Author Topic: Handheld Precision Digital Voltage Source - IanJohnston.com  (Read 1760 times)

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Offline IanJ

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Handheld Precision Digital Voltage Source - IanJohnston.com
« on: January 09, 2016, 02:48:07 AM »
Hi all,

Finally!!!.......I've built up a first batch of my Handheld Precision Digital Voltage Source's and are available to purchase via my online shop.

http://www.ianjohnston.com/index.php/onlineshop

A big thanks to Dave for giving me the push I needed to go into production after featuring one of my early prototypes in his Mailbag Monday a couple months ago.

I've made quite a few changes since the mailbag and have addressed a few niggles Dave commented on, i.e.

- Better stability
- Less noise on output
- Better quality banana sockets
- More intuitive user interface
- Internal sense line to banana's allowing heavier loads without compromising output voltage accuracy
- Coax ditched in favour of heavy gauge wire
- MAX6350 Vref ditched in favour of an LM399AH = much better stability and tempco.

Below is a photo of the production unit, any questions please ask via the contact form on my site:-
http://www.ianjohnston.com/index.php/contact

FUNCTIONS & FEATURES:-

- 50mV to 10Vdc user adjustable output (4d.p’s, 5d.p’s extended, i.e. 10’s of uV’s).
- Voltage setting or ramp up/down controls via the 12 button numeric keypad.
- Soft power switch.
- Based on the industry standard LM399AH voltage reference.
- No potentiometers inside or outside.
- 18bit DAC with an accuracy/stability down in the tens of uV’s (using a PLC filter of 1.0 or higher).
- Battery voltage monitor, including low voltage warning and auto-shutdown.
- Output voltage monitor including overload / short circuit protection.
- 3” Graphics LCD (128x64 pixels).
- Atmel 328P micro-controller (uses Arduino bootloader).
- Precision chopper op-amp on final output with extra stability achieved using low tempco resistors.
- Re-calibration by the user possible via keypad/LCD and saved to flash rom.
- Battery powered.
- Battery reverse polarity protection.
- Quality Hammond 1599 case.
- Quality aluminium anodized & engraved front panel.
- Quality 4mm banana sockets.
- Single PCB integrating the analog & digital electronics, LCD, keypad & battery terminals.
- Printed manual including factory calibration/settings record supplied. Unique serial number.

Ian.
www.ianjohnston.com

 
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Online Vgkid

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Re: Handheld Precision Digital Voltage Source - IanJohnston.com
« Reply #1 on: January 09, 2016, 08:44:08 AM »
You have done a really nice job on it.
If you own any North Hills Electronics gear, message me.
 

Offline PedroDaGr8

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Re: Handheld Precision Digital Voltage Source - IanJohnston.com
« Reply #2 on: January 09, 2016, 11:14:13 AM »
Well outside of my hobbyist budget but a DAMN nice looking device!
The very existence of flamethrowers proves that some time, somewhere, someone said to themselves, "You know, I want to set those people over there on fire, but I'm just not close enough to get the job done." -George Carlin
 

Offline HKJ

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Re: Handheld Precision Digital Voltage Source - IanJohnston.com
« Reply #3 on: January 13, 2016, 06:47:31 PM »
Nice job, but I would have liked an encoder in addition to the keyboard.
And why the big margin (100mV) before it warns about output "out of tolerance"?
 

Offline babysitter

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Re: Handheld Precision Digital Voltage Source - IanJohnston.com
« Reply #4 on: January 13, 2016, 07:43:49 PM »
Looks good - do you want some reviews? :)

What I miss is a programmable "true" zero volt output.


I'm not a feature, I'm a bug! ARC DG3HDA
 

Offline HKJ

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Re: Handheld Precision Digital Voltage Source - IanJohnston.com
« Reply #5 on: January 16, 2016, 06:38:40 AM »
Fast shipping, I received mine today.

The calibration looks good, my two best DMM's show x.0000yy (in a few cases z.9999yy) when checking the different full voltage steps. This check was done after more than one hour with power and ACAL on the DMM's/you unit (DMM's: Keysight 34470A and Keithley DMM7510). I will probably not bother doing my own calibration.
This was exactly what I hoped for, thank you.

But it would have been nice if you mailed the calibration certificate, now I will have to scan it (Paper manuals disappears rather fast).
 

Offline maukka

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