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Author Topic: Eico EC 1000 cw oscillator  (Read 2177 times)
3B8CF
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Posts: 4




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« on: March 24, 2009, 07:21:40 PM »

Hello Group,
 I just came across  my Eico code osc which I built back from a kit  in 1967 while learning  morse to get my licence. I tried it but it does not work.
 It is a simple circuit with 2 transistors ,one resistor and a ceramic capacitor.
I have checked both transistors and both are faulty. Does any one still have the circuit diagram for it or still remember which type of transistors were used.  One is a big one like the 2N3055 ( TO 203), may be PNP  and the other is a amaller metal can type , like the 2n3053(TO 205). I tried Google but was unsuccessful.
 I can build a newer version with the 555 timer , but I want to get this one working as it brings back lots of nice memories to me.
 Thanks
 Jacky 3B8CF


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KC8KNM
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« Reply #1 on: June 16, 2009, 08:58:10 AM »

Hi Jacky, I just picked up an ec 1000 oscillator and tone board on ebay a week ago and its in working condition.  I'll check to see if there are any markings on the cans of the transistors.
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WA9UAA
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« Reply #2 on: June 16, 2009, 09:28:25 AM »

Hope you can get the transistorized unit working, any oscillator I built with a 555 sounded terrible. Running the output of the 555 oscillator through a 1:1 audio transformer might help a bit; though I never tried it.
73,
Rob WA9UAA
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KC8KNM
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« Reply #3 on: June 18, 2009, 06:10:59 AM »

Hi Jacky, are you still out there?  I checked the cans for the transistors and there's no markings at all.  I would guess they rubbed off somewhere in the 70's.  The kit I have has not only the oscillator but an amp board too that drives a speaker.  There's also a buzzer hooked up to it but I think that might have been added after the build and wasn't originally part of the oscillator kit.
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KA5N
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« Reply #4 on: June 18, 2009, 08:21:42 AM »

Back in the 1960's PNP transistors were much more plentiful than NPN types.  I found a schematic for an Eico 706 CP osc and it used a single PNP with in a relaxation circuit.  I suspect that the EC 1000 uses a similar circuit with a larger PNP for an amp.  The specs of the transistors for such a simple non-critical application don't much matter.  Just about any type that meet the power requirements should work.
Another thing that could be done since today NPN's are readily available is use a couple of them and reverse the power leads (and of course the polarity of any electrolytic caps in the circuit).
Junk box, here we come.
Allen
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WB0IXV
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« Reply #5 on: June 18, 2009, 08:53:54 AM »

You might check out the Code Oscillator Museum at:
http://www.n4mw.com/cpo.htm

They have an Eico EC1000:
http://www.n4mw.com/cp114.htm

If you contact him, he may open the box and see what the schematic says they are!
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KC8KNM
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« Reply #6 on: January 22, 2010, 05:27:26 PM »

Score!  I contacted Dave N4MW and he was kind enough to send me a scanned copy of the docs on the ec-1000.  The one that I had was wired up with another board EC-300 but once I removed that and re-connected the EC-1000 per the diagram, the tone was beautiful!  I don't have a lot of time listening to 555 timer based oscillators but I can say that this is a very smooth tone.  It's unbelievably simple too.  For anyone interested, here's the parts list

100k resistor
.01 uf capacitor
npn transistor
pnp power transistor

And now to find a good key!
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