optcoupler help

Archiver

Hello,
Still working on the chore/catbox project. I'm using 25 feet of 2 conductor
speaker wire. I'm using GE h11a1 8524 optocopler. I don't have a pin out, but
I'm assuming it is like RS's triac version. + to pin 1, - to pin 2 (both from
origional circuit), and + supply to pin 4, and signal out on pin 6. The trouble
is I'm always regestering a logic 1 on my stamp. Should I put a pull down
resistor on the signal line near the stamp? Want to register 3 states of the
signal line on the stamp. on/off and flashing.

Currently using count, if count if greater then X, goto flash routine. If not
check for on or off.
Linux user #228897 computer #109948
website http://www.capdiamont.com


[noparse][[/noparse]Non-text portions of this message have been removed]

Archiver

The output of the H11A1 can be used like an NPN BJT. You will probably not
need to use the base connection on pin 6, unless you want to have a
non-isolated input. Pins 1 & 2, as you state are anode and cathode of the
input emitter (LED)respectively, and current needs to be limited by a
resistor and a quick calculation using Ohm's Law. When doing so, begin by
using the maximum forward voltage drop shown on the data sheet for the
emitter section of the chip, which I think is somewhere around 1.5 V. Note
that the life expectancy of the device is inversely proportional to the
current through it. If your ap is not CTR or time sensitive, you may try
only a handful of mA for longest life. Just be sure you have enough current
in the loop to ensure reliable operation. Since the detector section could
be described as a photo-sensitive NPN BJT, you would want to bias it
properly. If you are only using the isolated base input, you need to be
primarily concerned with the load resistor that's between the collector (pin
5) and Vcc. The point between the load resistor and the collector is your
output. Again, select a load resistor that will give you current that the
device can handle safely, and remember that your output will now be
inverted.
If you need to use the base connection at pin 6, you'll need to be up on
your biasing technique and will need to use the curves provided in the
datasheet for that purpose.

If you haven't already found the full data sheet, go to
www.fairchildsemi.com where I believe you'll also find ap notes.
Chris

>

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Original Message

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> From: capdiamont [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=HmZPXj6u2RrDbBSrRixyqIIgi6qlo7C-W_qa2JVSenKXSHgbVgbsKjINCkWOIbCLmpY8p9x68ovfgv9h]capdiamont@m...[/url
> Sent: Monday, October 08, 2001 10:29 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] optcoupler help
>
>
> Hello,
> Still working on the chore/catbox project. I'm using 25
> feet of 2 conductor speaker wire. I'm using GE h11a1 8524
> optocopler. I don't have a pin out, but I'm assuming it is
> like RS's triac version. + to pin 1, - to pin 2 (both from
> origional circuit), and + supply to pin 4, and signal out on
> pin 6. The trouble is I'm always regestering a logic 1 on my
> stamp. Should I put a pull down resistor on the signal line
> near the stamp? Want to register 3 states of the signal line
> on the stamp. on/off and flashing.
>
> Currently using count, if count if greater then X, goto flash
> routine. If not check for on or off.
> Linux user #228897 computer #109948
> website http://www.capdiamont.com
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>
>
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