changes which I as a professional power supply engineer recommend to do for maximal efect in:



- Reducing noise

- Trace stability

- Minimise input distortion

- Power capability from +5V & +12V PC supply


This improvement provides you to use DSO138 up to 100kHz in correct voltage course displaying and up to 220kHz in frequency measurement. I think that's the best you can get from this board with ARM CORTEX M3 and hope the construction is clear from attachment. If you have any questions I'll be pleased to answer them. :)

Here are requied fotos - preview of final design (this invention).
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Attachments
DSO138 schematic.png
DSO138A.JPG
DSO138B.JPG
davef
Posts: 78
Joined: Sat Jun 06, 2015 10:01 am

Re: New version DSO138 - Modify your model!

Post by davef »

Appear to be sound modifications.

Did you find the sub-standard "TL084" by testing its slewrate?

I assume you are using the latest firmware, correct?

Thanks for providing the schematic and photos.

davef
jye1
Posts: 1221
Joined: Wed Feb 20, 2013 4:58 pm

Re: New version DSO138 - Modify your model!

Post by jye1 »

Thank you very much James! It is great. We really appreciate your suggestions although we might not implement it to the existing mode because we have a new model - DSO138min to be released very soon.
James
Posts: 2
Joined: Fri Sep 08, 2017 7:57 pm

Re: New version DSO138 - Modify your model!

Post by James »


Yes, I'm using software version *-060 which has all functions of the osciloscope.

The TL084 input amplifier quality is best visible when you look at the DSO138's comparator output on higher input frequency with a faster osciloscope. If the square shape changes to triangle and the amplitude goes down it means the OpAmp is not fast enough. Now you can measure the real slewrate of the amplifier used. Slow comparator usually causes a desynchronisation of the course on the screen.


Here are fotos showing this construction in use: The largest noise is on 100mV range, other ranges noise is smaller. I think it's great resault with so simple HW ;)

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Attachments
DSO138C.JPG
DSO138D.JPG
newsonr
Posts: 1
Joined: Sat Jan 27, 2018 1:01 am

Re: New version DSO138 - Modify your model!

Post by newsonr »

Hi,
I would like to try your mods but can't make out the attachments!

R Newson
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