Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic 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.

Register Log in

open loop & closed loop

Status
Not open for further replies.

gfigo

Newbie level 3
Joined
Dec 26, 2005
Messages
3
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,307
Hello,all!Who can tell me what are open loop and closed loop?and the difference between them,Thanks in advanced!
 

flatulent

Advanced Member level 5
Joined
Jul 19, 2002
Messages
4,629
Helped
489
Reputation
980
Reaction score
150
Trophy points
1,343
Location
Middle Earth
Activity points
46,689
This involves feedback systems. Open loop is the gain and phase around the loop when the feedback is disconnected. Closed loop is the output/input transfer function with the feedback connected.

An example for an amplifier in closed loop is that the gain is more constant as a function of frequency.
 

    gfigo

    points: 2
    Helpful Answer Positive Rating

paulux

Advanced Member level 4
Joined
May 16, 2005
Messages
112
Helped
11
Reputation
22
Reaction score
2
Trophy points
1,298
Activity points
2,339
The loop concept comes from control system. An open-loop control system utilizes actuating device to control the process directly without using feedback.
A closed-loop control system uses a measurement of the output and feedback of this signal to compare it with the desired input.
 

    gfigo

    points: 2
    Helpful Answer Positive Rating

gfigo

Newbie level 3
Joined
Dec 26, 2005
Messages
3
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,307
Your answers are very helpful for me , thanx! but there's a new question:How can I distinguish negative feedback from positive feedback?
 

eda_freak

Member level 3
Joined
Jun 20, 2005
Messages
62
Helped
12
Reputation
24
Reaction score
2
Trophy points
1,288
Activity points
1,997
Hi gfigo,

feedback can be of two types. positive and negative..
in positive feedback the resultant output causes the input to be added in constructive manner. you can say positive feedback systems are self sustaining..
example is a simple oscillator which is critically fedback. in negative feedback systems the output adds to input in destructive manner. these systems tend to get into a steady-state easily example is any damped system.
 

    gfigo

    points: 2
    Helpful Answer Positive Rating

electronics_kumar

Advanced Member level 2
Joined
Nov 29, 2004
Messages
659
Helped
34
Reputation
68
Reaction score
9
Trophy points
1,298
Location
Tamilnadu
Activity points
5,552
adding tincture to wounds ie curing mechanism comes under feedback system...
Indeed prevention is better than cure but for preventing of any untoward incident is not at all possible...so we are going for curing mechanism...
If we are having very good curing mechanism(feedback),the we can include /increase dynamism in our system...

Added after 3 minutes:

i heard that closed loop concept starts from the world war....
 

    gfigo

    points: 2
    Helpful Answer Positive Rating

gfigo

Newbie level 3
Joined
Dec 26, 2005
Messages
3
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,307
Thank you,guys! Your answers are very clear and interesting. but can you tell me whicn world war it is?haha.
 

sabu

Junior Member level 3
Joined
Sep 20, 2005
Messages
31
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,286
Activity points
1,517
in feed back systems the system can know wt is happening at the o/p.so it can control it actual i/p, there by the o/p can track the input in a controlledmanner.
regards sabu
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top