VAC detection
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Posts: 46,084
I need to detect the presence/absence of 24VAC on a line with a Stamp
PIO. Can anyone tell me how to do this cheaply? I looked for a
24VAC coil relay at the local electronics store, but couldn't find
one.
/John
PIO. Can anyone tell me how to do this cheaply? I looked for a
24VAC coil relay at the local electronics store, but couldn't find
one.
/John
Comments
There are many ways to skin a cat. Here are a few, and I'm sure you'll see
plenty of others (probably better ideas) in here shortly...
If you want inexpensive and safe for the stamp, I would divide the 24VAC
with a resistor network, do a little rectification, full wave would be nice,
and smooth it with a cap. That could be input to an opto-isolator with a
transistor output which outputs to your stamp pin safely. About $5.
You could do this without the isolation and with a small cap if you like,
but I always prefer opto's.
Equally as safe and reliable would be to use a current transformer on the
24V, but you would still need to rectify and filter the output. More costly,
but more industrial in nature.
I suppose 1/2 wave rectified and divided, you could input to a 555 and
output to the stamp also. This might also be inexpensive, but it's
definitely not the safest for the stamp.
I guess you could also use pulsed input from 1/2 of the AC (as you would do
with the opto-isolator) and have the stamp program check for the pulses in
your loop. Of course, this depends upon what else your program is doing and
how long the loop is in comparison with your AC frequency.
If you want to optically isolate this with RS parts, ping the list for
Rodent, who has experience with combining discrete emitters and detectors.
Chris
>
> I need to detect the presence/absence of 24VAC on a line with a Stamp
> PIO. Can anyone tell me how to do this cheaply? I looked for a
> 24VAC coil relay at the local electronics store, but couldn't find
> one.
>
> /John
>
>
> To UNSUBSCRIBE, just send mail to:
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> http://docs.yahoo.com/info/terms/
>
>
Original Message
> I need to detect the presence/absence of 24VAC on a line with a Stamp
> PIO. Can anyone tell me how to do this cheaply? I looked for a
> 24VAC coil relay at the local electronics store, but couldn't find
> one.
ive attached a small schematic, the values are rough, some might need
adjustment.
normdoty@h...
>From: "johnschwab5678" <johnschwab5678@y...>
>Reply-To: basicstamps@yahoogroups.com
>To: basicstamps@yahoogroups.com
>Subject: [noparse][[/noparse]basicstamps] VAC detection
>Date: Sat, 02 Mar 2002 21:12:58 -0000
>
>I need to detect the presence/absence of 24VAC on a line with a Stamp
>PIO. Can anyone tell me how to do this cheaply? I looked for a
>24VAC coil relay at the local electronics store, but couldn't find
>one.
>
>/John
>
>
>To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
>from the same email address that you subscribed. Text in the Subject and
>Body of the message will be ignored.
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp.
[noparse][[/noparse]Non-text portions of this message have been removed]
attached as a .pdf file
The circuit uses resistors, a diode bridge, capacitor, and an optoisolator.
If you want to build the 24 volt only version, you cam omit the 2 10k 10 Watt
resistors. The cost then will be less than $5 in parts.
I use this circuit in many industrial applications and it works well.
Solid State input modules also work, but they cost around $10 and will do 24
to 120 Volts but they are AC or DC, not both.
Hope this helps,
Alan Bradford
Plasma Technologies
[noparse][[/noparse]Non-text portions of this message have been removed]
It seems the attached pdf file will not go along with the e-mail to the list.
Cut and past also does not work.
If you will send me a e-mail direct, not from the yahoo group then I will
send you back the pdf file.
Put "Direct Contact" in the subject line, as I sometimes get busy and only
skim the list files. It may take a day or too to respond but I will send it
to all who are interested.
Alan Bradford,
Plasma Technologies
plasmastamp@a...
If you go to http://groups.yahoo.com/group/basicstamps you'll see a link
for "Files" - This is a great place to upload stuff like this.
Al Williams
AWC
* 8 channels of PWM
http://www.al-williams.com/awce/pak5.htm
>
Original Message
> From: plasmastamp@a... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=QYKbV3boJToDamw0ifV1xSs6W0mU0Uc_s4mgn0M5SKHGH50nM6Eq47QyWsXuPU911fItjlOBFHknpy8s]plasmastamp@a...[/url
> Sent: Monday, March 04, 2002 7:28 AM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] VAC detection
>
>
> Hi All,
>
> It seems the attached pdf file will not go along with the
> e-mail to the list. Cut and past also does not work.
>
> If you will send me a e-mail direct, not from the yahoo group
> then I will
> send you back the pdf file.
>
> Put "Direct Contact" in the subject line, as I sometimes get
> busy and only
> skim the list files. It may take a day or too to respond but
> I will send it
> to all who are interested.
>
> Alan Bradford,
> Plasma Technologies
> plasmastamp@a...
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
I went to the site you listed and did not see any way to upload the file. I
tried registering and signing in but still no luck. Im sure Im doing some
simple and wrong. Stamps are sometimes easier than the Internet.
I am sending the file to you. Could you post it on the site for me.
Thanks,
Alan Bradford
Plasma Technologies
[noparse][[/noparse]Non-text portions of this message have been removed]
A few weeks ago, I had just the same problem with Yahoo.
It was never solved and I still can not post files.
Sorry for the members of the list.
ECO
Original Message
From: <plasmastamp@a...>
To: <basicstamps@yahoogroups.com>
Sent: Tuesday, March 05, 2002 7:48 PM
Subject: Re: [noparse][[/noparse]basicstamps] VAC detection
>
> Hi Al,
>
> I went to the site you listed and did not see any way to upload the file. I
> tried registering and signing in but still no luck. Im sure Im doing some
> simple and wrong. Stamps are sometimes easier than the Internet.
>
> I am sending the file to you. Could you post it on the site for me.
>
> Thanks,
> Alan Bradford
> Plasma Technologies
First I went here: http://groups.yahoo.com/group/basicstamps/
You may need to sign in if you don't stay signed in.
So click Sign In to Yahoo and enter your credentials.
Then click on Files on the left-hand side navigation bar. The bar reads:
Home, Messages, Post, Chat, Files.... You want Files
Near the top of the resulting page, click Add File
Enter the local file name in the top field (or use the browse button).
You have to specify the whole path (c:\my pictures\xyz.gif).
Put a description in the second box. Check Notification if you want
everyone to get an email saying you put the file in there.
Press Upload file.
That's it! Should work for everyone, I think.
Al Williams
AWC
* Floating point math for the Stamp, PIC, SX, or any microcontroller
http://www.al-williams.com/awce/pak1.htm
>
Original Message
> From: ECO [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=4crkNbPS4s3CWLeedn_tUm3Cz5hDjZVrgVa7cTM_d2FHrLG3TVtn-Q_W8nRIr-v_z2NsB-9OCT7OiA]ecourt@b...[/url
> Sent: Wednesday, March 06, 2002 3:48 AM
> To: basicstamps@yahoogroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] VAC detection
>
>
> Alan
> A few weeks ago, I had just the same problem with Yahoo.
> It was never solved and I still can not post files.
> Sorry for the members of the list.
> ECO
>
Original Message
> From: <plasmastamp@a...>
> To: <basicstamps@yahoogroups.com>
> Sent: Tuesday, March 05, 2002 7:48 PM
> Subject: Re: [noparse][[/noparse]basicstamps] VAC detection
>
>
> >
> > Hi Al,
> >
> > I went to the site you listed and did not see any way to upload the
> > file. I
> > tried registering and signing in but still no luck. Im sure
> Im doing some
> > simple and wrong. Stamps are sometimes easier than the Internet.
> >
> > I am sending the file to you. Could you post it on the site for me.
> >
> > Thanks,
> > Alan Bradford
> > Plasma Technologies
>
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
Here is a parts list for the AC/DC Input file posted to the Basic Stamps file
area 24Input.pdf
The Capacitor C1 can be changed to 3300pf if the on to off state needs to
happen faster. This cap is there to smooth out the AC ripple that can cause
the stamp input to pulse at 60 (or 50) Hz line frequency.
R1 A&B only need to be 5 watt units and if not using 120 volts can be
omitted.
As always when using high voltage circuits be very cautious of your wiring,
and use fused circuits for the inputs.
Parts List
BR1 1 Amp 1000 PIV Diode Bridge DIP Package Lower PIV rating can be used but
for good reliability on a 120 VAC line
1000 PIV recommended
C1 3300 pf 50 VDC Disc Capacitor
R1 A&B 10k Ohm 5 Watt Resistor Only required if using 120 Volt
input.
R2 1k Ohm 2 Watt Resistor Only Required if using 24 Volt Input.
R3 470 Ohm ¼ Watt Resistor
R4 100k Ohm ¼ Watt Resistor
U1 4N32 Short Optoisolator Toshiba Darlington Transistor Output
Sorry for omitting this info on the print. That was an internal use print and
I take lots of things for granted.
Thank You,
Alan Bradford
Plasma Technologies