[ppl]

Virtual ground drivers while a must for battery operated opamp Equipment are also good for AC supplys Like you have a wall wart with only Vcc and Gnd. also a Virtual ground Driver will remove Noise present on the Center tap of a transformer> this is one reason dual Bridge rect's are used on the finest Equipment using split rail supplys and at least one manufacture uses a separate Transformer for each rail. When i do AC supplys I use a tranceformers without a center tap but rather Two separate secondaries then make a true Full wave Bridge for each Secondary to Create Tow galvanicly isolated Power supplys then conect the two in series. I have found Virtual Ground drivers to be Verry easy ti impliment and do not get hot unless you are sinking or sourcing close to the drivers rated current in this case. Just like the output stage would. In the late 80's Acoustat transnova used the Virtual ground Driver to supply the Audio and the Amps output stage to just sink and source Current.

<<<<DISCLAIMER>>> the above is only My Method of Obtain ing a good AC supply other equaly valid methods are availkable depending upon the requirements.

 

[Tomo]

Hello,

I agree. I use seperate secondaries also. (Or I prefer to do so.) I have seen several different ways to connect two secondaries on an article a while ago.

Though I believe the effect might be relatively small if the virtual ground is well-grounded and bypassed well with good enough capacitances. (Note when you do this, many prefers to separate signal ground from power supply ground.)

Tomo

P.S.

ppl- Thanks for the pics. I will look at it this weekend.

 

[ppl]

Tomo: Glad you got the Pictures ok. Regarding isolating the Grounds I isolate the Input from all others Via about a 10 ohm resistor sometimes cap bypassed. then isilate the Gig between the Power supply caps so as to keep the large curent spikes from causing Hum oe worse then a comon Ground Perferably on a ground Plane that has the output Load return and all Powersupply capacitors. This technoque workse very well for me. If yoy do not have schematics for my Headphone amps search these fourms To find the Site hanson was so kind to post them on