Help on some Basic non Audio Circuit

Hi There,

I'm having some problems on a basic Encode/Decode circuit that i want to use as RF Remote.
It's based on the famous HT12E and HT12D IC as most people have used for this.
I'll be using it with RF Transmitter and Reciever based on Aurel's TX-SAW-MID 3V and RX-MID-3V.

But for testing things out i just builded the thing on basic blocks using only one switch and driving only one Led on the Receiver side and a wire from the DATA IN/OUT.
And while this one works no prob when using same PSU, it doesn't when separating these and having separate PSU's (still using Wire to connect Data IN/OUT, and same adress etc...)
And obviously doesn't wrok neither when using the RF TX/RX modules...

Attached is the Simple Schematic of it all, maybe i'm missing something, but i don't get why i don't have it when all driven with same PSU...

Thanks for any clarifications.

> using Wire to connect Data IN/OUT

One wire is not a connection (not a Circuit).

You probably have to connect both grounds together to complete the loop.

When on the same supply, the grounds are connected. When on two power supplies, you may have to add the common wire.

Hi PRR

I understand but the purpose of it is to have it as a wireless remote controller, so....

You already tried to vary the Rosc values (decrease R4 or increase R1) ? With your at the low end 3.xVDC supply the resulting frequencies vary a lot, so this might matter. Just an idea.

I ask on the EEVBLOG as well.
I had one Pin on the RX side (ENABLE) that had to be connected to GND.
What got me confused is the "Common" wiring etc... when directly connecting DATA IN/OUT then it needs
GND connected, but not in RF etc... anyway

I was able to make the circuit work on RF on Breadboard, but signal is not good
obviously a poor Grounding etc... Next step just build a Proto board.
The OSC resistors are taken from Datasheet.


T.

zayance said:

The OSC resistors are taken from Datasheet.

Click to expand...

..for 5Vdd.

True.

I think i've tried 750K and 27K as well, both were working when on Single PSU.
But this one works as is now, Tricky part is the RF and Ground plane etc...

All works ok.

I wanted to etch a board, but ended just using a Veroboard, my Dremel is dead for precision work,
used it on other stuff and now the axis is wiggling a lot, anyway, i tought the PCB would have been a msut for this, but
the control works no prob, at least for 20 to 30m distance with walls and all, seem to be doing its job.

You live you learn.


T.