Using a 2N7000 LED indicator, will it not load down an input? - Page 2 - Electronic Circuits Projects Diagrams Free

Pommie · 10th February 2008, 03:56 PM

So, where exactly did that 2N7000 go?

Mike.

blueroomelectronics · 10th February 2008, 04:01 PM

I pulled the 2N7000 as I was not clear how it would affect the Analog input mode when not using a relay (not shown above). You could alway put a 2N7000 where the 2N3904 is.

I put the LED directly to the I/O pin to hopefully act as a pulldown (when the I/O is an output ie RESET) as well as an indicator in relay mode.

This schematic is one behind the current, I'll update the image ASAP
http://www.blueroomelectronics.com/u...February08.htm
It's the whole schematic (and I've added an XBEE)!

blueroomelectronics · 10th February 2008, 04:13 PM

Here's a closeup with the LED back on RLY power, and the 100K pulldown.

mvs sarma · 10th February 2008, 04:23 PM

Quote:

Originally Posted by blueroomelectronics

Here's a closeup with the LED back on RLY power, and the 100K pulldown.

Thanks Bill, for considering the suggestion. Perhaps the 100K may not be needed as you are using a bipolar, I feel. You have not used on other pins anyway.

Nice protection of relay contact. A single transient suppressor from the common connection to the return wire of the circuit on the relay contact would do. and you can save a device while still protecting the contact.

blueroomelectronics · 10th February 2008, 04:28 PM

Many of the resistors prefrom double duty. Rb1 is also used in the analog mode and as a pulldown in direct I/O mode.

mvs sarma · 10th February 2008, 04:36 PM

Sir, you may try to increase Rk1 to a higher value if the opto is workable.

blueroomelectronics · 10th February 2008, 05:32 PM

Quote:

Originally Posted by mvs sarma

Sir, you may try to increase Rk1 to a higher value if the opto is workable.

The nice part about a kit is you can change resistors values depending on your needs. Optos have a CTR ratio that will determine the current limiting resistor value.

10th February 2008, 04:01 PM	(permalink)
blueroomelectronics Experienced Member Blog Entries: 4	I pulled the 2N7000 as I was not clear how it would affect the Analog input mode when not using a relay (not shown above). You could alway put a 2N7000 where the 2N3904 is. I put the LED directly to the I/O pin to hopefully act as a pulldown (when the I/O is an output ie RESET) as well as an indicator in relay mode. This schematic is one behind the current, I'll update the image ASAP http://www.blueroomelectronics.com/u...February08.htm It's the whole schematic (and I've added an XBEE)! __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

10th February 2008, 04:13 PM	(permalink)
blueroomelectronics Experienced Member Blog Entries: 4	Here's a closeup with the LED back on RLY power, and the 100K pulldown. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

10th February 2008, 04:28 PM	(permalink)
blueroomelectronics Experienced Member Blog Entries: 4	Many of the resistors prefrom double duty. Rb1 is also used in the analog mode and as a pulldown in direct I/O mode. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

10th February 2008, 04:36 PM	(permalink)
mvs sarma Experienced Member	Sir, you may try to increase Rk1 to a higher value if the opto is workable. __________________ Regards, Sarma.

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10th February 2008, 03:56 PM	(permalink)
Pommie Experienced Member	So, where exactly did that 2N7000 go? Mike.

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