Replacement part for LMV821

Thread Starter

NewStudent

Joined Feb 16, 2008
25
I need a replacement part for the LMV821 - 5MHz, Low Voltage, Low Power, RRO, 5 MHz Op Amps. The LMV821 only comes in a SC70-5 and I need a DIP.

Any suggestions?
 

SgtWookie

Joined Jul 17, 2007
22,230
Fairchild Semiconductor has a pretty good parametric search engine as well.

Mouser.com also has a decent parametric search - and it's cross-vendor.
 

Thread Starter

NewStudent

Joined Feb 16, 2008
25
Fairchild Semiconductor has a pretty good parametric search engine as well.

Mouser.com also has a decent parametric search - and it's cross-vendor.
Hi SgtWookie

No, this is not an homework assignment. I'm trying to build a souped up ultrasonic range finder.

I found this circuit at:
http://www.edn.com/index.asp?layout=article&articleid=CA45965

I thought I'd build and test it's performance, but I can't locate the LMV821 in a DIP package so I need an equivalent. I've searched the web, read a lot of data sheets, and found the TS1871 and the LM6132. Unfortunately, I don't know enough electronics to recognize what parameters are necessary for an equivalence for this application.

Secondarily, the schematic fails to identify T1 specifying only 200:8. I recognize the symbol for a transformer. Does the 200:8 represent a winding ratio? Does the 200 side connect to the transmitter? Can I buy this part or do I need to make it?

Thanks for the help

p.s. What is a parametric search?
 
Last edited:

SgtWookie

Joined Jul 17, 2007
22,230
No, this is not an homework assignment. I'm trying to build a souped up ultrasonic range finder.
OK, just checkin' ;)
They sure come up with some intriguing ideas - and some really goofy ones, too!
I thought I'd build and test it's performance, but I can't locate the LMV821 in a DIP package so I need an equivalent. I've searched the web, read a lot of data sheets, and found the TS1871 and the LM6132. Unfortunately, I don't know enough electronics to recognize what parameters are necessary for an equivalence for this application.
Why not go with an LMV821? Just design a circuit board for it, and make provisions for the pads. The dimensions are right there in the datasheet. Then solder that bug right to the board!

Secondarily, the schematic fails to identify T1 specifying only 200:8. I recognize the symbol for a transformer. Does the 200:8 represent a winding ratio? Does the 200 side connect to the transmitter? Can I buy this part or do I need to make it?
You can use an audio output transformer; 200 Ohms on one side, 8 on the other. Yes, it's a ratio of turns. Radio Shack doesn't stock a suitable transformer; the only one they carry is 1000:8. You could wind your own if you were ambitious or bored. Or you could buy one from someplace like Mouser or perhaps a salvage place or online auction for a couple of bucks.

What is a parametric search?
You supply the parameters you want to search for, and click "search"
 

Papabravo

Joined Feb 24, 2006
21,094
...
Secondarily, the schematic fails to identify T1 specifying only 200:8. I recognize the symbol for a transformer. Does the 200:8 represent a winding ratio? ...
In my mind, at least, there is some ambiguity on the 200:8. It could be either a turns ratio OR an impeadance ratio. IIRC the impedance ratio is the square of the turns ratio.

If it was a turns ratio it could have been expressed as 100:4 or 50:2 or 25:1. If it was an impedance ratio then there must be something about the values 200 and 8 that you can identify in the external circuit.

I suppose you could email the magazine or the sauthor seeking a clarification.

Good luck I hope you figure this one out.
 
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