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Morse code flasher

G

Gavin Philpott

Jan 1, 1970
0
Hello,

I'm trying to make a device that can convert a Morse code audio file to a
flashing light. I have the Morse message recorded as a music CD consisting
of 800Hz tone for the dots & dashes & silence for the spaces. I want to be
able to convert the audio output from the CD player to an on/off signal that
I can use to flash a light. (the idea being that I can 'flash' a message by
pressing play - this is to be used to repeatedly transmit the same message
to a several groups of Scouts on a hike).

I have tried using an LM2719 frequency to voltage converter to discriminate
between tone & silence but without success.

Any ideas gratefully received.

Gavin.
 
Gavin said:
Hello,

I'm trying to make a device that can convert a Morse code audio file to a
flashing light. I have the Morse message recorded as a music CD consisting
of 800Hz tone for the dots & dashes & silence for the spaces. I want to be
able to convert the audio output from the CD player to an on/off signal that
I can use to flash a light. (the idea being that I can 'flash' a message by
pressing play - this is to be used to repeatedly transmit the same message
to a several groups of Scouts on a hike).

I have tried using an LM2719 frequency to voltage converter to discriminate
between tone & silence but without success.

Any ideas gratefully received.

Gavin.

If the CD doesn't have any serious S/N problems, a plain old comparator
like an LM311 should do just fine. The only catch is you might want to
use a retriggerable monostable to convert the 800 hz pulse train to
just the envelope and then a simple transistor driver to your LED. It
would work OK without the MMV though.

GG
 
E

ehsjr

Jan 1, 1970
0
Gavin said:
Hello,

I'm trying to make a device that can convert a Morse code audio file to a
flashing light. I have the Morse message recorded as a music CD consisting
of 800Hz tone for the dots & dashes & silence for the spaces. I want to be
able to convert the audio output from the CD player to an on/off signal that
I can use to flash a light. (the idea being that I can 'flash' a message by
pressing play - this is to be used to repeatedly transmit the same message
to a several groups of Scouts on a hike).

I have tried using an LM2719 frequency to voltage converter to discriminate
between tone & silence but without success.

Any ideas gratefully received.

Gavin.

Many years ago I used something like this
on the output of a tape player (with a relay
instead of the LED) to key my transmitter
to call CQ. It may be as simple for you.


+V ---[R]---[LED]--------+
|
/c
Audio out --->|---[C]---| NPN
\e
|
Gnd ----------------------+


Size R to keep LED current to ~ 20 mA at
whatever your V is.

If a LED is not good and you need a higher
current lamp, use something like a TIP 120
instead of the generic NPN and remove R.
You'll need a heatsink on the transistor
if you go above 2W in it.

Ed
 
J

John Fields

Jan 1, 1970
0
Gavin said:
Hello,

I'm trying to make a device that can convert a Morse code audio file to a
flashing light. I have the Morse message recorded as a music CD consisting
of 800Hz tone for the dots & dashes & silence for the spaces. I want to be
able to convert the audio output from the CD player to an on/off signal that
I can use to flash a light. (the idea being that I can 'flash' a message by
pressing play - this is to be used to repeatedly transmit the same message
to a several groups of Scouts on a hike).

I have tried using an LM2719 frequency to voltage converter to discriminate
between tone & silence but without success.

Any ideas gratefully received.

Gavin.

Many years ago I used something like this
on the output of a tape player (with a relay
instead of the LED) to key my transmitter
to call CQ. It may be as simple for you.


+V ---[R]---[LED]--------+
|
/c
Audio out --->|---[C]---| NPN
\e
|
Gnd ----------------------+


Size R to keep LED current to ~ 20 mA at
whatever your V is.

If a LED is not good and you need a higher
current lamp, use something like a TIP 120
instead of the generic NPN and remove R.
You'll need a heatsink on the transistor
if you go above 2W in it.

---
With the audio output from the CD player probably being cap coupled
and with no DC return for your cap, I'm pretty sure that won't work.

This might:

+V
|
[LAMP]
|
C
AUDIO>---+-----[1K]--+----B NPN
|K | E DARLINGTON
[1N4148] [10K] |
| | |
GND>-----+-----------+------+

The premise being that due to the thermal inertia of the lamp
filament (or the persistence of human vision) the dead time between
the 400Hz positive half-cycles doing the work won't be noticed.

The 1N4148 is just to make sure the negative half-cycles don't get a
chance to excessively reverse-bias the B-E B-E junctions of the
Darlington, but with them being in series and the audio from the CD
plaver not likely to be more than a couple of volts, it can probably
be eliminated.

Thinking about the [low-level] audio out from the CD, though, this
might be a better scheme, assuming a 12V supply and a fairly hefty
incandescent lamp load:

+12V>---------------+-------------------+
| |
[1000] |
| S
+----------+------G IRF5210
| | D
C | |
AUDIO>--[1K]--+---B 2N3904 |K |
| E [1N5245] [LAMP]
[10K] | | |
| | | |
GND>----------+-----+----------+--------+
 
E

ehsjr

Jan 1, 1970
0
John said:
Gavin said:
Hello,

I'm trying to make a device that can convert a Morse code audio file to a
flashing light. I have the Morse message recorded as a music CD consisting
of 800Hz tone for the dots & dashes & silence for the spaces. I want to be
able to convert the audio output from the CD player to an on/off signal that
I can use to flash a light. (the idea being that I can 'flash' a message by
pressing play - this is to be used to repeatedly transmit the same message
to a several groups of Scouts on a hike).

I have tried using an LM2719 frequency to voltage converter to discriminate
between tone & silence but without success.

Any ideas gratefully received.

Gavin.

Many years ago I used something like this
on the output of a tape player (with a relay
instead of the LED) to key my transmitter
to call CQ. It may be as simple for you.


+V ---[R]---[LED]--------+
|
/c
Audio out --->|---[C]---| NPN
\e
|
Gnd ----------------------+


Size R to keep LED current to ~ 20 mA at
whatever your V is.

If a LED is not good and you need a higher
current lamp, use something like a TIP 120
instead of the generic NPN and remove R.
You'll need a heatsink on the transistor
if you go above 2W in it.


---
With the audio output from the CD player probably being cap coupled
and with no DC return for your cap, I'm pretty sure that won't work.

This might:

+V
|
[LAMP]
|
C
AUDIO>---+-----[1K]--+----B NPN
|K | E DARLINGTON
[1N4148] [10K] |
| | |
GND>-----+-----------+------+

The premise being that due to the thermal inertia of the lamp
filament (or the persistence of human vision) the dead time between
the 400Hz positive half-cycles doing the work won't be noticed.

The 1N4148 is just to make sure the negative half-cycles don't get a
chance to excessively reverse-bias the B-E B-E junctions of the
Darlington, but with them being in series and the audio from the CD
plaver not likely to be more than a couple of volts, it can probably
be eliminated.

Thinking about the [low-level] audio out from the CD, though, this
might be a better scheme, assuming a 12V supply and a fairly hefty
incandescent lamp load:

+12V>---------------+-------------------+
| |
[1000] |
| S
+----------+------G IRF5210
| | D
C | |
AUDIO>--[1K]--+---B 2N3904 |K |
| E [1N5245] [LAMP]
[10K] | | |
| | | |
GND>----------+-----+----------+--------+

Nice - he could flash morse on his car's headlights with that!
*Far* better than the TIP 120 I mentioned.

As I recall, the audio level was a problem, of sorts. I had to
crank the volume of the tape player up pretty high before the
circuit would respond.

Regarding the thermal inertia, that's true, but I don't think
you'd see the blink, even if you use an LED. I don't *know*
how high the frequency would have to be before persistence of
vision prevents you from seeing the blink, but I'd bet it is
well below 400 Hz.

The original circuit ought to work, though. The DC return is
through be to ground.

Ed
 
J

John Fields

Jan 1, 1970
0
John said:
Gavin Philpott wrote:

Hello,

I'm trying to make a device that can convert a Morse code audio file to a
flashing light. I have the Morse message recorded as a music CD consisting
of 800Hz tone for the dots & dashes & silence for the spaces. I want to be
able to convert the audio output from the CD player to an on/off signal that
I can use to flash a light. (the idea being that I can 'flash' a message by
pressing play - this is to be used to repeatedly transmit the same message
to a several groups of Scouts on a hike).

I have tried using an LM2719 frequency to voltage converter to discriminate
between tone & silence but without success.

Any ideas gratefully received.

Gavin.



Many years ago I used something like this
on the output of a tape player (with a relay
instead of the LED) to key my transmitter
to call CQ. It may be as simple for you.


+V ---[R]---[LED]--------+
|
/c
Audio out --->|---[C]---| NPN
\e
|
Gnd ----------------------+


Size R to keep LED current to ~ 20 mA at
whatever your V is.

If a LED is not good and you need a higher
current lamp, use something like a TIP 120
instead of the generic NPN and remove R.
You'll need a heatsink on the transistor
if you go above 2W in it.


---
With the audio output from the CD player probably being cap coupled
and with no DC return for your cap, I'm pretty sure that won't work.

This might:

+V
|
[LAMP]
|
C
AUDIO>---+-----[1K]--+----B NPN
|K | E DARLINGTON
[1N4148] [10K] |
| | |
GND>-----+-----------+------+

The premise being that due to the thermal inertia of the lamp
filament (or the persistence of human vision) the dead time between
the 400Hz positive half-cycles doing the work won't be noticed.

The 1N4148 is just to make sure the negative half-cycles don't get a
chance to excessively reverse-bias the B-E B-E junctions of the
Darlington, but with them being in series and the audio from the CD
plaver not likely to be more than a couple of volts, it can probably
be eliminated.

Thinking about the [low-level] audio out from the CD, though, this
might be a better scheme, assuming a 12V supply and a fairly hefty
incandescent lamp load:

+12V>---------------+-------------------+
| |
[1000] |
| S
+----------+------G IRF5210
| | D
C | |
AUDIO>--[1K]--+---B 2N3904 |K |
| E [1N5245] [LAMP]
[10K] | | |
| | | |
GND>----------+-----+----------+--------+

Nice - he could flash morse on his car's headlights with that!
*Far* better than the TIP 120 I mentioned.

As I recall, the audio level was a problem, of sorts. I had to
crank the volume of the tape player up pretty high before the
circuit would respond.

Regarding the thermal inertia, that's true, but I don't think
you'd see the blink, even if you use an LED. I don't *know*
how high the frequency would have to be before persistence of
vision prevents you from seeing the blink, but I'd bet it is
well below 400 Hz.

The original circuit ought to work, though. The DC return is
through be to ground.

---
The problem is with the other end of the cap, which has no discharge
path. Essentially what you have is a charge pump, and as the
capacitor accumulates charge the voltage across it will build up and
let less and less of the input signal through to the transistor.

Run this to see it in action:)

Version 4
SHEET 1 880 680
WIRE -464 320 -464 256
WIRE -464 448 -464 400
WIRE -432 256 -464 256
WIRE -320 256 -352 256
WIRE -320 256 -320 112
WIRE -320 320 -320 256
WIRE -320 448 -464 448
WIRE -320 448 -320 400
WIRE -272 448 -320 448
WIRE -272 448 -272 384
WIRE -176 112 -320 112
WIRE -128 336 -272 336
WIRE -128 352 -128 336
WIRE -128 448 -272 448
WIRE -128 448 -128 432
WIRE -16 112 -112 112
WIRE 128 112 48 112
WIRE 192 -64 192 -96
WIRE 192 64 192 16
WIRE 192 448 -128 448
WIRE 192 448 192 160
WIRE 352 -96 192 -96
WIRE 352 320 352 -96
WIRE 352 448 192 448
WIRE 352 448 352 400
WIRE 352 496 352 448
FLAG 352 496 0
SYMBOL npn 128 64 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL res 176 -80 R0
SYMATTR InstName R1
SYMATTR Value 1000
SYMBOL diode -176 128 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL cap 48 96 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C1
SYMATTR Value 1e-6
SYMBOL voltage -464 304 R0
WINDOW 3 24 104 Invisible 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value SINE(0 5 800)
SYMBOL voltage 352 304 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 12
SYMBOL sw -320 416 R180
WINDOW 0 -51 99 Left 0
WINDOW 3 -91 128 Left 0
SYMATTR InstName S2
SYMATTR Value MYSW
SYMBOL voltage -128 336 R0
WINDOW 3 24 104 Invisible 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value PULSE(0 1 0 0 0 .05 .1)
SYMBOL res -336 240 R90
WINDOW 0 -40 55 VBottom 0
WINDOW 3 -36 56 VTop 0
SYMATTR InstName R2
SYMATTR Value 100
TEXT -402 506 Left 0 !.tran 0 1 0
TEXT -400 552 Left 0 !.model MYSW SW(Ron=1 Roff=1Meg Vt=0.5 Vh=0)
 
E

ehsjr

Jan 1, 1970
0
John said:
John said:
Gavin Philpott wrote:


Hello,

I'm trying to make a device that can convert a Morse code audio file to a
flashing light. I have the Morse message recorded as a music CD consisting
of 800Hz tone for the dots & dashes & silence for the spaces. I want to be
able to convert the audio output from the CD player to an on/off signal that
I can use to flash a light. (the idea being that I can 'flash' a message by
pressing play - this is to be used to repeatedly transmit the same message
to a several groups of Scouts on a hike).

I have tried using an LM2719 frequency to voltage converter to discriminate
between tone & silence but without success.

Any ideas gratefully received.

Gavin.



Many years ago I used something like this
on the output of a tape player (with a relay
instead of the LED) to key my transmitter
to call CQ. It may be as simple for you.


+V ---[R]---[LED]--------+
|
/c
Audio out --->|---[C]---| NPN
\e
|
Gnd ----------------------+


Size R to keep LED current to ~ 20 mA at
whatever your V is.

If a LED is not good and you need a higher
current lamp, use something like a TIP 120
instead of the generic NPN and remove R.
You'll need a heatsink on the transistor
if you go above 2W in it.


---
With the audio output from the CD player probably being cap coupled
and with no DC return for your cap, I'm pretty sure that won't work.

This might:

+V
|
[LAMP]
|
C
AUDIO>---+-----[1K]--+----B NPN
|K | E DARLINGTON
[1N4148] [10K] |
| | |
GND>-----+-----------+------+

The premise being that due to the thermal inertia of the lamp
filament (or the persistence of human vision) the dead time between
the 400Hz positive half-cycles doing the work won't be noticed.

The 1N4148 is just to make sure the negative half-cycles don't get a
chance to excessively reverse-bias the B-E B-E junctions of the
Darlington, but with them being in series and the audio from the CD
plaver not likely to be more than a couple of volts, it can probably
be eliminated.

Thinking about the [low-level] audio out from the CD, though, this
might be a better scheme, assuming a 12V supply and a fairly hefty
incandescent lamp load:

+12V>---------------+-------------------+
| |
[1000] |
| S
+----------+------G IRF5210
| | D
C | |
AUDIO>--[1K]--+---B 2N3904 |K |
| E [1N5245] [LAMP]
[10K] | | |
| | | |
GND>----------+-----+----------+--------+

Nice - he could flash morse on his car's headlights with that!
*Far* better than the TIP 120 I mentioned.

As I recall, the audio level was a problem, of sorts. I had to
crank the volume of the tape player up pretty high before the
circuit would respond.

Regarding the thermal inertia, that's true, but I don't think
you'd see the blink, even if you use an LED. I don't *know*
how high the frequency would have to be before persistence of
vision prevents you from seeing the blink, but I'd bet it is
well below 400 Hz.

The original circuit ought to work, though. The DC return is
through be to ground.


---
The problem is with the other end of the cap, which has no discharge
path. Essentially what you have is a charge pump, and as the
capacitor accumulates charge the voltage across it will build up and
let less and less of the input signal through to the transistor.

Run this to see it in action:)

Thanks!

It's not a pretty picture. Decays to very little in .9 S.
Disappears at 14 sec. It demonstrates your point, very well.

You have to use a bigger C1, but after a while the same
thing will happen. Maybe there is some combination of
duty cycle and cap leakage that works by accident, but
the circuit, such as it is, fails. I stuffed a 470
in the simulator and let it run for 50 seconds - it started
showing the decay between 20 and 30, and it was
pronounced between 40 and 50.

Is there a way to put a duty cycle in?

Ed
 
J

John Fields

Jan 1, 1970
0
Thanks!

It's not a pretty picture. Decays to very little in .9 S.
Disappears at 14 sec. It demonstrates your point, very well.

You have to use a bigger C1, but after a while the same
thing will happen. Maybe there is some combination of
duty cycle and cap leakage that works by accident, but
the circuit, such as it is, fails. I stuffed a 470
in the simulator and let it run for 50 seconds - it started
showing the decay between 20 and 30, and it was
pronounced between 40 and 50.

Is there a way to put a duty cycle in?

---
The easiest way out, I think, is just to get rid of the cap:

Version 4
SHEET 1 880 680
WIRE -624 192 -624 112
WIRE -624 320 -624 272
WIRE -624 448 -624 400
WIRE -480 112 -624 112
WIRE -480 320 -480 112
WIRE -480 448 -624 448
WIRE -480 448 -480 400
WIRE -432 448 -480 448
WIRE -432 448 -432 384
WIRE -352 112 -480 112
WIRE -288 336 -432 336
WIRE -288 352 -288 336
WIRE -288 448 -432 448
WIRE -288 448 -288 432
WIRE 16 112 -272 112
WIRE 16 240 16 112
WIRE 16 448 -288 448
WIRE 16 448 16 320
WIRE 128 112 16 112
WIRE 192 -64 192 -96
WIRE 192 64 192 16
WIRE 192 448 16 448
WIRE 192 448 192 160
WIRE 352 -96 192 -96
WIRE 352 320 352 -96
WIRE 352 448 192 448
WIRE 352 448 352 400
WIRE 352 496 352 448
FLAG 352 496 0
SYMBOL npn 128 64 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL res 176 -80 R0
SYMATTR InstName R1
SYMATTR Value 1000
SYMBOL voltage -624 304 R0
WINDOW 3 24 104 Invisible 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value SINE(0 1 100)
SYMATTR InstName V1
SYMBOL voltage 352 304 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 12
SYMBOL sw -480 416 R180
WINDOW 0 -51 99 Left 0
WINDOW 3 -91 128 Left 0
SYMATTR InstName S2
SYMATTR Value MYSW
SYMBOL voltage -288 336 R0
WINDOW 3 24 104 Invisible 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(0 1 0 0 0 .05 .1)
SYMATTR InstName V3
SYMBOL res -256 96 R90
WINDOW 0 -40 55 VBottom 0
WINDOW 3 -36 56 VTop 0
SYMATTR InstName R2
SYMATTR Value 100
SYMBOL res 0 224 R0
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL res -640 176 R0
SYMATTR InstName R3
SYMATTR Value 10
TEXT -402 506 Left 0 !.tran 0 1 0
TEXT -400 552 Left 0 !.model MYSW SW(Ron=1 Roff=1Meg Vt=0.5 Vh=0)


I set the generator output to +/- 1V to more closely simulate what's
going to be coming out of the CD player, and I made it look like it
has ~ 100 ohm resistive output impedance. If it's cap-coupled, in
reality, it won't make any difference because R4 will provide the
path to ground on one end and whatever's driving it in the CD player
will take care of the other end.

Seems to work pretty well...
 
R

Rich Grise

Jan 1, 1970
0
Hello,

I'm trying to make a device that can convert a Morse code audio file to a
flashing light. I have the Morse message recorded as a music CD consisting
of 800Hz tone for the dots & dashes & silence for the spaces. I want to be
able to convert the audio output from the CD player to an on/off signal
that I can use to flash a light. (the idea being that I can 'flash' a
message by pressing play - this is to be used to repeatedly transmit the
same message to a several groups of Scouts on a hike).

I have tried using an LM2719 frequency to voltage converter to
discriminate between tone & silence but without success.

Any ideas gratefully received.

Gavin.

Do you mean, you have a thing, with a speaker, that goes,
"BEEP-BI-BEEP-BIP, BEEP-BEEP-BI-BEEP" audibly?

If so it's almost trivial. Get an LED and a 220 ohm resistor, and put them
in series right directly across the speaker leads. Turn up the volume
until it's bright enough to suit you. :)

Good Luck!
Rich
 
G

Gavin Philpott

Jan 1, 1970
0
John, Ed,

Thanks both for your help with this; I'm off to try it out. Couldn't make
head or tail of the circuits for a start, realised I needed to view them
with an editor with fixed font width so everything lined up!

Just one query (its been years since I've done any of this stuff & I'm
pretty rusty), what do I do with the ground output from the cd player?
Connect it to the circuit GND, or just leave it floating?

Thanks once more,

Gavin.
 
J

John Fields

Jan 1, 1970
0
John, Ed,

Thanks both for your help with this; I'm off to try it out. Couldn't make
head or tail of the circuits for a start, realised I needed to view them
with an editor with fixed font width so everything lined up!

Just one query (its been years since I've done any of this stuff & I'm
pretty rusty), what do I do with the ground output from the cd player?
Connect it to the circuit GND, or just leave it floating?
 
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