Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Low Pass Filter design

Status
Not open for further replies.

HWguru

Junior Member level 2
Joined
Jan 20, 2015
Messages
24
Helped
1
Reputation
2
Reaction score
1
Trophy points
3
Activity points
186
Hi All,

I am trying to design and build a Low Pass Filter ( Active Filter with opamps ) . This will be the front end pre-amplifier as well as filter connected to a coil that will pick up 22hz to 32hz pulses from a Magnetic coil placed 10 feet away . I have used Filter Wiz Lite and Filter LAB2.0 , but both tools suggest using opamp of either TI or Microchip . What i need is a tool or tutorial that help design one using opamp 741 . Any suggestions ???

Thanks

HWguru
 

KlausST

Super Moderator
Staff member
Joined
Apr 17, 2014
Messages
19,487
Helped
4,308
Reputation
8,621
Reaction score
4,262
Trophy points
1,393
Activity points
129,206
Hi,

Just use 741. The values of R anc C don't change.

What opamp to use depend on other parameters like noise, input curren, offset voltage, gain....

From your description, i think you should try the 741.
For sure there are opamps with better performance.

Klaus
 

Joined
Jun 2, 2010
Messages
18
Helped
4
Reputation
8
Reaction score
4
Trophy points
1,283
Location
Bangalore
Activity points
0
Use the IC741 or try to find the opamps from the manufacturer whomever you want with the same spec of opamp which has been used in your tool.
 

HWguru

Junior Member level 2
Joined
Jan 20, 2015
Messages
24
Helped
1
Reputation
2
Reaction score
1
Trophy points
3
Activity points
186
Basically i need to amplify signal picked up from a Rx coil . The pick up coil has the impedance of 2.4Kohm and its a AWG #44 wire wound air core coil . Actually i do need a pre-amp IC with AGC so that if the TX coil is near or far the gain is controlled . What other opamp or circuit would you suggest , i need a gain x5 or x10 or ideally adjustable
 

KlausST

Super Moderator
Staff member
Joined
Apr 17, 2014
Messages
19,487
Helped
4,308
Reputation
8,621
Reaction score
4,262
Trophy points
1,393
Activity points
129,206
Hi,

2k4 source impedance .. is in a range wher a bjt or a fet opamp can be used. I'd prefer a low noise bipolar opamp.

Variable gain. You could look for automatic gain control, often made with OTAs, (compressor)
Or you could manually adjust it wit pot. Or control it with microcontroller, e-pot, multiplying DAC, or special opamp with built in gain control.

Klaus
 
  • Like
Reactions: HWguru

    HWguru

    Points: 2
    Helpful Answer Positive Rating

HWguru

Junior Member level 2
Joined
Jan 20, 2015
Messages
24
Helped
1
Reputation
2
Reaction score
1
Trophy points
3
Activity points
186
Yes i think a p-channel MOSFET should do the job
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top