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Thread

Re: [motm] Power Supply and Joystick advice

2000-04-12 by jwbarlow@aol.com

In a message dated 4/12/2000 9:44:23 AM, djthomaswhite@... writes:

>On the joystick level, I am looking for the best way to drop the +15/-15v
>volts from the 900 PSU to +10/-10v or +5/-5v for joystick use. Which voltage
>do you guys recommend?

Doesn't the Klein schematic show something about a lower voltage (like 10V 
maybe)? I say split the difference with a voltage divider (didn't I put 
something about this in there too)? Take one 100K resistor and put one side 
at 15V and on the other side place 1) a second 100K resistor, and 2) an 
OUTPUT. Connect the other side of the second 100K resistor to ground. The 
OUTPUT should be about 7.5V. I know I put some stuff about scaling and 
offsets in there, take a look at that too.

I hope someone smarter than me will chime in and correct any errors I may be 
spreading -- but it should be OK for a FracRack!
JB

Re: [motm] Power Supply and Joystick advice

2000-04-12 by thomas white

Thanks JB,

I just want to get a rounded opinion on the max voltage I should use. I am 
pretty new to figuring out resistance since I come from a purely "A into B" 
kit background (Duh). So what values in the voltage divider would I need to 
scale down to 10v? Thanks,

Thomas White

>From: jwbarlow@...
>Reply-To: motm@egroups.com
>To: motm@egroups.com
>Subject: Re: [motm] Power Supply and Joystick advice
>Date: Wed, 12 Apr 2000 14:33:02 EDT
>
>
>In a message dated 4/12/2000 9:44:23 AM, djthomaswhite@... writes:
>
> >On the joystick level, I am looking for the best way to drop the +15/-15v
> >volts from the 900 PSU to +10/-10v or +5/-5v for joystick use. Which 
>voltage
> >do you guys recommend?
>
>Doesn't the Klein schematic show something about a lower voltage (like 10V
>maybe)? I say split the difference with a voltage divider (didn't I put
>something about this in there too)? Take one 100K resistor and put one side
>at 15V and on the other side place 1) a second 100K resistor, and 2) an
>OUTPUT. Connect the other side of the second 100K resistor to ground. The
>OUTPUT should be about 7.5V. I know I put some stuff about scaling and
>offsets in there, take a look at that too.
>
>I hope someone smarter than me will chime in and correct any errors I may 
>be
>spreading -- but it should be OK for a FracRack!
>JB

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RE: [motm] Power Supply and Joystick advice

2000-04-12 by Dave Bradley

There are a zillion resistor value pairs that you could use. The important
factor to get a specific voltage is the ratio between the two resistors.
Blah blah insert a bunch of irrelevant theory here....

Bottom line:

Connect a 10K resistor to ground, and a 5.1K resistor to +15V of your MOTM
supply. Connect the free ends of the 2 resistors together, you'll get about
10V there. That's without trying to drive much of a load. To make the
circuit stable, connect the resistor junction to a voltage follower, which
is just any old opamp's positive input, with the negative input connected
directly to the output. Then the output of the opamp connects to one
joystick pot leg, the other pot leg goes to ground, and the pot wiper is the
joystick output.

Dave Bradley
Principal Software Engineer
Engineering Animation, Inc.
daveb@...

Show quoted textHide quoted text

> -----Original Message-----
> From: thomas white [mailto:djthomaswhite@...]
> Sent: Wednesday, April 12, 2000 1:50 PM
> To: motm@egroups.com
> Subject: Re: [motm] Power Supply and Joystick advice
>
>
> Thanks JB,
>
> I just want to get a rounded opinion on the max voltage I should
> use. I am
> pretty new to figuring out resistance since I come from a purely
> "A into B"
> kit background (Duh). So what values in the voltage divider would
> I need to
> scale down to 10v? Thanks,
>
> Thomas White
>
> >From: jwbarlow@...
> >Reply-To: motm@egroups.com
> >To: motm@egroups.com
> >Subject: Re: [motm] Power Supply and Joystick advice
> >Date: Wed, 12 Apr 2000 14:33:02 EDT
> >
> >
> >In a message dated 4/12/2000 9:44:23 AM,
> djthomaswhite@... writes:
> >
> > >On the joystick level, I am looking for the best way to drop
> the +15/-15v
> > >volts from the 900 PSU to +10/-10v or +5/-5v for joystick use. Which
> >voltage
> > >do you guys recommend?
> >
> >Doesn't the Klein schematic show something about a lower voltage
> (like 10V
> >maybe)? I say split the difference with a voltage divider (didn't I put
> >something about this in there too)? Take one 100K resistor and
> put one side
> >at 15V and on the other side place 1) a second 100K resistor, and 2) an
> >OUTPUT. Connect the other side of the second 100K resistor to ground. The
> >OUTPUT should be about 7.5V. I know I put some stuff about scaling and
> >offsets in there, take a look at that too.
> >
> >I hope someone smarter than me will chime in and correct any
> errors I may
> >be
> >spreading -- but it should be OK for a FracRack!
> >JB
>
> ______________________________________________________
> Get Your Private, Free Email at http://www.hotmail.com
>
>
> ------------------------------------------------------------------------
> Motown & Soul Fanatics: Baby we need your ratings!
> New Music Site seeks song raters with a fine ear.
> Share what you know, and get compensated too.  JABOOM
> http://click.egroups.com/1/3346/3/_/529958/_/955565397/
> ------------------------------------------------------------------------
>
>

Re: [motm] Power Supply and Joystick advice

2000-04-12 by jwbarlow@aol.com

In a message dated 4/12/2000 11:50:51 AM, djthomaswhite@... writes:

>So what values in the voltage divider would I need to 
>scale down to 10v?

It might be worth it to get a basic electronics book (like those ones they 
have at Radio Shack, if not a better one).

Here's the general formula for a voltage divider:

Vout = Vin (R2/(R1 + R2))

where R2 is the resistor connected to ground on one side, and R1 is connected 
to positive on one side.

Specifically:

10 = 15 (R2/(R1 + R2))
divide both sides by 15

2/3 = R2/(R1 + R2)

so, if you choose R2 to be 100K then R1 would be 50K -- I'd want to stay in 
this (100K) range unless someone smart speaks up. There are other ways to 
accomplish this, but I wouldn't use successive diode drops (like 0.6V each) 
or a regulator (zener or otherwise) -- too much hassle. Especially since R2 
might be a pot you already have as an attenuator, and you could just hang R1 
off the back of that same pot PAiA style.

JB

RE: [motm] Power Supply and Joystick advice

2000-04-12 by Dave Bradley

Never mind my last post. The output would only swing from +10 to 0 volts,
and bipolar would probably be more useful. See the attached image for a
quick and easy schematic. The opamp type is not critical.

Dave Bradley
Principal Software Engineer
Engineering Animation, Inc.
daveb@...

Show quoted textHide quoted text

> -----Original Message-----
> From: Dave Bradley [mailto:daveb@...]
> Sent: Wednesday, April 12, 2000 3:27 PM
> To: motm@egroups.com
> Subject: RE: [motm] Power Supply and Joystick advice
>
>
> There are a zillion resistor value pairs that you could use. The important
> factor to get a specific voltage is the ratio between the two resistors.
> Blah blah insert a bunch of irrelevant theory here....
>
> Bottom line:
>
> Connect a 10K resistor to ground, and a 5.1K resistor to +15V of your MOTM
> supply. Connect the free ends of the 2 resistors together, you'll
> get about
> 10V there. That's without trying to drive much of a load. To make the
> circuit stable, connect the resistor junction to a voltage follower, which
> is just any old opamp's positive input, with the negative input connected
> directly to the output. Then the output of the opamp connects to one
> joystick pot leg, the other pot leg goes to ground, and the pot
> wiper is the
> joystick output.
>
> Dave Bradley
> Principal Software Engineer
> Engineering Animation, Inc.
> daveb@...
>
> > -----Original Message-----
> > From: thomas white [mailto:djthomaswhite@...]
> > Sent: Wednesday, April 12, 2000 1:50 PM
> > To: motm@egroups.com
> > Subject: Re: [motm] Power Supply and Joystick advice
> >
> >
> > Thanks JB,
> >
> > I just want to get a rounded opinion on the max voltage I should
> > use. I am
> > pretty new to figuring out resistance since I come from a purely
> > "A into B"
> > kit background (Duh). So what values in the voltage divider would
> > I need to
> > scale down to 10v? Thanks,
> >
> > Thomas White
> >
> > >From: jwbarlow@...
> > >Reply-To: motm@egroups.com
> > >To: motm@egroups.com
> > >Subject: Re: [motm] Power Supply and Joystick advice
> > >Date: Wed, 12 Apr 2000 14:33:02 EDT
> > >
> > >
> > >In a message dated 4/12/2000 9:44:23 AM,
> > djthomaswhite@... writes:
> > >
> > > >On the joystick level, I am looking for the best way to drop
> > the +15/-15v
> > > >volts from the 900 PSU to +10/-10v or +5/-5v for joystick use. Which
> > >voltage
> > > >do you guys recommend?
> > >
> > >Doesn't the Klein schematic show something about a lower voltage
> > (like 10V
> > >maybe)? I say split the difference with a voltage divider (didn't I put
> > >something about this in there too)? Take one 100K resistor and
> > put one side
> > >at 15V and on the other side place 1) a second 100K resistor, and 2) an
> > >OUTPUT. Connect the other side of the second 100K resistor to
> ground. The
> > >OUTPUT should be about 7.5V. I know I put some stuff about scaling and
> > >offsets in there, take a look at that too.
> > >
> > >I hope someone smarter than me will chime in and correct any
> > errors I may
> > >be
> > >spreading -- but it should be OK for a FracRack!
> > >JB
> >
> > ______________________________________________________
> > Get Your Private, Free Email at http://www.hotmail.com
> >
> >
> > ------------------------------------------------------------------------
> > Motown & Soul Fanatics: Baby we need your ratings!
> > New Music Site seeks song raters with a fine ear.
> > Share what you know, and get compensated too.  JABOOM
> > http://click.egroups.com/1/3346/3/_/529958/_/955565397/
> > ------------------------------------------------------------------------
> >
> >
>
>
> ------------------------------------------------------------------------
> 1.6 Million Digital Images!
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> http://click.egroups.com/1/3356/3/_/529958/_/955571368/
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>
>

RE: [motm] Power Supply and Joystick advice

2000-04-12 by thomas white

Hello Ken,

I have schematics for this in a radio shack circuit book. This is a good 
method, but the end result is easier with JB's way of division I think. 
Thanks

Thomas White


>From: "Tkacs, Ken" <ken.tkacs@...>
>Reply-To: motm@egroups.com
>To: "'motm@egroups.com'" <motm@egroups.com>
>Subject: RE: [motm] Power Supply and Joystick advice
>Date: Wed, 12 Apr 2000 14:48:57 -0400
>
>
>I'm no engineer...
>
>Can't you use diodes as a voltage divider to get your 15v down to whatever
>you need it to be? I seem to remember reading that you take a bunch of
>diodes with particular breakdown values... put them in series until you get
>the drop you're looking for.
>
>
>
>

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