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Subject: long range IR Xmitter

Date: 07/18/01 at 8:33 AM
Posted by: Jeff Tieman
E-mail: tiemanjw@nswccd.navy.mil
Message Posted:

I in the process of designing a long range IR Xmitter for a remote control... The only part I'm haveing trouble with is the long range part. The trouble seems to be that the IR LED used only drops a fraction of the voltage (and pulls a fraction of the current) in its specs.
The current design has a FET with the cathode of the diode @ the source. Power is applied to to the anode of the diode through a resistor, and ground is @ the drain of the FET. The control signal is applied to the gate. I have tried several different resistor values (including 0), but the FET appears to impede the current draw. The FETs in the lab are old and no longer supported.

Specifically, is their a certain FET to use, or should I just try something else (a relay perhaps)?

thank you for a response in advance.

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