Help with Ground - Page 2 - Electronic Circuits Projects Diagrams Free

CuentaChocula · 28th February 2007, 02:11 AM

Quote:

Originally Posted by audioguru

The opamp looks like an old uA709. Remember them? It is even older than the old uA741 opamp.

Opamps don't need bipolar power supplies if their inputs are biased correctly near the center of a single supply voltage.

It is a uA709. The design calls for a "Fairchild uA709C" and also cautions against getting a "dual, in-line, or flatpack" package and says "be sure you get it in the TO-5 package." I must not have read this at the time because I got the DIP one. Maybe it's all that was available in 1989 or so when I bought it at Hatry Electronics in New Haven, CT.

audioguru · 28th February 2007, 02:20 AM

I remember seeing old opamps in a TO-5 metal case.

Hero999 · 28th February 2007, 10:00 PM

http://www.uoguelph.ca/~antoon/gadgets/741/741.html

audioguru · 28th February 2007, 10:35 PM

He, hee. Bob Widlar who designed those old opamps retired before he turned 30 years old! That was 42 years ago.

JTECH · 28th February 2007, 11:39 PM

If the signal processed by the op-amp is ac, then you don't need a dual supply, provided the op-amp is biased properly and use is made of input and output coupling capacitors.

Sceadwian · 1st March 2007, 01:47 AM

What you're talking about is a split supply opamp, not a bipolar opamp. BIG difference. Bipolar opamp means it's made from bipolar transistors not FET's. Like CMOS opamps are.

audioguru · 1st March 2007, 02:07 AM

Bi-polarity power supply?

Gaston · 2nd March 2007, 12:55 AM

Quote:

The opamp looks like an old uA709. Remember them? It is even older than the old uA741 opamp.

was that made with vacuum tubes? : ) just kidding

**Nigel Goodwin** · 2nd March 2007, 07:38 AM

Quote:

Originally Posted by Gaston

was that made with vacuum tubes? : ) just kidding

The first opamps were!.

Hero999 · 2nd March 2007, 10:43 PM

From the link above:

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28th February 2007, 02:20 AM	(permalink)
audioguru	I remember seeing old opamps in a TO-5 metal case. __________________ Uncle $crooge

28th February 2007, 10:00 PM	(permalink)
Hero999	http://www.uoguelph.ca/~antoon/gadgets/741/741.html __________________ I also post at the following sites: http://www.stop-microsoft.org http://www.heated-debates.com Screen name: Aloone_Jonez And http://www.silicontronics.com, same screen name as here.

28th February 2007, 10:35 PM	(permalink)
audioguru	He, hee. Bob Widlar who designed those old opamps retired before he turned 30 years old! That was 42 years ago. __________________ Uncle $crooge

28th February 2007, 11:39 PM	(permalink)
JTECH	If the signal processed by the op-amp is ac, then you don't need a dual supply, provided the op-amp is biased properly and use is made of input and output coupling capacitors.

1st March 2007, 01:47 AM	(permalink)
Sceadwian	What you're talking about is a split supply opamp, not a bipolar opamp. BIG difference. Bipolar opamp means it's made from bipolar transistors not FET's. Like CMOS opamps are. __________________ "Because I be what I be. I would tell you what you want to know if I could, mum, but I be a cat, and no cat anywhere ever gave anyone a straight answer, har har."

1st March 2007, 02:07 AM	(permalink)
audioguru	Bi-polarity power supply? __________________ Uncle $crooge

2nd March 2007, 10:43 PM	(permalink)
Hero999	From the link above: __________________ I also post at the following sites: http://www.stop-microsoft.org http://www.heated-debates.com Screen name: Aloone_Jonez And http://www.silicontronics.com, same screen name as here.