Detecting 30V Circuit is active

PDSAZ

Hi all and thanks in advance for any help.

I have an external circuit that is running at 30V DC maximum 10mA running between 2 machines.· (see attached)· on both ends are optocouplers (I believe).·(Drawing attached)·
I need to know when the circuit is active.· My hope was I could put another opto isolator inline and then use the basic stamp to detect this and turn on an LED.· Is it as simple as putting in a 4N35 with a resistor to get to the appropriate voltage?· Then I could use the transitor side to interface with my BS2 stamp is what I was thinking.

I am in the process of self teaching myself and have found·a ton of useful information on this site and I really apprecaite any assistance.

sam_sam_sam

· PDSAZ

I need to know when the circuit is active.· My hope was I could put another opto isolator inline and then use the basic stamp to detect this and turn on an LED.· Is it as simple as putting in a 4N35 with a resistor to get to the appropriate voltage?· Then I could use the transistor side to interface with my BS2 stamp is what I was thinking.

I do not see any reason why this will not work

This should help you get started

http://www.parallax.com/Portals/0/Downloads/docs/books/edu/Wamv2_2.pdf


Chapter #3: Digital Input - Pushbuttons · Page 71

[size=+0][size=+0]I know that it say the use of a switch but in your case just leave out the switch everything will be the same[/size][/size]

What do you want the Basic Stamp to do

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Sam

Post Edited (sam_sam_sam) : 8/6/2008 11:58:17 AM GMT

PDSAZ

Hi Sam,

Thanks for the quick reply.··I have attached what I believe is the correct way to do what I was thinking.

Am I correct in the following?

4N35 - Vf = 1.2v @ 10mA

Vin = 30V

30V-1.2V=28.8V· 28.8/.010= 2880 so R1 = 2880 ohm?

Basically what I need the stamp to do right now is detect when the 30V is active between the 2 machines then light an LED.· This is just to monitor for now.· The next step will be for the stamp to activate another tool based on the timing of the acitivity but I need to gather some data first.

sam_sam_sam

·PDSAZ

Am I correct in the following?

4N35 - Vf = 1.2v @ 10mA

Vin = 30V

30V-1.2V=28.8V· 28.8/.010= 2880 so R1 = 2880 ohm?

What you have here is right but i would not go so close to the max limt on any
optic sensor if it is going to be·ON all of the time I would go with something like

3100 ohms instead I try keep it below the Max 10·Millamps you could go as low as 5 millamps

·Here is a· Ohms Law Calculator that I use when trying to do·something like that

http://ourworld.compuserve.com/homepages/Bill_Bowden/ohmslaw.htm

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··Thanks for any··that you may have and all of your time finding them

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Sam

Post Edited (sam_sam_sam) : 8/8/2008 2:22:49 AM GMT

SRLM

Have a look at this link. It uses the RC time function.

http://www.emesystems.com/BS2rct.htm#B_voltage