Re: Variable power control


Diver Martin <diver.martin@...>
 

If I need a true DAC output, I'll sometimes throw on a $2 MCP4921.  Depends on if you need i2c or SPI though.  There's a bajillion single chip / single output DAC's out there in the wild.

On Mon, Jan 1, 2018 at 8:50 PM, Clark Martin <kk6isp@...> wrote:
The Nano and other AVR Mega based MCUs do not have DAC outputs.  The AnalogWrite function sets a PWM.  So that pin is switching between 0 and 5V with an average value proportional to the programmed value.  It can be filtered to produce a DC signal.  But it might require a lot of filtering, and the size of the caps might get big depending on what frequency is being used.

I’ve been thinking about using a Micro Chip MCP4725.  It’s a 12 bit DAC interfaced with I2C.  This would give you a nice DC signal with very low parts count.

Clark Martin
KK6ISP

On Jan 1, 2018, at 7:27 PM, Ghericoan <boakawizkid@...> wrote:

Take a look at this, http://www.toptechboy.com/arduino/lesson-8-writing-analog-voltages-in-arduino/

I am trying to figure out a way to use this inline with the PA power supply to be able to control the output power from software. Just brainstorming, but if you had a spare pwm pin and buffered its output with some capacitors into a transistor controlling the power rail, it might be doable. But I am really new to all this and am just looking at projects to try when my kit comes in.

Someone feel free to poke a hole in this and save me from wasting an afternoon if this isn't on the right track for a software controlled solution...





--
Martin Held - AE7EU
http://ae7eu.com/
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