UNI-T UT61E Backlight

This is a backlight mod for the UNI-T UT61E based almost entirely on [Nisei]'s tutorial. It consists of a touch sensor board (without sensor pad) and a backlight board. I had intended on using an Atmel dedicated Qtouch IC but it's current draw was a lot higher than the TonTek version. I also intend on using the touch sensor board for other projects.

Backlight Board

The area where I wanted to put my backlight board into was measured and 3D modeled in SolidWorks.

Finalized backlight board layout. It's reversible if the light transmits better. R2 is a dummy to prevent teeter-tottering when flipped over. Solder pads either side for convenient wiring.

Here's a somewhat 1:1-ish layout.

And here's the board sitting pretty in it's new home.

Touch Board

Here's the near finalized layout for the touch board. I wanted this small and low power and usable for other things besides backlighting a meter. A resistor is inline with the transistor's output so that I can directly wire LED's or whatever to this design for a future project.









And a handy schematic ...



And here's the actual thing.

BOM (completely unofficial)

1. TonTek TTP-223-BA6 ... touch sensor IC
2. MCP1703 (5V) ... voltage regulator
3. MMBT3904-7-F ... trusty NPN transistor
4. LTST-S220KGKT ... teeny weeny side emitting green LED
5. These green 3mm LED's worked much better.

To-Do's

1. Experiment with touch sensor pad size.
2. Install pad.

To-Done's

1. 3d model bklt location
2. general component selection for brds
3. layout of touch brd
4. layout of bklt brd
5. checked fit of 1:1 bklt brd paper cutout in meter
6. ordered bklt brd
7. order LED's for testing
1. LTST-S220KGKT
8. order components ... oops, too soon.
9. finalize touch brd layout
10. order touch brd
11. Assemble and test bklt brd
12. Assemble and test touch brd