A47

[Username 0]

I was looking at a A47 schematics on HeadWize and I realise that they didn't include the power supply schematics. Can I use the CMOY power supply design? If yes, how do I connect the power supply to two opamp.

[jasonhanjk 0]

Yes, you can use the same Cmoy circuit. I don't understand the second question...

[Username 0]

For a typical cmoy, the +ve side of the power supply goes to the +ve side of the opamp, now that we have got 2 opamp how do we connect the power supply up to the 2nd opamp, in series or in parallel?

[jasonhanjk 0]

If you are saying the opamp in the same IC, they share the same power supply. + at pin 8 and - at pin 4. If you want to connect to the 2nd IC, you need to connect it in parallel.

[Username 0]

Thanks Jason, that answered my question.

[Firefox 0]

If you can, I highly³ recommend using a buffer for the virtual ground.

[Username 0]

How long approximately will a 9-volt battery power a A47? Will it be comparable to a CMOY?

 

I am worried because of this phrase in the original A47 scrapbook on headwize:

"The resistor-divided 9V battery in the original spec it will not power it very well or for very long - maybe 2 hours. "

[jasonhanjk 0]

If you use 150mAh 9V battery, it will very well last 4 hours.

[Username 0]

Thanks for the reply, but is there anyway to improve the battery life?

[jasonhanjk 0]

Yes, wait for me to design another new amp...... hahaha....

 

New opamp utilise on newer 3.3V technology and they promise better power utilisation BUT they will never sound better than their higher voltage counterpart. The lower the voltage the worse the transistor linearlity becomes.

You can build something like Portable amp 2, that really saves a lot of juice.

[heady 0]

Thanks for the reply, but is there anyway to improve the battery life?

You can built the amp designed by Sijosae using the 74HCU04, it sounds quite good compared to the CMOY and uses two AA batteries which last a longggg time.

Edited April 18, 2005 by heady

[heady 0]

Yes, wait for me to design another new amp...... hahaha....

 

New opamp utilise on newer 3.3V technology and they promise better power utilisation BUT they will never sound better than their higher voltage counterpart. The lower the voltage the worse the transistor linearlity becomes.

You can build something like Portable amp 2, that really saves a lot of juice.

Hey Jason, I am waiting.... But do you have schematics for the PAv2?

[jasonhanjk 0]

No. Give me half an hour.

[jasonhanjk 0]

From LM4881 datasheet.

[Username 0]

Heady: Where can I get the schematics for the 74HCU04? EDIT: found IT~!

 

Jason: Is that the schematic for the PA2V2?

Edited April 18, 2005 by Username