Morse Code Audio Tape to Sounder

Sensacell

Joined Jun 19, 2012
2,452
Looks like a good circuit, it should work.

The diode D1 is in the wrong place, should be placed across the sounder, not the transistor.

Start building!
 
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Thread Starter

KB3TZB

Joined Feb 9, 2018
10
Looks like a good circuit, it should work.

The diode D1 is in the wrong place, should be placed across the sounder, not the transistor.

Start building!
I have rebuilt this circuit several times with limited success, including the modification you suggested. With a 2N2222 in place of the TIP 31 it worked at the museum for two weeks, then failed. I have a working telegraph relay that I can drive with 540 mWatts. I measure the tape output at 0.8 mWatts. I am looking for a 28 dB amplifier to power the relay. The relay works the sounder fine when the proper power is applied. A power amplifier circuit will be much appreciated. Regards, Morgan
 

AnalogKid

Joined Aug 1, 2013
8,150
3 V and 20 ohms works out to 150 mA. That's a bit high for a 2N2222 (2N3904, 2N4401, etc.). If it is not being driven into firm saturation, death after 2 weeks might be due to overheating. Try the same circuit with the TIP31 (note the pinout difference). No heatsink necessary, the larger package should suffice.

ak
 
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MaxHeadRoom

Joined Jul 18, 2013
19,192
--- -.-
You might also get away with a modern alternative, a 2n7000 fet.
Does the Russian news agency TASS still broadcast in Morse, we used to use it for practice, tape derived morse at exactly 20wpm.
Max.
 

Thread Starter

KB3TZB

Joined Feb 9, 2018
10
--- -.-
You might also get away with a modern alternative, a 2n7000 fet.
Does the Russian news agency TASS still broadcast in Morse, we used to use it for practice, tape derived morse at exactly 20wpm.
Max.
What frequency does TASS broadcast on? I have an old Hallicrafters S20R that can probably pick it up. Thank you.
3 V and 20 ohms works out to 150 mA. That's a bit high for a 2N2222 (2N3904, 2N4401, etc.). If it is not being driven into firm saturation, death after 2 weeks might be due to overheating. Try the same circuit with the TIP31 (note the pinout difference). No heatsink necessary, the larger package should suffice.

ak
I am testing the same circuit with a TIP31. With a tone tape input the resistance between the emitter and the collector at the TIP 31 is zero, but for some reason the sounder doesn't operate. Testing just the three volt sounder circuit, shorting out the collector-emitter leads works fine...Thank you for the advice.
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MaxHeadRoom

Joined Jul 18, 2013
19,192
What frequency does TASS broadcast on? I have an old Hallicrafters S20R that can probably pick it up. Thank you.
Whoa, we are talking 1957-8 training with The Royal Signals, We actually picked up the announcement of the Sputnik launch!.
I suspect they are still using the same freq., Interesting to know if they still do.
I ended up in Tripoli where we had a registered Amateur Radio station and we were kept up all night requesting QSL , particularly from the U.S. as there were only two Libya call signs at that time that we knew of.
Max.
 

Thread Starter

KB3TZB

Joined Feb 9, 2018
10
Whoa, we are talking 1957-8 training with The Royal Signals, We actually picked up the announcement of the Sputnik launch!.
I suspect they are still using the same freq., Interesting to know if they still do.
I ended up in Tripoli where we had a registered Amateur Radio station and we were kept up all night requesting QSL , particularly from the U.S. as there were only two Libya call signs at that time that we knew of.
Max.
Thank you Max...I was a sophomore in high school in 1957.
 
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