As I work on my carrier current
coupler, there is another circuit
board that is sitting nearby on the
bench.
It is my version of Carl Blare's
BIG TALKER, the 13.560 MHz transmitter.
As I work on my carrier current
coupler, there is another circuit
board that is sitting nearby on the
bench.
It is my version of Carl Blare's
BIG TALKER, the 13.560 MHz transmitter.
MY BIG TALKER has been almost done for
a while, and there is very little left
to do.
Here's my question, because I don't have
time to do the research. Maybe you guys
can point me in a direction.
My Big Talker isn't as complicated as Carl's,
and is going to run much lower power.
It has 4 modules.
Here's the deal, I want to run it off of a
12 volt supply.
1) The oscillator needs 1.5 to 3 volts.
2) The buffer works best at 7 volts.
3) The audio driver amp needs 9 volts.
All of the above are operational. But
4) The final RF amp, just needs to be checked
a few times and soldered and checked physically
again. Since it will be running a lot lower power
than Carl's final amp, I am thinking it will need
probably 3 or 4 volts. So I am trying to figure
how to get all those different voltages from
a 12 volt supply. I know this is elementary stuff =
I can figure this out. That's not the problem. I
just am really lacking time. Can you guys point
to a reference or provide any suggestions just to
save me a little time?
Thank you either way!
Bruce, W 60 HZ
A voltage divider using resistors will be dependent on the load of each circuit. It can be done but with no regulation..
Check these out as an example..
http://www.amazon.com/Coby-CA709-Regulated-Universal-Converter/dp/B00009W5QT/ref=pd_bxgy_e_text_y
These are rated to 800 mA. but there are units out there that go as far as 2000 mA. One for each circuit and mebby a resistor to tweek the voltage a little? At least you'll be in the ball park..
The only thing that I caution is ground loops between circuits from a central power supply. The grounds will not be isolated and that could cause issues..
Using a voltage divider to provide different voltages in a circuit can be problematic because the output voltage depends on the load current. An inexpensive way around this is to use the LM317 adjustable voltage IC data sheet link . The voltage can be set with two resistors or if desired with one resistor and a pot.
I either use the 317 or fixed voltage regulators in the 78XX series for this depending on whether the voltage needs to be adjustable or not.
Neil
Use the good ol 7809, 7805 and LM2937.
Using a variable regulator is problematic when the adjustment pot begins to get dirty and like a dirty volume control, that voltage will fluctuate and spike like the volume does passing through a dirty volume control.
Set voltage regulators are precise, cheap and also provide some internal filtering as well as isolation, and internal crowbar short circuit protection.
RFB