Question about the NE5532 op amp split supply virtual earth

[6666]

Hi George
I was wondering if you would mind replying with your technical expertise on a very general question about the NE5532 op amp split supply virtual earth.



I have been looking at testing some experiments on for example the PI2 which has the NE5532 split supply .

If I was to replace the fet switch with a CD4066,
and Useing a 10 volt battery I was going to try +- 5volts on the 4066 supply and switch the 4066 with virtual ground and -5 volts, do you think the split supply regulation could handle the 4066, or would the load upset and unbalance the regulation too much ? Thanks.

[Qiaozhi]

Hi George
I was wondering if you would mind replying with your technical expertise on a very general question about the NE5532 op amp split supply virtual earth.



I have been looking at testing some experiments on for example the PI2 which has the NE5532 split supply .

If I was to replace the fet switch with a CD4066,
and Useing a 10 volt battery I was going to try +- 5volts on the 4066 supply and switch the 4066 with virtual ground and -5 volts, do you think the split supply regulation could handle the 4066, or would the load upset and unbalance the regulation too much ? Thanks.

Off the top of my head, I would think the NE5532 would be more than capable of supplying the current requirements of the CD4066.
I know of designs where a split supply is used to power the whole analog section.

[6666]

Thanks much appreciated, I will give it a try.

[green]

Hi George
I was wondering if you would mind replying with your technical expertise on a very general question about the NE5532 op amp split supply virtual earth.



I have been looking at testing some experiments on for example the PI2 which has the NE5532 split supply .

If I was to replace the fet switch with a CD4066,
and Useing a 10 volt battery I was going to try +- 5volts on the 4066 supply and switch the 4066 with virtual ground and -5 volts, do you think the split supply regulation could handle the 4066, or would the load upset and unbalance the regulation too much ? Thanks.

Maybe I'm thinking wrong. 4066 with 10V supply requires at least 7V above the -rail to switch. Are you asking if you can switch with 5V?

[Skippy]

That's my concern, too. The 4066 only has one +ve supply rail, so you can't do fancy tricks with seperate digital / analogue levels. If this is what you need, there are many up-market analogue switches with logic-level inputs, and different analogue rail potentials.

[Qiaozhi]

Maybe I'm thinking wrong. 4066 with 10V supply requires at least 7V above the -rail to switch. Are you asking if you can switch with 5V?

That's my concern, too. The 4066 only has one +ve supply rail, so you can't do fancy tricks with seperate digital / analogue levels. If this is what you need, there are many up-market analogue switches with logic-level inputs, and different analogue rail potentials.

I think that 6666 is asking if he can use a +10V supply with a virtual ground to provide +/- 5V for the 4066. In which case that's the same thing as having a +5V supply and generating a -5V supply with an LT1054 (for example). Both cases will provide a ground reference with + and - 5V supplies.

[green]

I think that 6666 is asking if he can use a +10V supply with a virtual ground to provide +/- 5V for the 4066. In which case that's the same thing as having a +5V supply and generating a -5V supply with an LT1054 (for example). Both cases will provide a ground reference with + and - 5V supplies.

What does and switch the 4066 with virtual ground and -5 volts mean?

[Qiaozhi]

What does and switch the 4066 with virtual ground and -5 volts mean?

Have a look at the Hammerhead schematic as an example that uses 4066 CMOS switches. This uses a 12V battery with the +ve rail as a ground reference. A 79L05 is used to generate the -5V supply, and a 7660 is used as a voltage doubler to feed a 78L05 to create the +5V supply. In this case we have + and - 5V supplies with a ground reference (+ve terminal of battery). The 4066 is powered by the +/-5V supplies, and (although the 4066 does not have a connection to the ground reference) the control and input pins need to swing between + and - 5V, so the ground reference is used by the preamp and the timing circuits.

Now ... if you were to throw away the 7660 and the voltage regulators, it would be possible to generate the +/-5V supplies from a 10V input by configuring an opamp to create a virtual ground. Effectively you then have the same result. The 4066 has its +/-5V supplies, and the preamp and timing circuits can use the virtual ground as a reference. However, how stable this configuration would be compared to the original setup is perhaps another story.

[6666]

The purpose of my simple micro based hybrid project is to bring together a great number of PI ideas that I have been wanting to experiment with for some time.
If it works the PI requires a 4066 switch powered from +5 and -5 volts, and the 4 gates are switched with gnd (positive battery) and -5 volts.
This analogue system already seems to work in the XL500 as shown in the attachment
One of the many goals with this experiment is to use simple power supplies, hence my question to George about the virtual earth split supply in his PI2 project, to supply the +- 5 volts,
as I am concerned that the 4066 may load the split supply and unbalance it, and may not work.

Part of my circuit requires jfets to be replaced with the 4066, as correct jfet biasing creates problems for me, thats why I got excited when Ivconic got his Bara working with an Arduino.
I am still recovering from the flu and my concentration level is still almost zero, but I have done a few brief tests with the 4066 and it seems to switch leds ok, but will it switch and pass a PI preamp signal is the big question, as I am not sure just how hard the 4066 switch's on.
You can see the power and switching in the attachment.

[6666]

What does and switch the 4066 with virtual ground and -5 volts mean?

Hi Green the attachment shows the 4538's switching the 4066 gates with ground (positive battery) and -5 volts
if I can get this to work with a simple split supply it would be very handy. But I may have to go back to using real regulators etc.

[6666]

Now ... if you were to throw away the 7660 and the voltage regulators,

Thanks George for writing all that, it explains the principle of my experiment.