HP461a amplifier--is it a inverting amplifier??

[alimjoco]

Hi guys,

Is anyone used hp461a amplifier..it has gain of 20db and 40db..is it an inverting amplifier..I used to amplify an AC ripple of DC converter and it seems it has an inverted signal response.

 

[alexan_e]

I don't think so according to http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1964-03.pdf

Alex

 

[ckshivaram]

check this.... i dont feel it is invertring amplifier

http://www.hparchive.com/Journals/HPJ-1964-03.pdf


sorry if it is double post... maybe a slight time difference in posting the answer...........

 

[FvM]

It's the pulse response shown in the article, that suggests non-inverting operation, also common-sense of instrument design. The block circuit, that describes 5 cascaded common emitter stages would refer to inverted operation, however.

Can't the real behaviour easily determined?

 

[alexan_e]

FvM, the article above Fig5 page 2 shown two emitter followers (not common emitters) with a five stage amplifier in the middle

Alex

Edit: you were referring to the 5 stage amplifier not the emitter followers stages I mentioned

 

[alimjoco]

i checked in the scope, the amplified sine wave vs. the input sine wave..although the gain is right , they are not in phase..its like they are 180 out of phase...why is that? need expert on amplifiers..thnks

 

[FvM]

What's your problem with inverting amplifier operation? Does your oscilloscope haven't an "invert" switch?

I previously explained why the HP461A block diagram suggests inverted operation. If you have a service manual with circuit diagram, we can explain more.

 

[alimjoco]

ok ..just want to sure that my ripple test with or without a pre amplifier have the same response(one with a gain). The out of phase as you mentioned is only caused by the pre amplifier(hp461a)