converting line level audio to resistance?

[Mad Scientist Jr]

Are you trying to make something like an oscilloscope, to display something

like a Lissajous pattern (ever-changing squiggly thing that shows phase and
frequency relationship between two channels)? Or are you trying to make
something that just moves the paddles depending on how loud the sound is?
If the former, you're probably out of luck; I don't think the Atari itself
will respond to paddle movement at 20kHz.

The latter would be easier and would probably do the job, but the
oscilloscope version would probably be more interesting. If the circuit
could take the frequency (say 0 Hz - 20,000 Hz) and find the equivalent
fraction within the Atari's range (1k ohm thru 1 MOhm), then it would
be able to convert it to paddle movement the Atari will recognize.

 

[John Woodgate]

I read in sci.electronics.design that Mad Scientist Jr

1) blowing up the stereo if the output resistance is not 8 ohms (or
whatever the output expects for headphones) - that's why I originally
said Line Level, this would be a single standard as opposed to
different stereos which need different resistance speakers.

You are trying to do something beyond your present understanding, so you
need to learn. You do that by reading the advice you are given
carefully.

You will not blow up the stereo if you feed its output into anything
LARGER than 8 ohms. It doesn't need 8 ohms across the output (unless you
have some weird audiophool amplifier). The loudspeaker or headphone
output will give you 5 V of audio, but the line level output will not;
you might get a maximum of 2 V but probably less.

However, you should include a diode (1N4148, anode to the stereo) in
series between the stereo hot output and the **slider** connection of
the paddle, which must be disconnected from the actual slider. The input
might well not like -5V at all. You do not connect anything to the +5 V
at the 'top' end of the paddle resistance, so it doesn't come into the
scene at all. The 'cold' output from the stereo goes to the ground end
of the paddle resistance.

2) blowing up the video game - it sends 5v out and measures how much of
that comes back. I assume the signal from the stereo sends voltage as
well. So what happens when you have the 5V from the game, plus the
volts from the stereo?

See above. The 5 V is no longer connected to the connection that went to
the slider.

What if the game can only handle at most the 5v it is sending out?
Therefore, I would rather make a circuit that 1) controls resistance

This is not only impossible in the way you want it, it isn't the right
way to do it.

2) provides some attenuation so the stereo doesn't blow up

That doesn't make any sort of sense. Don't just throw out technical
words, try to learn. If you don't want to learn, please go away.

 

[Don Bowey]

That sounds easy, I will need to multimeter it.

2 dangers:

1) blowing up the stereo if the output resistance is not 8 ohms (or
whatever the output expects for headphones) - that's why I originally
said Line Level, this would be a single standard as opposed to
different stereos which need different resistance speakers.

2) blowing up the video game - it sends 5v out and measures how much of
that comes back. I assume the signal from the stereo sends voltage as
well. So what happens when you have the 5V from the game, plus the
volts from the stereo? What if the game can only handle at most the 5v
it is sending out? Therefore, I would rather make a circuit that 1)
controls resistance 2) provides some attenuation so the stereo doesn't
blow up


on with your life...

The way your pots are connected suggests that your game is already
voltage
driven, so you would only have to amplify your audio to cover the 0-5V
range. For starters try connecting your audio output directly to the
paddle
pin (and gnd to gnd) and see what happens.


Foo,D

If you are going to connect the line level voltage to replace the paddle ,
then you will not use the 5V connection. The voltage reference will be the
audio ground. Just in case it hasn't been mentioned, it would be a good
idea to put a diode in the circuit path to assure that only a positive
voltage is applied. You can protect the input further, by putting a 250k or
1 Meg resistor in series with the audio - Atari connection. For protection,
start with the high R and reduce to a lower value if more current is needed.

Don

 

[Rich Grise]

It's not entirely clear to me why a responder would want or need
to cut and paste, but with modern software it's arguably easier
than having to dig for a post that mysteriously disappeared because
you marked it "read" in some other newsgroup. Which is why some
folks prefer multiposting to crossposting.

But if it's marked "read", doesn't that mean that you've already
read it? Why do you want to read the same post five different times
in five different places? Maybe the third or fourth time you read
the same old thing over and over again, you'll have thought of
an answer?

Then shouldn't the people in the other NGs benefit from your answer
too?

Crosspost.

Cheers!
Rich

 

[Rich Grise]

I think we should just ignore googlegroupies as a matter of policy.

Thanks,
Rich

 

[Rich Grise]

Now that's a cool idea. Let your stereo do the playing for you while you get
on with your life...

The way your pots are connected suggests that your game is already voltage
driven, so you would only have to amplify your audio to cover the 0-5V
range. For starters try connecting your audio output directly to the paddle
pin (and gnd to gnd) and see what happens.

Do you have a schematic? In the IBM joystick input, the pots are
wired as rheostats and go to +5 on one end and are the timing
resistors for one-shots - i.e., their other end just goes to
the timing cap - a DC voltage won't work and could damage your
game port.

It's not clear at all from that little chart what's really going on
inside the atari thing.

And what would it do anyway? Louder goes to the right, softer to
the left? ??:-|

Thanks,
Rich

 

[Mad Scientist Jr]

That doesn't make any sort of sense. Don't just throw out technical

words, try to learn.

Fair enough, I have to digest all this and I have some reading to do.

Thanks to you and everyone for your replies.



18. John Woodgate Sep 20, 12:00 pm show options

 

[John Woodgate]

I read in sci.electronics.design that Rich Grise <[email protected]>

In the IBM joystick input, the pots are wired as rheostats and go to +5
on one end and are the timing resistors for one-shots - i.e., their
other end just goes to the timing cap - a DC voltage won't work and
could damage your game port.

Would you just take a minute to think about that? What comes out of the
slider? a timing resistance or a voltage between 0 and 5 V? If it were a
timing resistance, it wouldn't need the 5 V supply.

 

[John Fields]

snip
even tougher than that is
having to cut and paste and repost or retype and repost earlier
replies because a querying poster (you) didn't crosspost to all the
groups where the question was presented.

It's not entirely clear to me why a responder would want or need
to cut and paste, but with modern software it's arguably easier
than having to dig for a post that mysteriously disappeared because
you marked it "read" in some other newsgroup. Which is why some
folks prefer multiposting to crossposting.

---
You seem to have missed the point, which is that If I respond to a
post in, say, seb and then, later, find that identical post in sed
(but not crossposted) I will either have to not respond, go back to
seb, locate and copy my earlier response, then go to sed, find the
OP's post, paste my response into it and, finally, send it, or
retype a separate response.

As far as software goes, I think it's relatively easy to set up a
newsreader so it marks posts read but doesn't kill them. At least I
don't have that problem, and I'm using Agent.

 

[Mad Scientist Jr]

I basically want to control a video game (Atari 2600 paddle controls
are 1 MOhm pots connected to 5V DC) with my stereo.

See "paddles"
http://www.hardwarebook.net/connector/userinput/atari2600joy.html

I don't think it has to be zero ohms exactly but a low amount.

Thanks

 

[Mad Scientist Jr]

That's an interesting idea - how would you get the circuit to max out
at 1 MOhm and at a minimum, go to as close to 0 ohms as possible?

 

[Deefoo]

I basically want to control a video game (Atari 2600 paddle controls
are 1 MOhm pots connected to 5V DC) with my stereo.

Now that's a cool idea. Let your stereo do the playing for you while
you get
on with your life...

The way your pots are connected suggests that your game is already
voltage
driven, so you would only have to amplify your audio to cover the 0-5V
range. For starters try connecting your audio output directly to the
paddle
pin (and gnd to gnd) and see what happens.

Foo,D

 

[Mad Scientist Jr]

I'll just end this subtopic and say I was a dumbass and multiposted by
mistake - I posted and then had a 2nd thought "maybe it would be
better
in .design instead of .misc" and posted there too. Sorry for the
inconvenience.

 

[Frank Bemelman]

"Pooh Bear" <[email protected]> schreef in
bericht

Mad Scientist Jr wrote:

I need to take a line level audio signal and convert it to resistance
in the range between 0 Ohm and 1 MOhm. Is this difficult to do for a
beginner in electronics?

V = I*R

therefore R = V / I

So all you have to do is divide the voltage by the current.

Very good, very good indeed

I was about to suggest a fixed 470K resistor and forget about the
audio signal.

 

[Walter Harley]

I basically want to control a video game (Atari 2600 paddle controls
are 1 MOhm pots connected to 5V DC) with my stereo.

See "paddles"
http://www.hardwarebook.net/connector/userinput/atari2600joy.html

I don't think it has to be zero ohms exactly but a low amount.

I'm not clear whether you want the resistance to be related to the
envelope
(average volume) of the signal, or to the instantaneous voltage.

Are you trying to make something like an oscilloscope, to display
something
like a Lissajous pattern (ever-changing squiggly thing that shows
phase and
frequency relationship between two channels)? Or are you trying to
make
something that just moves the paddles depending on how loud the sound
is?

If the former, you're probably out of luck; I don't think the Atari
itself
will respond to paddle movement at 20kHz.

If the latter, then Rene's light bulb idea is not a bad one. One
problem is
that light-dependent resistors (LDRs) with 1MEG dark resistance are
usually
pretty slow, taking as much as several seconds of darkness to get all
the
way to 1MEG. The resistance will go low in a hurry, but it takes a
long
time to recover to high - it's sort of like your eyes when they
dark-adapt.

Either way, you probably only need a current or a voltage, not a
resistance.
That's considerably easier. And I wouldn't worry about getting the
(effective) resistance any lower than 1k ohms, since the pots in the
joystick are almost certainly linear (as opposed to log-taper): the
difference between 1k and 0 is 0.1% which is less than the pots
themselves
can distinguish.

Give Rene's idea a try, as a start. If it doesn't work you can evolve
it.

 

[John Fields]

That's an interesting idea - how would you get the circuit to max out
at 1 MOhm and at a minimum, go to as close to 0 ohms as possible?

 

[Mad Scientist Jr]

Maybe it's this damn google groups interface, you click Reply and
assume it is quoting the original article and then it doesn't

If you'd leave enough of the post you're replying to in your post to
let us know what you're responding to then we won't have to digging

for it.

 

[Mad Scientist Jr]

That sounds easy, I will need to multimeter it

2 dangers

1) blowing up the stereo if the output resistance is not 8 ohms (o
whatever the output expects for headphones) - that's why I originall
said Line Level, this would be a single standard as opposed t
different stereos which need different resistance speakers

2) blowing up the video game - it sends 5v out and measures how muc
o
that comes back. I assume the signal from the stereo sends voltage a
well. So what happens when you have the 5V from the game, plus th
volts from the stereo? What if the game can only handle at most the 5
it is sending out? Therefore, I would rather make a circuit that 1
controls resistance 2) provides some attenuation so the stereo doesn'
blow u

I basically want to control a video game (Atari 2600 paddle control
are 1 MOhm pots connected to 5V DC) with my stereo

Now that's a cool idea. Let your stereo do the playing for you whil you ge
on with your life..

The way your pots are connected suggests that your game is alread
voltag
driven, so you would only have to amplify your audio to cover the 0-5
range. For starters try connecting your audio output directly to th
paddle
pin (and gnd to gnd) and see what happens.

Foo,

 

[Mad Scientist Jr]

Are you trying to make something like an oscilloscope, to display
something

like a Lissajous pattern (ever-changing squiggly thing that shows phase and
frequency relationship between two channels)? Or are you trying to make
something that just moves the paddles depending on how loud the sound is?
If the former, you're probably out of luck; I don't think the Atari itself
will respond to paddle movement at 20kHz.

The latter would be easier and would probably do the job, but the
oscilloscope version would probably be more interesting. If the
circuit
could take the frequency (say 0 Hz - 20,000 Hz) and find the
equivalent
fraction within the Atari's range (1k ohm thru 1 MOhm), then it would
be able to convert it to paddle movement the Atari will recognize.

 

[John Woodgate]

I read in sci.electronics.design that Mad Scientist Jr

1) blowing up the stereo if the output resistance is not 8 ohms (or
whatever the output expects for headphones) - that's why I originally
said Line Level, this would be a single standard as opposed to
different stereos which need different resistance speakers.

You are trying to do something beyond your present understanding, so
you
need to learn. You do that by reading the advice you are given
carefully.

You will not blow up the stereo if you feed its output into anything
LARGER than 8 ohms. It doesn't need 8 ohms across the output (unless
you
have some weird audiophool amplifier). The loudspeaker or headphone
output will give you 5 V of audio, but the line level output will not;

you might get a maximum of 2 V but probably less.

However, you should include a diode (1N4148, anode to the stereo) in
series between the stereo hot output and the **slider** connection of
the paddle, which must be disconnected from the actual slider. The
input
might well not like -5V at all. You do not connect anything to the +5
V
at the 'top' end of the paddle resistance, so it doesn't come into the

scene at all. The 'cold' output from the stereo goes to the ground end

of the paddle resistance.

2) blowing up the video game - it sends 5v out and measures how much of
that comes back. I assume the signal from the stereo sends voltage as
well. So what happens when you have the 5V from the game, plus the
volts from the stereo?

See above. The 5 V is no longer connected to the connection that went
to
the slider.

What if the game can only handle at most the 5v it is sending out?
Therefore, I would rather make a circuit that 1) controls resistance

This is not only impossible in the way you want it, it isn't the right

way to do it.

2) provides some attenuation so the stereo doesn't blow up

That doesn't make any sort of sense. Don't just throw out technical
words, try to learn. If you don't want to learn, please go away.