HISTORY:
Another module from one of my storage boxes, pretty sure this is NEW but never been "put to the test". It was packed in a plain white box, now discarded.
This module is offered for the 'experimenter' and it could very well be perfect for a voltage or current measurement/indication display
HUANENG - Display module
No doubt it is made in China, I have seen a lot of manufacturers churn out these little modules in days gone by
Model: 3515
RED LED
3.5 Digit display
Nice bright display, easy to read even in full daylight (no backlighting required!)
+5V rail operation
Self zero function
Appears to be a 2 Volt DC model (based on the part number marked at the rear)
Complete display unit, LED display - drivers - input electronics
LSI chip (40 pins and in a socket)
74HCT044 (HEX inverter)
TO92 device but I cannot make out the part number ... TLx1AA, I suspect a FET transistor
Ribbon cable connects to an 8 way molex female connector
Some of the functions of the wires are unknown to me and I seem to have no instruction/user sheet for this module
Also very interesting is that right down one side of the LSI chip there are PCB pins which can be externally accessed but the purpose of those pins is not indicated
It is easy to identify the voltage measurement pin (marked)
I have not adjusted the trim pot near the transistor but it appears some sort of adjustments can be made with this, perhaps the zero null setting.
Identification of the module is a bit sparse ...
On the PCB
HUANENG 3515
On the White label stuck onto the LSI device
(diagram of the principal wires and their purpose e.g supply rails and input)
INPUT DC2V
PONER IN DC5V (Is that Chinese for POWER IN?)
Screen printed PCB has 3x wires connected which are marked as simply JP1, JP2 & JP3 - I have no idea of their purpose
The row of 20 PCB pins next to the LSI (spaced at 2.54mm) have absolutely no markings indicating their purpose.
DIMENSIONS:
External: 77mm wide x 43mm height x 24mm deep
Flange around the window (so that the module fits into a cutout on a panel): 4mm wide on all sides
Display viewing window: 51.5mm wide x 24mm height
TESTING:
Not a lot of information to work with but I undertook basic tests ...
Applied +5V and it comes alive! Takes around .5 seconds to settle down and sit on zero
Applied a varying low voltage (sub 1 Volt) to the wire marked as input and the display does indicate that the module can "see" the input. It seems to update the reading every half second or so.
I do not wish to spend more time on this module, that is something the new owner can do!
My basic tests stop here ... at least it powers up and can read the input signal!
COSMETIC CONDITION:
NEW
Old Stock
CLEAN
NO damage to the module or ribbon cable, molex type connector
Front display window is not damaged
I have now packed this module safely away in a sealed clear plastic packet within ESD packaging.
