Convert from 0 - 5V (DC) to 0 - 10 V (DC). (And filtering PWM; or using DAC)

Hi,

I'm helping a (spanish forum) guy to build a programmed contrifugal machine. I've got three questions:

1/ Can I get a "serious" continuous DC signal (see "2/" below) from an arduino PWM output (a R-C filter, for instance).

2/ What's the simplest way to get a 0 - 10 V. (to send to a frequency AM motor speed controller) from that (see "1/") 0 - 5 V continuous DC voltage.

3/ Would it be more practical to use the "due" DAC (for instance) than the PWM.

(These are more electronics questions than coding ones. I'm more concerned with ripple and impedances than the coding of PWM/DAC)

Thanks in advance.

Regards.

2/ What's the simplest way to get a 0 - 10 V. (to send to a frequency AM motor speed controller) from that (see "1/") 0 - 5 V continuous DC voltage.

To clarify: I wonder if there exists a "special purpose" card/module for this, that has a single (220 V AC / Arduino DC) supply. I know how to make it using a simmetrical powered OA based circuit 8), but I'd like using a "pret a porter" solution :|.

Regards

vffgaston: To clarify: I wonder if there exists a "special purpose" card/module for this, that has a single (220 V AC / Arduino DC) supply. I know how to make it using a simmetrical powered OA based circuit 8), but I'd like using a "pret a porter" solution :|.

OK, now you have lost me.

10V analog output implies an op-amp circuit powered from the 10V supply which incorporates a gain of 2 and a low-pass filter. Low-pass filter circuits are pretty easy to find, and the gain will be set somewhere along the way.

Now, whatever a "frequency AM motor speed controller" is, I don't know, but unless it uses complete switchmode circuitry (incorporating inductors), I would suspect it is in fact, generating a PWM output and you would be just as well off to use a basic switching circuit driven by the PWM you already have.

{In other words it is just plain crazy to filter PWM into an analog level to feed into another circuit to make it PWM again.}

The Arduino PWM frequency is only 500 Hz, and it has a pretty low output current anyway so trying to use a filter is unlikely to yield a true analog signal like you want. Now I don't know what you mean by AM motor speed controller... I mean it sounds like it could be a real thing, but it sounds like something you'd only use if you were controlling a turboencabulator. Here are some options:

1 - Use an MCU with a DAC And then use an external operational amplifier to multiply it by 2 2 - Use an external DAC And then use an external operational amplifier, or try to find a DAC that can handle a 10V power supply 3 - Use a frequency to voltage converter Most should be able to take a 10V power supply so you won't have to convert, this would be the most difficult to implement solution but it would also be the most fun

First of all, thank you very much to you two (Paul & Unit). Belive me if I say that some times I do regret not being a native english; I'm pretty sure I'm missing some subtleties (Is this correct?).

A AM motor speed controller... sounds really frightening :sweat_smile:. it is just an . . . . .. AC drive. (Maybe the heat wave in Spain -38 ºC outside- has something to do).

The AC drive the guy is using has an input that ranges from 0 (stop) to 10 V (full speed). For the moment I have suggested him to solve the problems one by one: to get it working in "manual" position and, then, controlling the whole system by means of the arduino. The "automatic cycle" he intends is pretty much like an old washer machine one: clockwise slow, counterclockwise slow, then medium, then centrifugate, . . . ., so I've told him to concentrate in the hardware first as the code is not going to be (I guess) difficult.

I've been working with a "due", so one possibility is to use one of the DAC's to generate a "quasi-continuous" signal (as Unit suggests). The other possibility I asked to myself (and to the forum) was to filter a PWM to get 0 - 5 V (The DAC the due uses spans 4/6th of the 3.3 V: 0.55 to 2.75 V).

Then the matter of doubling the range: I have a nice experience on electronics . . . that hasn't been renewed from the '80s!! (except for what I've read in the -this- forum along the last year). Although a lot of the, say, "discrete components" electronics (I include in this concept op amps, the ethernal 555, small TTL & CMOS circuits, . . . ) keeps being the same (much cheaper), I feel confused sometimes (I find nowadays things like 3.3 to 5.0 V level shifters -yes, I know they ARE NOT for continuous signals- that didn't exist then . . . ). For that -doubling the signal- purpose I'd have designed in the past a simple op amp (uA 741) circuit with a simmetrical (+- 12 - 15 V) supply to convert from 5 - 0 V (inverting "by software" in the arduino) to a 0 - 10 V. I'd need a double power supply and I remember adding caps (as the Texas Instruments handbook instructed to do) to make it stable for a continuous signal . . . . It needs a bit of soldering & skills that my "pupil" has not. That's what I asked for a "prêt a porter" solution . . . . .

(I hope having overcome the heatstroke and explained myself this time . . . . :sweat_smile:.)

Thanks again

turboencabulator

:stuck_out_tongue_closed_eyes: :stuck_out_tongue_closed_eyes: :stuck_out_tongue_closed_eyes: :stuck_out_tongue_closed_eyes: I’ll write it down!!. It’s brilliant!! :stuck_out_tongue_closed_eyes: :stuck_out_tongue_closed_eyes: :stuck_out_tongue_closed_eyes: :stuck_out_tongue_closed_eyes:

Okay, I didn't know the Due's DAC was that useless.

Now I highly doubt you're getting a "prêt a porter" solution here. There's no shield, breakout, through hole DIP, or anything of the sort that will take 5V PWM and convert it to an appropriate 0V-10V analog signal.

Unless someone makes it for you/your associate you're going to have to at least do something. Now it seems there will be a lot of vibrations on this thing so it can't be breadboarded forever. Yet supposedly there can't be soldering...

So what are you looking for, here?

Thanks again,

So what are you looking for, here?

Probably the confirmation that I have to make a small design (and, actually, it is not a waste of time). I'll post the scheme before building it.

(The electrical / electronics part is going to be rough enough. You can have a look on the thread "Ayuda Arduino + Variador de Velocidad Trifasico 220v" -Sorry I don't know how to post the real link-; pictures and photos are clear. Probably the op amp circuit will be mounted on a piggy proto card inside the cabinet).

Thanks again.

Regards.

(. . . . turboencabulator . . . ¡great!) :stuck_out_tongue_closed_eyes: :stuck_out_tongue_closed_eyes: