Re: modulating a ramp into a IR transmitter
- From: Joerg <notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx>
- Date: Sun, 10 Dec 2006 23:37:05 GMT
Bluespace Technologies wrote:
"J.A. Legris" <jalegris@xxxxxxxxxxxx> wrote in message news:1165758126.667410.136910@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Bluespace Technologies wrote:
Hi All,
This is a circuit design question for IR data emitters.
Currently I am using a 455 Khz signal to drive an IR LED with pulsed data
modulation at 20 KHz. I want to modulate the data using a ramp circuit
instead of a data pulse (i.e. a ramp replaces the pulse). Does anyone know
how I can modulate a ramp into the 455 khz driver signal? I already have a
ramp generator using a timer circuit, but modulating the ramp into the LED
using a single transistor provides too weak a drive signal to run the LED,
hence reducing its range of operation. How can I modulate a ramp into the
drive signal to get more output power, hence more range?
Thanks for your help!
Why do you want to use a ramp?
Have you considered PWM?
--
Joe Legris
Basically, that is the idea. I want a ramp to receive a pulse that varies
with the strength of the transmitted signal. If the transmitted signal is
strong then the received pulse width is longer, etc.
-Andrew
Sounds a bit unorthodox. Well, but so are many of my circuits. One method to modulate is "robbing LED current". IOW use a current source to drive the LED and another circuit that gradually steers that current into ground. Or vice versa, depending which direction you want the ramp.
Look at laser diode driver app notes for details.
--
Regards, Joerg
http://www.analogconsultants.com
.
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- From: Bluespace Technologies
- Re: modulating a ramp into a IR transmitter
- From: J.A. Legris
- Re: modulating a ramp into a IR transmitter
- From: Bluespace Technologies
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