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SCR info needed for sound activated light Morse Code

I need to transform audio morse code into flashing light morse code.

My goal is to drive a light bulb to flash morse code from an audio speaker level source output. (cassette player).

My grasp of the use of SCR's is very limited, but I was thinking of using a

12.6v filament transformer in series with an SCR and a light bulb, then use the audio output (external speaker) from a small cassette player to drive the gate of the SCR. I am assuming the gate will detect the audio and drive the scr junction into conduction to light the bulb visually displaying the dots and dashes as flashing light. What general use SCR available at Radio Shack might work in this application.

Any help appreciated.

thanks,

Vin Collins

Reply to
Vin Collins
Loading thread data ...

--
Excellent description of what you want to do, and I can't see any
reason why it won't work, but I'd go for a TRIAC instead of an SCR
in order to get both halves of the 60Hz to drive the lamp.

Unfortunately, I can't help you with what RS has in stock, since a
search for "TRIAC" on their site goes basically nowhere.

The good news is you should be able to use pretty much any TRIAC you
can find as long as it can handle the lamp current and your cassette
player can supply the current to turn it on.

The bad news is...
Oh, wait... there isn't any bad news.

Your filament transformer will provide isolation from the mains, and
as long as your cassette player's got the guts and the TRIAC can be
fired in all four quadrants, you're home, free.

:-)
Reply to
John Fields

Look for a VOX circuit, normally used for such functions as operating a transmitter PTT upon audio being present. Use it's output instead to drive a relay (solid-state or not) and then a light bulb.

Here's a starter, but by no means the only circuit around:

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Cheers.

Ken

Reply to
Ken Taylor

On Wed, 22 Feb 2006 16:29:42 -0600 in sci.electronics.basics, John Fields wrote,

Radio Shack has some Solid State Relay modules that I'd prefer for the isolation.

Reply to
David Harmon 

--
The problem with that, and most other VOX circuits, is that they
decay too slowly and, consequently, dah-di-dah gets smeared into
dahhhhhhhhhh.
Reply to
John Fields 

--
Since he'll be using a filament transformer to drive the lamp he'll
already have adequate isolation from the mains, plus there's (maybe)
the issue of driving the relay with AC.

In any case, I went to their site and couldn't find any solid-state
relays.  Got a link?
Reply to
John Fields

John Fields wrote in sci.electronics.design:

Even if it didn't, if the audible signal is anywhere near typical morse speed, the eye won't be able to follow. Optical morse signalling is *much* slower than acoustic.

Anno

--
If you want to post a followup via groups.google.com, don't use
the broken "Reply" link at the bottom of the article.  Click on 
"show options" at the top of the article, then click on the 
"Reply" at the bottom of the article headers.
Reply to
Anno Siegel

If you were able to use an LED as the flasher, things could become

*much* less complicated... 
--
St. John
Your analyst has you mixed up with another patient.  Don't believe a
thing he tells you.
Reply to
St. John Smythe

On Thu, 23 Feb 2006 06:35:51 -0600 in sci.electronics.basics, John Fields wrote,

You're right.

I saw them in bubble packs hanging from a hook. But maybe that was too far in the past. I couldn't find links to the triacs or SCRs either.

Reply to
David Harmon

Hi Vin,

: My goal is to drive a light bulb to flash morse code from : an audio speaker level source output. (cassette player).

We used to do this quite a bit (way back when). The circuit takes speaker level audio and fires and AC Lamp. It is/was called a "color organ' circuit.

: My grasp of the use of SCR's is very limited, but I was : thinking of using a 12.6v filament transformer in series with : an SCR and a light bulb, then use the audio output (external : speaker) from a small cassette player to drive the gate of the : SCR.

First let me tell you I've built the circuit way back when in the 1970's. The SCR will cause a pop noise in the audio when the scr switches on. Way back when we were never able to get the pop noise out of using the color organ circuit with an AM Radio speaker audio driving it. FM Radio was pretty much ok.

So you'd want to try and use an SCR or Triac Type of device with an AC waveform zero cross detection/switching circuit. You can actually find newer scr/triacdevices, which switch only on the ac line voltage zero cross point.

: I am assuming the gate will detect the audio and drive the : scr junction into conduction to light the bulb visually : displaying the dots and dashes as flashing light.

The color organ circuits I built had frequency ranges for each of the 3 scrs, one bass, one mid-range and the last for high frequency audio. If you're using it for CW notes, the mid range audio filter & gate driver circuit would be set up to best respond and detect about 750Hz audio.

: What general use SCR available at Radio Shack might work in : this application. : Any help appreciated. : thanks, : Vin Collins

Pretty much any scr they sell if you plan to use only a 12 volt transformer.

I took a quick peek over on Ebay to see if anyone had vintage color organ kits for sale. There is a guy selling what looks like the same 3 channel circuit I built back in the 70's from a magazine. One seller is Hobbytron so I went to see if they also sold on the web.

I'm sure if you search google for color organ circuits, you'll find some example circuits. I located hobbytron.com ... they seem to sell kits, which might be just what you want.

They had a 3 channel color organ kit for about $29 When I searched "color organ" on their main home page I saw they also have a single channel color organ kit for $9.95 The single channel kit has the parts and pc board to get going if you'd like to go that direction.

Good luck,

cheers, skipp

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Reply to
Skipp from the radiowrench son

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