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psii 24th January 2006 12:26 AM

CV inverter
 
I have an ENVELOPE OUT CV signal coming from a Moogerfooger MF-101 Low Pass Filter that I want to invert. The signal, I believe, is unipolar from 0 to 5V. I am looking for a device that will accomplish the following:

IN : OUT
0V : 5V
1V : 4V
2V : 3V
3V : 2V
4V : 1V
5V : 0V

Notice I need the output to be positive voltage, so after inverting the signal I need to offset by +5V.

By googling I found this schematic:
http://web.njit.edu/~ams23/temp/cvi.gif

However, as a newb in electrical engineering, I am having trouble understanding everything going on here. I take the "K" values as resistors and the triangle in the middle as a TL074 op-amp. I'm also guessing the "[X]" input and output are some sort of 1/4" jacks. Now, what I definitely don't get is the "-15V" ... is this a battery?

So, am I on the right track or is this completely unworkable?

Any help you guys can provide would be greatly appreciated.

(The reason I am doing this is to achieve a "down" ramp instead of an "up" ramp on the MF-101. So instead of the "wow" sound you'd get an "owuh" sound.)

lineup 24th January 2006 01:52 AM

"k" is short for 'kilo' which means 1000 (like 1 kilometer is 1000 meter)

1k = resistor 1000 Ohm
TL074, is a quad Op-amp IC. With 4 Op-amps in one case.
TL072, is dual version
and
TL071 is only one Op-amp, if you only need one.

Most Op-amps needs both postive and negative supply to work.
In that figure the power supply is +15V, -15V and GROUND (0V) in the middle.
The wires from +15 and -15 that goes to Op-amp suppply pins, are not shown in picture.


You have found the right circuit to do what you want.
It can be adjusted
to give +5V, for 0 Volt input
and give 0V, for +5V input

psii 26th January 2006 09:21 AM

Quote:

Originally posted by lineup
"k" is short for 'kilo' which means 1000 (like 1 kilometer is 1000 meter)

1k = resistor 1000 Ohm
TL074, is a quad Op-amp IC. With 4 Op-amps in one case.
TL072, is dual version
and
TL071 is only one Op-amp, if you only need one.

Most Op-amps needs both postive and negative supply to work.
In that figure the power supply is +15V, -15V and GROUND (0V) in the middle.
The wires from +15 and -15 that goes to Op-amp suppply pins, are not shown in picture.


You have found the right circuit to do what you want.
It can be adjusted
to give +5V, for 0 Volt input
and give 0V, for +5V input


Thanks! Any tips for how to construct it / specific components to buy? Also, any help on how to work with 1/4" audio jacks?


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