开云体育

Here's an idea for anyone who is into hardware hacking their NanoVNA (like me).
You can now switch out that diode at D2 (for the battery indicator) and put in a 10X
attenuator on pin 1 (VBAT) of the microprocessor.
Connect to an external jack and you now have a VNA/pseudo-Voltmeter combo !!
You should be able to measure most things above 1 volt to over 12V - good in a pinch
if you're up the tower and need to measure

You'll need to reference the schematic and the mod is not for the faint of heart but
you need 4 parts - 2 resistors (for the 10x atten), a Schottky diode (for reverse prot) and a 5.4V zener (over volt prot).

To do this, you need to use DMR's latest firmware: Vbat_vf_EDelay_50ohM_DFU.dfu
It's on the forum - search out his posts on Oct 10, 2019

Now all we need is a voltmeter-only display mode ...

Cheers,
Larry

Interesting...However a search on DMR did not result in any hits for the October 10th.

Herb

Sorry, there was a small bug in the firmware. The corrected version is here.
Output voltage Li-ion battery, and velocity factor.

On Fri, Oct 11, 2019 at 02:34 PM, DMR wrote:

Sorry, there was a small bug in the firmware. The corrected version is here.
Output voltage Li-ion battery, and velocity factor.

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Awesome!
I'm going to have to do like Kurt and order another unit just so I can play around with some of the experimental firmware that has started to appear. Hopefully your changes will make into the master release.

Herb

Where can I find a description of the actual hardware modification (resistor placement and values) for the on-display voltage measurement?

Herb

No resistors are required, a diode with a voltage drop of 600, 620 millivolts must be installed. Since the D2 diode has already been installed, no modifications are needed.
I thought it necessary to add a battery voltmeter, as I want to see more accurate information.
The firmware is based on the latest changes of the edy555. Also, it has a virtual keyboard that does not hang, + meter measurement to hundredths of a meter when measuring short cables.

Double awesome DMR! Just ordered another NanoVNA-H and can't wait to try your firmware.

- Herb

Hi DMR

I have just installed your amazing firmware! Works well, but when i press 'save'
in the config area, and then switch off / on, it shows the version and hangs...
Then need to re-install.
Cheers
Colin

Hi colin.jaguar999
Sew the Clear Memory firmware first, and then the desired one.

Ok, I'll do that, Thanks
Cheers
Colin

DMR
This firmware seems more responsive on the keyboard and switch, but still cannot get it to 'save' correctly; Tried loading the Clear Memory firmware first few times also the other versions of it as well. Everything else is working very well. Thanks.
Like the blue colouring ...

Try to save 2 times in a row.
I use this firmware on my two devices, it is used by my friend, there are no problems. Perhaps you are not using a reset during calibration.