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Author Topic: "ON THE AIR" sign  (Read 1499 times)
KE5EKO
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Posts: 22




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« on: March 03, 2008, 11:50:46 AM »

I overheard a QSO the other day and the subject was this sign. Before I could copy any information regarding a source of supply, the signals were gone. From what I understood, this sign requires no hard-wiring. I guess it operates via stray RF. Anyone have any ideas where one of these signs could be purchased or better yet, where plans could be obtained to build one ??  Thanks...Mike.....
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WB2WIK
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Posts: 20545




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« Reply #1 on: March 03, 2008, 02:28:52 PM »

Building one is easy, if you don't mind making the sign itself.  You could use incandescent lamps, LEDs, etc.  -- I'd stay away from low voltage Halogens and low voltage fluoroescents because they tend to generate RF noise you can hear in receivers.

All you need is a circuit to sense RF and close a relay.  What you do with the relay terminals is up to you!

A sensitive detector driving a current amplifier driving a relay will work for FM or RTTY (and maybe AM) but won't work for SSB or CW because it will constantly clack on and off with modulation or sending.  So you might want a circuit with a time-delay for relay "dropout," to keep the sign lit up between syllables and words for those modes.

I'd be happy to draw you a circuit diagram but this website makes it really hard to draw anything.  Just search "Carrier Operated Relay" or "Carrier Operated Switch" and you'll find tons of circuits.  It can be built using a small handful of parts (powered by your station 12V power supply to provide power for those parts and the relay) but then "activated" by only RF, which is what you want.

WB2WIK/6
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KE5EKO
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Posts: 22




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« Reply #2 on: March 03, 2008, 03:57:59 PM »

I found the company that made them but they were discontinued back in 2001. I did numerous searches for "carrier operated switch" and "carrier operated relay" but all I came across was definitions, switch mfgs and ever carrier pigions......so If you would draw a diagram for me, that would be great. You could e-mail it to me. My e-mail address is listed on this site with my call info. I have a general idea of what I need but I'm not 100% sure.....Thanks.....Mike
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WB2WIK
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Posts: 20545




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« Reply #3 on: March 05, 2008, 01:10:16 PM »

Took me about two seconds to find a suitable circuit on line, here:

http://books.google.com/books?id=cVDL2GjXOKUC&pg=PA71&lpg=PA71&dq=%22RF+actuated+switch%22&source=web&ots=m8KvBz7G_K&sig=wIo1RNZ9vbKgPMjb_rpOfgLcHms&hl=en

Look at Figure 9-12.  Build it, that's it.

73

Steve WB2WIK/6
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W0FM
Member

Posts: 2052




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« Reply #4 on: March 07, 2008, 11:20:27 AM »

Hi,

I built this WavPro LED Kit.  It scrolls your Call Sign, does temperature, date, etc. and has an "On Air" sensor built in.  It was a fun and useful project and not at all difficult to assemble.

http://www.eham.net/reviews/detail/6186


Build something and have fun!

73,

Terry, WØFM
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KE5EKO
Member

Posts: 22




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« Reply #5 on: March 07, 2008, 01:04:00 PM »

Thanks for the replies. Looks great......Mike
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KM5Z
Member

Posts: 24


WWW

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« Reply #6 on: June 24, 2008, 09:43:26 AM »

I built one from the QST article from 2004 - August I think it was:

Inside - a grid of red LEDs illuminate the
'ON AIR' inkjet printed on transparency
media

http://picasaweb.google.com/mikeyancey/ElectronicProjects/photo#5186768918630832450

Outsite - the red translucent window -
made from a scrap of a red plastic notebook!

http://picasaweb.google.com/mikeyancey/ElectronicProjects/photo#5041901649901784210

Outside Closeup - PTT activates it; on SSB
it'll hold for a second or so between peaks

http://picasaweb.google.com/mikeyancey/ElectronicProjects/photo#5187095671152777554

73 - and happy solder-smoke...
Mike Yancey
KM5Z
Dallas, Texas
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