Question about all electronic auto instrument

I've got a junked Ford auto instrument panel. It has 6 actuators for
the tach, speed, fuel, etc. Identical 1" X 1-1/8" X 1/2" white
plastic modules with four wires. Inside is a little (for lack of a
better word) geared down stepper motor.

It might be a bipolar stepper except the two identical 170 ohm coils
have a common third pole (in the magnetic circuit). The coils are set
in a 90 degree "V" configuration. Three double gears to turn the
(1/16" X 1/2") output shaft.

It is very easy to take apart and reassemble. .

The rotor appears to be a permanent magnet type with at least four
(probably more like 8) poles. Rotation is limited to 270 degrees with
a mechanical stop on the output shaft's gear.

Anyone know how they work and what it takes to drive one?

 

[Tim Wescott]

On Mon, 01 Aug 2011 08:20:19 -0400, default wrote:

I've got a junked Ford auto instrument panel. It has 6 actuators for
the tach, speed, fuel, etc. Identical 1" X 1-1/8" X 1/2" white plastic
modules with four wires. Inside is a little (for lack of a better word)
geared down stepper motor.

It might be a bipolar stepper except the two identical 170 ohm coils
have a common third pole (in the magnetic circuit). The coils are set
in a 90 degree "V" configuration. Three double gears to turn the (1/16"
X 1/2") output shaft.

It is very easy to take apart and reassemble. .

The rotor appears to be a permanent magnet type with at least four
(probably more like 8) poles. Rotation is limited to 270 degrees with a
mechanical stop on the output shaft's gear.

Anyone know how they work and what it takes to drive one?

I have an acquaintance who used to work for a company that makes
instruments like that for trucks. They work like stepper motors. I'd
play around with a power supply and see if you can figure out what makes
the motor step.

I expect that the motor is very wimpy (it doesn't need to be strong,
because it's just moving a needle, after all) and that there's no
position feedback -- when the controlling microprocessor comes out of
reset it just drives the thing into the pin for 270 degrees worth of
steps, then it just counts steps after that.



--
www.wescottdesign.com

 

On Mon, 01 Aug 2011 13:06:20 -0500, Tim Wescott <tim@seemywebsite.com>
wrote:

On Mon, 01 Aug 2011 08:20:19 -0400, default wrote:

I've got a junked Ford auto instrument panel. It has 6 actuators for
the tach, speed, fuel, etc. Identical 1" X 1-1/8" X 1/2" white plastic
modules with four wires. Inside is a little (for lack of a better word)
geared down stepper motor.

It might be a bipolar stepper except the two identical 170 ohm coils
have a common third pole (in the magnetic circuit). The coils are set
in a 90 degree "V" configuration. Three double gears to turn the (1/16"
X 1/2") output shaft.

It is very easy to take apart and reassemble. .

The rotor appears to be a permanent magnet type with at least four
(probably more like 8) poles. Rotation is limited to 270 degrees with a
mechanical stop on the output shaft's gear.

Anyone know how they work and what it takes to drive one?

I have an acquaintance who used to work for a company that makes
instruments like that for trucks. They work like stepper motors. I'd
play around with a power supply and see if you can figure out what makes
the motor step.

I expect that the motor is very wimpy (it doesn't need to be strong,
because it's just moving a needle, after all) and that there's no
position feedback -- when the controlling microprocessor comes out of
reset it just drives the thing into the pin for 270 degrees worth of
steps, then it just counts steps after that.

The more I look at it, the more it looks like a stepper. The unusual
pole arrangement may just be to accommodate the coils in a small
package.

No telling with what passes for electronics in Detroit...

 

[Bob Masta]

On Mon, 01 Aug 2011 13:06:20 -0500, Tim Wescott
<tim@seemywebsite.com> wrote:

On Mon, 01 Aug 2011 08:20:19 -0400, default wrote:

I've got a junked Ford auto instrument panel. It has 6 actuators for
the tach, speed, fuel, etc. Identical 1" X 1-1/8" X 1/2" white plastic
modules with four wires. Inside is a little (for lack of a better word)
geared down stepper motor.

It might be a bipolar stepper except the two identical 170 ohm coils
have a common third pole (in the magnetic circuit). The coils are set
in a 90 degree "V" configuration. Three double gears to turn the (1/16"
X 1/2") output shaft.

It is very easy to take apart and reassemble. .

The rotor appears to be a permanent magnet type with at least four
(probably more like 8) poles. Rotation is limited to 270 degrees with a
mechanical stop on the output shaft's gear.

Anyone know how they work and what it takes to drive one?

I have an acquaintance who used to work for a company that makes
instruments like that for trucks. They work like stepper motors. I'd
play around with a power supply and see if you can figure out what makes
the motor step.

I expect that the motor is very wimpy (it doesn't need to be strong,
because it's just moving a needle, after all) and that there's no
position feedback -- when the controlling microprocessor comes out of
reset it just drives the thing into the pin for 270 degrees worth of
steps, then it just counts steps after that.

I wonder if these things could be "selsyns", also known as
"synchos"? Essentially, they are like steppers that get
their drive pulses from a matching unit at the sensor. (As
I recall, you can cross-wire certain conventional steppers
to behave this way.) But the original selsyns were around
long before steppers, used in aircraft and industrial
instrumentation for example.

Best regards,


Bob Masta

DAQARTA v6.02
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, FREE Signal Generator
Pitch Track, Pitch-to-MIDI
Science with your sound card!

 

On Tue, 02 Aug 2011 11:54:02 GMT, N0Spam@daqarta.com (Bob Masta)
wrote:

On Mon, 01 Aug 2011 13:06:20 -0500, Tim Wescott
tim@seemywebsite.com> wrote:

On Mon, 01 Aug 2011 08:20:19 -0400, default wrote:

I've got a junked Ford auto instrument panel. It has 6 actuators for
the tach, speed, fuel, etc. Identical 1" X 1-1/8" X 1/2" white plastic
modules with four wires. Inside is a little (for lack of a better word)
geared down stepper motor.

It might be a bipolar stepper except the two identical 170 ohm coils
have a common third pole (in the magnetic circuit). The coils are set
in a 90 degree "V" configuration. Three double gears to turn the (1/16"
X 1/2") output shaft.

It is very easy to take apart and reassemble. .

The rotor appears to be a permanent magnet type with at least four
(probably more like 8) poles. Rotation is limited to 270 degrees with a
mechanical stop on the output shaft's gear.

Anyone know how they work and what it takes to drive one?

I have an acquaintance who used to work for a company that makes
instruments like that for trucks. They work like stepper motors. I'd
play around with a power supply and see if you can figure out what makes
the motor step.

I expect that the motor is very wimpy (it doesn't need to be strong,
because it's just moving a needle, after all) and that there's no
position feedback -- when the controlling microprocessor comes out of
reset it just drives the thing into the pin for 270 degrees worth of
steps, then it just counts steps after that.

I wonder if these things could be "selsyns", also known as
"synchos"? Essentially, they are like steppers that get
their drive pulses from a matching unit at the sensor. (As
I recall, you can cross-wire certain conventional steppers
to behave this way.) But the original selsyns were around
long before steppers, used in aircraft and industrial
instrumentation for example.

Best regards,


Bob Masta

Selsyns are rotary transformers - the rotor is excited via slip rings

and the stator is usually a three phase transformer (or motor). The
phase of the rotor versus the field/stator determines position - 5 or
6 wires.

 

[Jasen Betts]

On 2011-08-02, Bob Masta <N0Spam@daqarta.com> wrote:

I wonder if these things could be "selsyns", also known as
"synchos"? Essentially, they are like steppers that get
their drive pulses from a matching unit at the sensor. (As
I recall, you can cross-wire certain conventional steppers
to behave this way.) But the original selsyns were around
long before steppers, used in aircraft and industrial
instrumentation for example.

Selsyns (self-syncronous servos) use an alternating field,

You can wire permanent magnet steppers together like selsyns,
if you turn the master fast enough to generate voltage to
turn the slave the slave will follow it, but at slow speed it won't
follow.

selsyns work at any speed because the master acts as a variable
transformer thus there's always voltage on the signal wires.
the slave moves to match the master minimising the current flowing in
the signal wires.

--
⚂⚃ 100% natural

 

[Roberto Waltman]

default wrote:

I've got a junked Ford auto instrument panel. It has 6 actuators for
the tach, speed, fuel, etc. Identical 1" X 1-1/8" X 1/2" white
plastic modules with four wires. Inside is a little (for lack of a
better word) geared down stepper motor.
...
Anyone know how they work and what it takes to drive one?

Swisstech products are very common - Check:
http://jukenswisstech.com/index.php/products/x27/
http://jukenswisstech.com/index.php/products/quad-driver/
http://jukenswisstech.com/index.php/documentation/
http://jukenswisstech.com/index.php/products/
--
Roberto Waltman

[ Please reply to the group.
Return address is invalid ]

 

[tuinkabouter]

On 8/4/2011 8:58 PM, Roberto Waltman wrote:

Roberto Waltman

[ Please reply to the group.
Return address is invalid ]

Is domain waltman.com from you?
No? then don't use that domain for your return address.
Use waltman.invalid instead.

 

[Roberto Waltman]

tuinkabouter wrote:

Is domain waltman.com from you?

Yes it is. - The "invalid" in my signature means that although the
email address exists, I gave it a zero quota, so any message sent
there will be rejected.
--
Roberto Waltman

[ Please reply to the group.
Return address is invalid ]

 

On 4 Aug 2011 13:30:18 GMT, Jasen Betts <jasen@xnet.co.nz> wrote:

On 2011-08-02, Bob Masta <N0Spam@daqarta.com> wrote:


I wonder if these things could be "selsyns", also known as
"synchos"? Essentially, they are like steppers that get
their drive pulses from a matching unit at the sensor. (As
I recall, you can cross-wire certain conventional steppers
to behave this way.) But the original selsyns were around
long before steppers, used in aircraft and industrial
instrumentation for example.

Selsyns (self-syncronous servos) use an alternating field,

You can wire permanent magnet steppers together like selsyns,
if you turn the master fast enough to generate voltage to
turn the slave the slave will follow it, but at slow speed it won't
follow.

selsyns work at any speed because the master acts as a variable
transformer thus there's always voltage on the signal wires.
the slave moves to match the master minimising the current flowing in
the signal wires.

I fooled around with that - never could get any results with one
stepper driving another directly, but did get reasonable results by
adding some Darlington transistors - but still had to have enough
speed to bias the Darlington on.

Adding op amps made a pretty good system. Open loop gain of 200K
driving a Darlington with 1K gain. I couldn't turn the generator
stepper so slow that the motor stepper wouldn't also turn. Downside
was there was no holding torque except for any friction in the
mechanical load or cogging in the motor stepper - doubtless some flip
flops could be added to provide power to the motor coils when the
generator was still - but I never carried it that far.

I used it for a remotely located antenna tuner.

 

On Thu, 04 Aug 2011 14:58:18 -0400, Roberto Waltman
<usenet@rwaltman.com> wrote:

default wrote:
I've got a junked Ford auto instrument panel. It has 6 actuators for
the tach, speed, fuel, etc. Identical 1" X 1-1/8" X 1/2" white
plastic modules with four wires. Inside is a little (for lack of a
better word) geared down stepper motor.
...
Anyone know how they work and what it takes to drive one?

Swisstech products are very common - Check:
http://jukenswisstech.com/index.php/products/x27/
http://jukenswisstech.com/index.php/products/quad-driver/
http://jukenswisstech.com/index.php/documentation/
http://jukenswisstech.com/index.php/products/

Thanks. Not the exact model I have but it looks like the same general
idea - even including the snap apart case.

 

[Roberto Waltman]

default wrote:

Roberto Waltman wrote:
Swisstech products are very common - Check:
http://jukenswisstech.com/index.php/products/x27/

Thanks. Not the exact model I have but it looks like the same general
idea - even including the snap apart case.

I never used them, (except, unknowingly, in my car,) but I was looking
to buy a few for a home-built flight simulator instrument panel.
You may have older models - I remember different part numbers, they
may have revamped the product line when bought by Juken.
Also the documentation used to be free. Now some PDFs are marked
"restricted" and require you to sign up to download them.
There are many in eBay if you want to experiment without dissasembling
what you have:

http://cgi.ebay.com/ebaymotors/6-03-04-05-CHEVY-TAHOE-X25-168-CLUSTER-STEPPER-MOTORS-_W0QQcmdZViewItemQQhashZitem4837412eddQQitemZ310164664029QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories
http://cgi.ebay.com/ebaymotors/1-03-04-05-06-SIERRA-SPEEDO-CLUSTER-GM-STEPPER-MOTOR-_W0QQcmdZViewItemQQhashZitem3a602d43dbQQitemZ250721682395QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

--
Roberto Waltman

[ Please reply to the group.
Return address is invalid ]

 

[Roberto Waltman]

Roberto Waltman wrote:

... I was looking
to buy a few for a home-built flight simulator instrument panel.

Like those. (1st clip: The green PCB in the center has the 4-channel
driver chip controlling the others.)

http://www.youtube.com/watch?v=ihD5KjVnOEA
http://www.youtube.com/watch?v=6byE-UdVRxA
http://www.youtube.com/watch?v=jY0H0eip0Sw

--
Roberto Waltman

[ Please reply to the group.
Return address is invalid ]

 

[Jasen Betts]

On 2011-08-03, default <default> wrote:

Selsyns are rotary transformers - the rotor is excited via slip rings
and the stator is usually a three phase transformer (or motor). The
phase of the rotor versus the field/stator determines position - 5 or
6 wires.

4 wires will work. two for the rotor and one of the three for the
stator can share one of the rotor wires as there's no other current
path between the stator and the rotor.

R1
R2
R3 + S1
S2

but 5 wires will work better if the wiring has significant resistance.

--
⚂⚃ 100% natural

 

[BobG]

On Aug 1, 8:20 am, default wrote:

I've got a junked Ford auto instrument panel.  It has 6 actuators for
the tach, speed, fuel, etc.  Identical 1" X 1-1/8" X 1/2" white
plastic modules with four wires.  Inside is a little (for lack of a
better word) geared down stepper motor.  

It might be a bipolar stepper except the two identical 170 ohm coils
have a common third pole (in the magnetic circuit).  The coils are set
in a 90 degree "V" configuration.  Three double gears to turn the
(1/16" X 1/2") output shaft.

 It is very easy to take apart and reassemble. .

The rotor appears to be a permanent magnet type with at least four
(probably more like 8) poles.  Rotation is limited to 270 degrees with
a mechanical stop on the output shaft's gear.

Anyone know how they work and what it takes to drive one?  

Search for 'aircore motor'. Put sin on one coil and cos on another
from a dac to drive it.

 

[default]

On Fri, 5 Aug 2011 09:26:40 -0700 (PDT), BobG <bobgardner@aol.com>
wrote:

On Aug 1, 8:20 am, default wrote:
I've got a junked Ford auto instrument panel.  It has 6 actuators for
the tach, speed, fuel, etc.  Identical 1" X 1-1/8" X 1/2" white
plastic modules with four wires.  Inside is a little (for lack of a
better word) geared down stepper motor.  

It might be a bipolar stepper except the two identical 170 ohm coils
have a common third pole (in the magnetic circuit).  The coils are set
in a 90 degree "V" configuration.  Three double gears to turn the
(1/16" X 1/2") output shaft.

 It is very easy to take apart and reassemble. .

The rotor appears to be a permanent magnet type with at least four
(probably more like 8) poles.  Rotation is limited to 270 degrees with
a mechanical stop on the output shaft's gear.

Anyone know how they work and what it takes to drive one?  

Search for 'aircore motor'. Put sin on one coil and cos on another
from a dac to drive it.

I ruled that out already - the 90 degree coil arrangement suggested it
and I remember a national IC designed just for the purpose. The
beauty of sin/cos is absolute position information - no need for
feedback to tell you where the pointer is. But the use of iron poles
and magnetic rotor means it "cogs" (favors some angles and wouldn't be
linear) then the >100:1 gear ratio would seem to render the absolute
position advantage moot.

This is Detroit electronics - they evolve their current systems and
adapt them to existing systems - so they aren't replacing their
current stock of parts. Adaptive engineering, versus design
engineering.

That is to say, it may not make a lot of sense, from an elegance of
design perspective.
--