Help with pcb description on a projection clock

Thread Starter


Joined Oct 24, 2016
Hey guys,
I'm new here and at the electronics world. But I understand a little!

I just found an old projection clock here in my messy place and opened it to see if the projector and the radio clock were separated things. I found that the only connection between both is 1.5, L+, L- and G. So I would like throw the radio away and keep the projector with a new power supply. The projector clock and the radio clock work separately, you need to change time on each one at a time and there's nothing that you can set on the radio clock to show on the projector clock. The projector has it's own setting buttons. But my doubts are:

1 - Does 1.5 and G mean 1.5V + and -? Could I connect to a 1.5V battery and test it?
2 - What does L+ and L- mean?

Here are pictures of the PCB connection and the clock model (what's in my hand is the projection unit.

Thank you very much for your help! Hope someone can help me =)

IMG_7709.JPG FullSizeRender.jpg


Joined Feb 5, 2010
Plus and minus with an added G.

Sounds like AC power. Look for diodes and a capacitor nearby. (Follow the traces on the board)


Joined Jul 13, 2015
You are right the 1.5 and G is look like a battery dc 1.5v (plus) and G(minus).
While L+ and L- is look a like a signal input line + and line - .
A signal is like a video or a pictures, to be input there, and it will projected as an output to the wall.

Thread Starter


Joined Oct 24, 2016
No idea. Why don't you measure the voltages on those connections.
Thanks for the simple idea! hahaha
The 1.5 and G are 1.5V clock power, while the L+ and L- are the LED 3.0V power.
I managed to plug 2 AA batteries to the L+L- and 1 AA battery to the 1.5/G.
I tried each separately and plugging L+L- I saw just 88:88 numbers. When I connected the other, the time appeared!

No I'll finish the soldering and mounting and will have a small projection clock!

Where is that flexible ribbon cable going?
The flexible cable is the connection between the board of the projection part and the clock LCD

Thank you guys!