I am only using it to power the RX, so 2watts should be enough power. (40mA @ 12v ~ .48 watts)
But, I can only seem to find these smaller ones ISOLATED, which isn't good for my RX since the grounds have to be common..
could I just tie both grounds of the dc-dc converter together to make the grounds "un isolated"? I read that I could, (but that it defeats the point of an isolated converter) but I want to make sure that is correct?
What you should do, is to connect each ground to the ground point closest to the origin of the corresponding "active" wires, and keep each pair of wires - supply and ground - together. So your output wires from the isolated converter go together to the 433mhz TX (and the input wires, together direct to your 5V source).
This is very useful as it minimises the effect of transients in the ground wires.
Paul__B:
What you should do, is to connect each ground to the ground point closest to the origin of the corresponding "active" wires, and keep each pair of wires - supply and ground - together. So your output wires from the isolated converter go together to the 433mhz TX (and the input wires, together direct to your 5V source).
This is very useful as it minimises the effect of transients in the ground wires.
thanks for the response, but I am confused to it meaning.
my plan was to integrate this into a PCB... I plan to connect vcc to vin+ then connect vout+ to the vcc of the 433mhz module, using a short trace. then connect vin- and vout- to the ground plane. Are you saying down connect vout- to the ground plane until I get to the tx ground?
Qdeathstar:
I am powering around 20 LEDs, a 433mhz rx, and a tlc5940 on the same board, so keeping it at 5v is kind of useful...
I think you're using a 5volt/1A DC/DC converter (previous posts).
What is your raw supply voltage for that.
A TX could be supplied from that raw voltage, just like you would do with a relay.
A 433Mhz transmitter uses milliamps, and is probably not used very often.
So a small battery would be another option.
Leo..
on this board, I am using a 3a 5v wall wart that plugs into a printed PCB and provides power to the arduino and the other equipment. it's kind of like a shield for an arduino mega. I am currently using a large 5v to 12v dc dc converter, it works, but my idea was to make it smaller. I don't really like the battery idea, because that means I'll have to change it...
the board I am talking about now is the main control unit for my project, I also have another board that drives led strips, where I am going from 12v to 5v for a teensy, but that's not related to this board.
Qdeathstar:
Are you saying don't connect Vout- to the ground plane until I get to the tx ground?
As a general rule. But on a PCB, the distances are generally short and perhaps more to the point, the preference is to "flood fill" the ground plane so that resistance and inductance is really low anyway. If double sided, flood fill both where possible and provide plenty of vias.