PWM Generator for network avaialble indicator (heart beat)

[_Thinkpad_]

Hi,
I am looking for a PWM generator to switch a Network indicator LED on once a second and stay on for a few ms. The LED wiil be powered by the output from the network status pin of a transceiver.
Hence when the network is available the LED will blink once every 1 sec to indicate a healthy network. when the network is off the LED is OFF.

Thnks,
TP

 

[SeungminLee]

Why don't you employ a micro-controller?
It's cheap and work effectively. I think you can do your stuff easily with MCU.

 

[karesz]

Hi,
I think its a simple job for 555 with double, or switched, time constant/pulse width too...
K.

 

[_Thinkpad_]

Re: PWM Generator for network avaialble indicator (heart bea

Thanks for the replies. i was lookin for a quick fix, like an iC that i cud just use as a switch. This unit goes in a production unit, so uc option will require additional overhead on the assembly line.

 

[karesz]

your welcome!
If your goal is a pulsed modus(burst of some msec pulses) over i.e. a half sec if the network is on:
Build pls a 150-300Hz pulsegenerator with an 555, and with anoder (generates i.e. 1Hz) 555 gate it!
So will your eye a continuous light see for a half second, but the LED`s energy consume is not so high as if has a DC exitation...
Or it can be a 556_a 2x 555_ in an SMD 16 pin IC_ but Im really not a fun of 555!
The second half of 556 (the 0.5 sec gating part/1 sec astable) will you trigger with your "LED-Start/flash" signal.
I think; thes is similar as you can like
K.

 

[_Thinkpad_]

Thanks for the reply. What i had in mind was to power the PWM generator by t he transceiver output. The LED will thus be ON for say 100ms every second

 

[karesz]

OK,
Then what you need is only a trigered/inhibited astabil multivibrator (with 10% duty cycle, but eventually you will have/need some more); an 555
(or simplest a 2 transistors multivibrator), wher you can gate/stop_or start_ with an external signal...
Here are some better apps to find: **broken link removed**
K.