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Driving an LED

C

Confused Soul

Jan 1, 1970
0
Hello Everyone,

I am a novice in Electronic Design. I need to drive an LED depending on
the signal I am getting out of a modem. The modem gives the output as
two different frequence (ie FSK modulated). I wanted to know different
ways to do this. As of now, I could come up with the following ideas.

1)
Vcc
|
|
|
/
\ Rc
/
|------------
Rb C
o/p of modem -----/\/\/\/----B (NPN) LED
E
|
|------------
|
|
GND

2)
Vcc
|
|
|
/
\ Rc
/
---
LED
---
|
|
Rb C
o/p of modem -----/\/\/\/----B (NPN)
E
|
|
|
|
GND

3) Another way, I was thinking of using an opamp, in which case i can
operate the LED in linear region and vary the amplitude. But the
frequency seems to be a limit.

In case 1 and 2, the LED is operated in Saturation and cutoff (like a
switch).

Is there any better ways of doing this? Please suggest me ... any
materials/links related to this wud be helpful.

Regards,
ConfusedSoul
 
M

Michael A. Covington

Jan 1, 1970
0
What is the LED supposed to indicate?
 
R

Rich Webb

Jan 1, 1970
0
Hello Everyone,

I am a novice in Electronic Design. I need to drive an LED depending on
the signal I am getting out of a modem. The modem gives the output as
two different frequence (ie FSK modulated). I wanted to know different
ways to do this. As of now, I could come up with the following ideas.

Here's a handy tool for creating ASCII circuit diagrams. MUCH easier
than fighting to do it in a text editor:

http://www.tech-chat.de/AAcircuit.html
 
S

Spajky

Jan 1, 1970
0
I am a novice in Electronic Design. I need to drive an LED depending on
the signal I am getting out of a modem. The modem gives the output as
two different frequence (ie FSK modulated).

you need a very narrow band audio filter IMHO 2-band for 1,1Khz &
2,1kHz to separate 0 & 1 signal (not sure about frequencies) first;
than IMHO aplify it to drive LEDs ... you can not do it directly IMHO
 
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