#### Re: RX and TX LED

MVS Sarma

just for indication.
at 12V you better use 4K7

regards
sarma
vu3zmv

regards
Sarma

On Mon, Nov 6, 2017 at 1:42 PM, Michael Hagen wrote:

Using 680 ohms will really make the LED bright.  I = (12V - 3.3V ) / 680.  Most work real nice on just a few ma.  2.2K should give nearly 5 ma.  What folks are saying is an LED is not "operated" or "biased" with voltage.  You put a current thru them, and the voltage is just a result.  You get what you get!

The current limit resistor is picked for how bight you desire it to be.   The 3.3V spec will be the approximate voltage drop at a given current.

If you were running on a battery, you might try only 1 or 2 ma.

Just a thought, most take 20 ma. OK.  For an experiment, try 10K and then 1K?

Mike, WA6ISP

On 11/5/2017 9:52 PM, Prathap Naidu wrote:

You can use a dual color LED with 3 leads, centre is common gnd.

I have used a standard 3mm LED , you can also use 5 mm if you need, but the 3 mm is quite Ok

The 680 ohms is the dropping and current limit resistor, I have tapped the 2 wires from the K1 relay which alternates the +12V between Rx and Tx

73 Pop

VU2POP

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Ben Piecora
Sent: Monday, November 06, 2017 11:11 AM
To: BITX20@groups.io
Subject: Re: [BITX20] RX and TX LED

Thank you VU2POP. Is the yellow wire for RX and the green wire for TX and then the 680 ohm resistor goes to ground? Is the LED 12 volts? I was planning on using a Red 3.3 volt LED to indicate TX and a green 3.3 volt LED to indicate RX

73

Ben

Kd2nou

On Mon, Nov 6, 2017 at 12:37 AM Prathap Naidu <vu2pop@...> wrote:

Hi ben

See attached pics, solder 2 wires below the K1 relay as shown, then to the Dual color LED , the centre of the LED goes to ground thru a 680 Ohms restistor.

Have fun

happy Bitxing

73 Pop

VU2POP

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Ben Piecora
Sent: Monday, November 06, 2017 2:51 AM
To: BITX20@groups.io
Subject: [BITX20] RX and TX LED

Hi Everyone,

Could anybody tell me a way I can pull voltage from the board for an LED on RX and then pull voltage from the board for a TX LED and turn off the RX LED?

Thanks

Ben

KD2NOU

--

Ben

KD2NOU

--

Ben

KD2NOU

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