Analog Output Voltage

greenman100 · 09-10-2007, 05:40 PM

We're designing a 4 output add-on board for the Fusion Brain.

We will offer 4 full-scale settings, adjustable in steps of 32. For example:

0-5vDC: steps of .16 vDC
0-12vDC: steps of .38 vDC

What 4 ranges would you liked to see?

Is 5 amps enough? Note: more than 5 amps SIGNIFICANTLY increases cost.

greenman100 · 09-14-2007, 10:00 AM

I guess no one is interested, good to know.

2k1Toaster · 09-22-2007, 09:52 PM

Is voltage output something you guys would like? I thought that controlling fan speeds and things like that was what people wanted?

Speak now or forever hold your peace.

doogieb · 10-03-2007, 05:15 PM

Hi there, I'm looking at potentially controlling fan speed and temperature in my car via the PC, similar to what is discussed in this thread

From what I can see, my 1990 BMW E32 730i uses variable resistors for the temperature and fan speed selection.

Is there a simple way to interface with this via the fusion brain with the digital outputs (I'm guessing deciding on the number of possible steps and building a resistor network which translates into these steps), or would it be achievable with this add on board, or is there something else obvious I'm missing?

2k1Toaster · 10-05-2007, 04:12 AM

Quote: Originally Posted by doogieb

Hi there, I'm looking at potentially controlling fan speed and temperature in my car via the PC, similar to what is discussed in this thread

From what I can see, my 1990 BMW E32 730i uses variable resistors for the temperature and fan speed selection.

Is there a simple way to interface with this via the fusion brain with the digital outputs (I'm guessing deciding on the number of possible steps and building a resistor network which translates into these steps), or would it be achievable with this add on board, or is there something else obvious I'm missing?

This is doable. You can create an R2/R network if you want, but you will need an amplifier in there too so that the value doesnt change depending on the load! It is pretty simple and something like a 741 should work. We will eventually have this board available for sale all together if you would rather purchase all together than build the analogue output yourself.

inh · 10-06-2007, 02:28 AM

i think analog outputs would be pretty cool. At the moment, I dont have a use for em, but you never know..

h3rk · 10-13-2007, 05:07 AM

Very interested in analog outs here, the obvious climate controls use was my main motivator, but this silly little CB project idea thread I started would probably use them as well. Is this going to be built with controlling a stepper-motor type of servo in mind as well? can you see a way, without a servo pot, to use analog output to vary a resistance setting in another circuit? Two hands up for analog out. Many vehicles control the heater's blend door with such a servo.
I think it would probably take more than 5A to replicate the lexus parallel park trick, wouldn't it? But I'm fine with starting small.
I really would like to see the analog out option made into a reality!

Digipot?

h3rk · 10-27-2007, 06:19 AM

How is analog output going to work for skinning and in the program? am I going to be able to use the signal going out for indication? as a percent? engineering units?

For instance, my fan speed indicator needs to know what's going out to the fan....
I guess I could just use a resistor network and a crap load of DO's but that would not be very cool.

h3rk · 10-28-2007, 10:39 PM

Is output voltage going to be adjustable or are you...that's the 4 range thing isn't it?
I can't think of anything other than 0 to 5 or 0 to 12 that I need, maybe 0 to -5 and 0 to -12?

5 amps isn't going to be enough to drive fans, so another amplifier will have to be put to use then.

How much money are you looking at for say a 40A version? I was looking to drive my blower motor with a R/2R DAC and an amp that I could adjust with pots for minimum fan speed and max fan speed, I figured that would make it so others could follow, and implement in their vehicles. If you made a high output version that would sure be nice.

What's the alternative to 10 (or whatever) speed fan control; 10 outputs and relays with possibly a separate brain. (Yuk! - So much for small electronics). All of those who want to have a smoother fan acceleration with your climate control use of the brain, feel free to chime in here, and show some demand. I guess it's all about the cost though.

I'm thinking that 40 amps enough to cover the range of most vehicles blower motors.

4 outputs and 32 steps? wow.

my digital math must be screwy, it happens.

Edit:Actually, I'd like to know how that works. Maybe I'm just missing something simple, but 1111=15 (16, including 0) and 11111=31 (32, including 0) steps. This would help me with my skinning.

greenman100 · 10-29-2007, 07:17 PM

1. If you want negative voltages, reverse polarity on the device
2. 5 amps is a lot... what would you drive that pulls more than 5 amps?
3. For a blower motor, I'd use a resistor block and relays. To do it in solid state would be expensive. Really expensive.
4. I was implying there would be four analog outputs on one PCB. Each analog output would take up two digital outputs - the brain would control the analog output in an up/down fashion. WIth sample rates over 30hz, it could go from zero to full scale in a second.

h3rk · 10-29-2007, 08:25 PM

Ok, that clears things up. Good deal with the 2 digital outputs. There has got to be a better way than using up 10 digital outs to control a fan in 10 speeds...

Re: Soild state fan motor driver- Like how expensive(ballpark)?

As far as the amps thing, I wasn't thinking of anything in particular, actually I thought I saw where you specified that, but looking back, I guess not. So how many amps are we looking at?

h3rk · 10-30-2007, 08:31 AM

Will we be able to also send specific values to the analog modules as well as sequential raise/lower commands. If not I hope we can get that effect in the software, and have the software give the requisite number of raise/lowers. That would be needed for slider type controls.
And will the modules be able to communicate current value so the software could know "where" it is at? That might be needed to accomplich the above, as well as be useful feedback to the user on the interface.

greenman100 · 10-30-2007, 01:19 PM

Quote: Originally Posted by h3rk

Will we be able to also send specific values to the analog modules as well as sequential raise/lower commands. If not I hope we can get that effect in the software, and have the software give the requisite number of raise/lowers. That would be needed for slider type controls.
And will the modules be able to communicate current value so the software could know "where" it is at? That might be needed to accomplich the above, as well as be useful feedback to the user on the interface.

Yes. The module will use an analog input as a form of closed loop feedback.

h3rk · 11-10-2007, 12:27 PM

Any new, or final, word on what the output specs on this thing are going to be?

mx270a · 03-03-2008, 04:12 PM

I just got really interested in this. I'm working on software that will steer a tractor. The steering system is electric over hydraulic, so I need to be able to control that valve. It seems that the particular valve I will be using has one electrical input of variable voltage to sense what to do. The simple way to connect it would be to just use a potentiometer. At 50% of the system voltage, it is neutral. Either side of 50% causes it to turn the wheels. Min/Max is at 25% and 75% of system voltage. The amperage requirement is extremely low - less than 1 mA.

So am I just looking for a digital potentiometer?

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