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Danny
08-09-2005, 06:00 AM
I have new project coming up where I need to build a device that reads a contact closure and provides an on or off output. I was planning on using a BS2 to read the status of the signals and light indicator LEDs.
I was just asked if I could expand the sensing to include voltages as well. I was asked if it was possible to read from 5-24 VDC and then from 120-240 VAC.
I don't need to provide voltage levels, just indicate whether there is a voltage present.
I figured on using a simple resister/diode circuit to protect the BS2 from the DC voltages and provide a simple input signal to the BS2.
When the additional AC sensing was added I figured I would need to get into optical isolation.
My question is, in order to keep the device as simple as possible, I would like to use only one set of test leads for connection to the devices under test. Which means I am looking for an optoisolator that can handle ac as well as dc and up to 240 vac.
Anyone have any experience with such a beast??? Or any suggestions?

TIA!
Danny

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"Never create anything you can't control"
"The amount of intelligence on the planet is fixed... the population is growing"

Chris Savage
08-09-2005, 06:07 AM
Danny,

·· No Opto I know of can handle those voltages without a resistor.· However, Opto22 makes modules which are essentially optically isolated input modules just for this purpose.· The DC units can usually handle about 60VDC and the AC units do 120VAC no problem.· It will cost you a little more than a couple of Optos though.

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Chris Savage
Parallax Tech Support
csavage@parallax.com (mailto:csavage@parallax.com)

SPENCE
08-09-2005, 06:31 AM
DANNY. NOT SHOUTING. EASIER TO READ AND TYPE ALL CAPS.

http://www.opto22.com/products/productdrilldown/display.aspx?PartNumber=IDC5D
http://www.opto22.com/products/product_selector.aspx
http://www.parallax.com/detail.asp?product_id=27341

DOWNLOAD THE INDUSTRIAL TEXT TO GET FAMILIAR WITH SUBJECT

http://www.parallax.com/detail.asp?product_id=27341

SEE DOWNLOAD NEAR BOTTOM OF PAGE

PARALLAX ONY HANDLES A SMALL SELECTION. OPTO 22 HAS LOW VOLTAGE DC MEETING YOUR QUOTE
BUT FOR THE AC 120-240 YOU WILL HAVE TO USE ONE MODEL FOR 110 AND ANOTHER FOR 220 AC.

YES USE OPTO ISOLATION ALWAYS

73
SPENCE
K4KEP

Jonathan
08-09-2005, 06:52 AM
OK, just to show what a redneck/cheapskate I am, I have done the same thing using a neon bulb and a photodiode. A NE-2 bulb is about fifty cents and a photodiode a buck. Of course, I scrounged mine from old junk, of which a have a large supply :-0 . I simply wrapped them together with tape.

It has worked for years now though, it is part of the power supply backup for my atomic Nixie clock. When the power goes out, as it does with great regualrity where I live, it sends the WWVB reciver into low power mode, and only tries to contact WWVB once an hour and during night time only. This way I can get days of use from a 9V rechargeable back up battery.

Yehaaa,

Jonathan

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www.madlabs.info (http://www.madlabs.info) - Home of the Hydrogen Fuel Cell Robot

Jonathan
08-09-2005, 06:56 AM
Another thought...

I just re-read your post and saw that you mentioned "contact closure". If you are using a relay that is energized during runtime, a Hall effect sensor is a better solution, and a little less redneck-tech. Just glue the sensor close to the actuating coil of the realy and you are off to the races. However, if it is not energized during runtime, this won't work for you.

Yeeha,

Jonathan

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www.madlabs.info (http://www.madlabs.info) - Home of the Hydrogen Fuel Cell Robot

Danny
08-09-2005, 07:12 AM
Actually, I'm trying to build a testor for some lighting designers, they know how to paint with light, but don't know how electricity makes the things glow. Trying to build them a testor so they can see before they call me whether something (a relay or dimmer) is on and possibly providing voltage or contact closure for motorized draperies.
These people will tell me my programming is wrong when a bulb is burned out. Seems they think micros can reprogram themselves on the fly.
Before I have to walk them through using a meter, I want give them something with aligator clips or even a light bulb base with leads that they can plug into a socket and see if there is juice when they push the button. The aligator clips would be for connection to terminal strips, God forbid they try to put aligator clips in a socket, we'd have fried lighting designer.
I have plans to make it do more, that's why I'm basing it on a stamp.
Hope that makes the questions clearer.
TIA!

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"Never create anything you can't control"
"The amount of intelligence on the planet is fixed... the population is growing"

Beau Schwabe
08-09-2005, 10:21 AM
Danny,

A few years (10+) ago I designed an automatic vacuum system for multiple grinding workstations... I was only dealing with
120VAC on the sense end. I basically tied a 1M resistor inside of each station with a single "leader" wire leaving each one to
detect when a machine was turned on. Here is a schematic of the front end of the vacuum system that I used. Just a few
years ago, when I made a trip back to see some of my old work friends, this was still in operation.


As with any project dealing with the mains, be EXTREMELY careful, electricity can kill.

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Beau Schwabe (mailto:bschwabe@parallax.com)

IC Layout Engineer
Parallax, Inc.

Post Edited (Beau Schwabe (Parallax)) : 8/9/2005 2:37:45 AM GMT

stamptrol
08-09-2005, 11:16 PM
Danny,

If you use a H11AA1 opto coupler, the input side can be either AC or DC. The output is a phototransistor which can be connected to the Stamp pin with the usual pull-up resistor.

Then, your only problem will be choosing the input limiting resistor. It has to be high enough to limit current at the absolute maximum voltage but low enough for the lowest voltage to give you a readable input at the Stamp.

Or, you could have a switch selectable resistor for each range.

Cheers,

Tom Sisk

Azitek
04-19-2006, 12:06 PM
Hello,

My question is somewhat - but not directly related to this thread. I have read a number of posts and attempted to research related product information, however, I could not find exactly what I am looking for.

Just like the original thread, I·will also be controlling higher voltage motors (in my case 48V, 200mA) using a Basic Stamp chip. I would like to opto isolate the motor's power from the chip. I will be using 6 motors, probably via a relay. Here is my question:

Do I need to use a separate "opto coupler" for each I/O of my Basic Stamp or are there opto couplers that will be able to accomodate multiple I/O configurations.

Please excuse my ignorance, but I am as new to the world of microcontrollers as can be.

Thanks for any help.