How to run TL072s on a single supply?

j.dilisio · Joined: May 19, 2009 Posts: 200 Location: baltimore

I need to buffer the trigger outputs on my tr-606 and I've got a bunch of TL072s I'd like to use but they need a bipolar supply.
The 606 runs on 6v dc.
I came across this bit of info in another forum..

"Audio amps are not single supply. You will need to split the supply
(+/- 4.5V) or invert it (+/- 9V) to create a signal ground."

So my questions are:
What is the easiest way to invert or split a dc supply?
Is there an easier/better way to buffer the outputs?

Thanks,
J

Sound · Joined: Jun 06, 2006 Posts: 842 Audio files: 1

If you put two same value resistors in series from +6 to Ground, in its node you will create a virtual ground at 3V.

j.dilisio · Joined: May 19, 2009 Posts: 200 Location: baltimore

Oh, cool.
I'll give it a try. Very Happy

Sound · Joined: Jun 06, 2006 Posts: 842 Audio files: 1

j.dilisio also you could buffer the trigg with a logic chip. But I don't know which one its the appropriate. Does anyone know?

j.dilisio · Joined: May 19, 2009 Posts: 200 Location: baltimore

Wait a sec,. when you wire these up as buffers nothing gets hooked up to ground. So without a ground or virtual ground to reference, what's the difference between a bipolar and single supply?

Also, it doesn't say in anywhere in the datasheet what the minimum supply voltage or range is. Does anyone know if +-3v is enough?

numbertalk · Posted: Tue Apr 20, 2010 6:22 am Post subject:

Take a look at how stompboxes do it. Here's a buffer circuit that runs off of a single 9V supply with a TL071 used as a voltage follower/buffer run with ground and the +9V supply - maybe wiring up your TL072 something like this would work for you?

http://www.generalguitargadgets.com/pdf/ggg_icbuf_sc.pdf

PHOBoS · Posted: Tue Apr 20, 2010 11:18 am Post subject: creating virtual GND

Here are 2 methods I use. Usually the first one will suffice, but If I have a circuit with a couple of opamps that need GND, I go for the second one which is more stable.

opamp-voeding.gif

Description:

virtual GND from single power supply

Filesize:

4.79 KB

Viewed:

177 Time(s)

This image has been reduced to fit the page. Click on it to enlarge.

nicolas3141 · Posted: Thu Apr 22, 2010 1:49 am Post subject:

Using a spare opamp to do it the second way is good. But really needs 9V or 12V or more for most opamps. On 6V you are only getting +/-3V and TL07x opamps can't do input/output voltages that are anywhere close to the rail voltages. They like to stay at least 2 or 3 volts away from both rails. Which means on +/-3V you can really only handle signals of a few millivolts before things start to deteriorate.

There are some opamps designed for low voltage operation that can handle signals close to their rail voltages. Better to use one of them.

Cheers,
Nicolas

j.dilisio · Joined: May 19, 2009 Posts: 200 Location: baltimore

This is what I ended up doing..
Posted Image, might have been reduced in size. Click Image to view fullscreen.

There's a slight loss in signal but otherwise it works fine. I can plug the trigger outputs into each other without them affecting one another.

The opamps were giving me a constant 2v output at all times.
It also says in the datasheet that the input voltage should not exceed +V or 15v, whichever is less.