Maybe TOO simple ?

[KermitDK]

Hi,
I am really stuck (or tired) :

I have a 0 to 10 V DC signal, and I need to convert it to a -5V to +5V signal.

Any ideas ?

Br

Claus

[Pack34]

What available power rails do you have?

[Andy Watson]

Need some more information - like what is the source of your signal and what is it destined to drive. A quick and dirty solution would be to stand the signal source ground on a reference of -5V - but we would need to know more details to determine if this is an acceptable solution.

[uncle_bob]

Hi

As mentioned before, we're making guesses on to little info.

Wire up an op-amp with a +/- 12 V supply. Feed the 0 to 10 into one input. Bias the other at 5V with a pair of resistors. The output will swing +/- 12V. Attenuate it to +/-5 with another pair of resistors.

There are maybe a few thousand other ways to do it. The one above is pretty much guaranteed to be right in one individual case and utterly wrong in a few thousand other cases.

Bob

[Phoenix]

There are maybe a few thousand other ways to do it. The one above is pretty much guaranteed to be right in one individual case and utterly wrong in a few thousand other cases.

High pass filter/AC couple it with a series capacitor is my though on one of many thousand ways...

[KermitDK]

Yes it was very little info - sorry for that :-)
Let me explain :
I have a Moog Slim Phatty synth module and a Arturia Beatstep Pro sequencer.
The problem is that the Moog needs a -5 to +5 V to control the pitch, an the Arturia sends 0-10 V. (1V/Octave)
(So much for standards).
I know : "Why do you not just use MIDI ?" - Answer : "At some point I will not be able to use MIDI, so I can just as well solve the problem now" :-)
Regarding voltages, I haven´t taken the Moog apart yet, to see what voltages that are available on that, but if nothing suits - I´ll just make what is necessary.

[uncle_bob]

Yes it was very little info - sorry for that :-)
Let me explain :
I have a Moog Slim Phatty synth module and a Arturia Beatstep Pro sequencer.
The problem is that the Moog needs a -5 to +5 V to control the pitch, an the Arturia sends 0-10 V. (1V/Octave)
(So much for standards).
I know : "Why do you not just use MIDI ?" - Answer : "At some point I will not be able to use MIDI, so I can just as well solve the problem now" :-)
Regarding voltages, I haven´t taken the Moog apart yet, to see what voltages that are available on that, but if nothing suits - I´ll just make what is necessary.

Hi

Ok, you have a continuous control signal out of one box and you want to put similar range signal into the other box. The quick/ dirty offset the grounds probably is not going to work. An op amp or two is probably the best answer.

One of many ways to wire it up:
 
0 to 10V signal goes to two 10K resistors in series. Other end goes to ground. Center tap goes to the + input on the opamp. Another 10K goes from the opamp output to the - input. You can either use another fixed resistor or a 20K pot to the B+ supply to get the correct offset. Given that the 0-10 on one end may not really match up with the -5 to +5 on the other ... I'd go for the pot.

Bob

[Zero999]

Here's one way. The op-amp isn't too critical, the uA741, LM358, TL072 etc. will do.

It doesn't need a -5V reference: the LM79L05 will do.

[uncle_bob]

Here's one way. The op-amp isn't too critical, the uA741, LM358, TL072 etc. will do.

It doesn't need a -5V reference: the LM79L05 will do.

Hi

A low-ish value pot or pair of resistors off the -9V supply will do a pretty good job of replacing the 5V ref as well. That assumes that the supplies are regulated.

Bob

[KermitDK]

Thanks to all :-)
That will be tested tomorrow.
I took the Moog apart, and there is a +/- 15 V and a +/- 5V rail, so it should be possible to make it work.
(I´ll use a 7809/7909 for the LM358)

Br

Claus

[Zero999]

Thanks to all :-)
That will be tested tomorrow.
I took the Moog apart, and there is a +/- 15 V and a +/- 5V rail, so it should be possible to make it work.
(I´ll use a 7809/7909 for the LM358)

That's good but why not just run the LM358 straight from +/-15V? It doesn't need a +/-9V supply. It's just the minimum voltage required to get +/-5V out from most op-amps.

[uncle_bob]

Thanks to all :-)
That will be tested tomorrow.
I took the Moog apart, and there is a +/- 15 V and a +/- 5V rail, so it should be possible to make it work.
(I´ll use a 7809/7909 for the LM358)

Br

Claus

Hi

Generate the -5V with three 1K resistors in series. That way there is no need to find crazy value parts. Any error it adds to the gain is less than the tolerance on the two 1M resistors ....

Bob

[jwm_]

Generate the -5V with three 1K resistors in series. That way there is no need to find crazy value parts. Any error it adds to the gain is less than the tolerance on the two 1M resistors ....

I don't think the +/- 15V rails are regulated but are straight off the center tapped transformer full rectified. I could be mixing up my synthesizers though, I know some have 24V unregulated rails instead...

[uncle_bob]

Generate the -5V with three 1K resistors in series. That way there is no need to find crazy value parts. Any error it adds to the gain is less than the tolerance on the two 1M resistors ....

I don't think the +/- 15V rails are regulated but are straight off the center tapped transformer full rectified. I could be mixing up my synthesizers though, I know some have 24V unregulated rails instead...

Hi

The op-amp dies at +/- 16V. If the rails are un-regulated then you need to do something. 79L12 and 78L12 are a pretty easy pair to find and they will run ok off of a "sort of +/-15V" supply.

Bob