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.