Guys, i need a help with something.
I need to make a test rig.
The input is 24V.
I need 3x adjustable output voltage ranging from -10V to +10V <1A
Can you guys please suggest some solution??
Thanks for any help.
I already responded to you in the project forum.
24 v AC or DC?
DC.
Ill say differently.
i need potentiometer that output from negative 10v to positive 10v in linear fashion.
+- 12v but not adjustable here:
http://www.jameco.com/Jameco/catalogs/c111/P146.pdf
Please do not double post.
Sorry LarryD, i`m unable to remove the other post.
Im still not sure if you follow what im after.sorry if i`m not making it clear.
See,bipolar supply is not a problem it self as as you show to us it can be bought,
But making output in linear fashion from negative to positive is problem here.
I need something that will switch automatically from negative to positive when 0V is reached and opposite from positive to negative.
Do a Google search on:
dual dc to dc converter adjustable images
Then pick one of the images and visit their site.
You have three problems:
-
Most potentiometers are not rated for 1A
-
You have 24v, but you need a range of 20v.
Considering both problems, you're probably better off adjusting the pot that controls the output voltage on your DC-DC converter.
- You need not 0v to +20v, but -10v to +10v. Does this need to be referenced to the same ground as the 24v supply? If not, you can provide +10v and +20v, and call the +10v ground (be careful if you do this that you're not elsewhere assuming that they're the same). But if the +24v and +/-10v both need to be referenced to the same ground, you need an inverting dc-dc converter - although these are not harder to make, they're much less common as assembled modules on ebay/etc, since the demand for them is probably around 2 orders of magnitude lower.
Drazzy, the 24v input and +-10 will need to have common ground.
As i said before, supply is one part, i think this wont be a problem, the other part, switching from +/- and -/+ makes me confused on how to do it it.
its a must to have that pot to the max left gives -10v middle position is 0v max to the right is +10 and all the values in between are also important.
Please ignore pot rating
DC.
Ill say differently.
i need potentiometer that output from negative 10v to positive 10v in linear fashion.
For a single output that adjusts between -10V and +10V, you essentially need an amplifier. i.e. An audio amplifier* that goes down to DC (zero Hz) and has an output swing of +/- 10V. 10V @ 1A is 10 Watts, so you'll need an amplifier rated for at least 10W. (And be aware that many amplifiers are "optimistically" rated, and if you use an amplifier chip you'll need to heatsink it.)
And, you'll still need the DC-DC converter because the amplifier will need bipolar supplies. And, you need a little more than +/-10V from power supplies because there is always some voltage loss in an amplifier circuit. (You already have more than +10V).
Then, you simply put a pot on the input connected to positive and negative voltages (with the wiper to the amp's input). If the amp has a voltage gain greater than 1, you'll need a voltage divider on the input.
...Once you have positive & negative voltages, it's easy to connect a pot that swings from negative to positive. But, you can only get a few milliamps from a pot.
- Most audio amplifiers have a capacitor at the input that prevents them from working down to DC (DC is not good for speakers and it's hard on the amplifier too
). But if you build an amplifier from an audio amplifier chip, it should be easy to modify the manufacturer's recommended design to work at DC.
Then you need a pair of DC-DC converters, one of which is inverting....
You can get around the current limit on the pot with an amplifier, or an opamp wired as voltage follower - the more current you need out, the harder this part becomes.
Did you change the title of the thread?
.
DVDdoug
For a single output that adjusts between -10V and +10V, you essentially need an amplifier.
any chance for some kind of schematic/part numbers??
LarryD
Did you change the title of the thread?
Yes i did.
Guys, current really dosn`t matter, I just actually need to put a signal voltage so the software can generate curve.
Guys, current really dosn`t matter, I just actually need to put a signal voltage so the software can generate curve.
A bipolar "signal" with little current can be from a pot with one end connected to a + voltage an the other end connected to a - voltage.
And, by this point you know how to get the negative voltage.
But if this for the Arduino, you can't put negative voltages or voltages greater than +5V into the Arduino.
But if this for the Arduino, you can't put negative voltages or voltages greater than +5V into the Arduino.
i have an old track measuring card that you fit into computer, with variety sensors ( 10 inputs) the software draw curve of how even,angle the road/track is.
I dont have the actuall measuring rig but i checked all before, and i remenber seeing opamp in the box and i think 74xx ic and 4029b as well. shame i dont have that to copy. hence all those questions, as originally i thought it will +5V only per input.
A bipolar "signal" with little current can be from a pot with one end connected to a + voltage an the other end connected to a - voltage.
so you telling me that if i take the +/-10V out of regulator and put -10V to leg "1", +10V to leg "2" that output will go from negative to positive without need of switching??
google "center tapped pot".
Hi,
Can you post a picture of this card and any part numbers, if it had sensors connected to it, and they were -10 to +10V then it may be possible that the card supplied the -10 and+10V.
Do you have a manual for the card, how do you know you need -10V to +10V input?
Tom.... 
Pictures please, and attach them to your post, don't post them off site please.
Your problem is not that easy to solve
First of all you need a negative voltage. Depending on how much milliAmperes you need there are several designs that work well. Just use Google for this part of your problem.
This answer is very unspecific, but there are too many solutions to this problem.
If it is just a few milliAmpers, the job will be easy. If you need 100 mA or more, it will not be that easy anymore.
I had the same problem as you lately - building a signal genarator (1Hz - 5MHz).
The signal generator is a XR2206. The output stage is a LH0002.
The LH0002 is no longer available, however there are replacement chips. I will not recommend any chips that I have never used myself.
HOwever, if the recommended replacement chip does the same jobe as the good old LH0002 you will have a perfect chip if you do not need more than 100 mA of output current.