[geoff]

Anybody know the power/current consumption of an ST-11. I have a USA
version coming and will need to build or source a 110v 60Hz
inverter/whatever supply to run it from 230v 50Hz.

Doesn't mention the power spec in the manual, though it does have
schematic and component list !

geoff

[Mike Rivers[_2_]]

On 5/20/2019 7:08 AM, geoff wrote:
Anybody know the power/current consumption of an ST-11

Like anyone else who doesn't have one and an ammeter, I don't know. But
I'll remind you that it's a synchronous motor that makes it work, so the
accuracy of the 60 Hz is of utmost importance if you actually intend to
tune with it and not just show it off to your buddies.

When you get it, hook up an oscillator (at 60 Hz, of course) to a power
amplifier, and connect the tuner to the amplifier output through a
backwards filament transformer. Bring up the gain slowly while
monitoring the voltage to the tuner, and when it reads 115 or 120 volts,
measure the current.

I have a friend who's into aircraft instruments, most of which run on
400 Hz AC. He's set up a similar osciallator-amplifier-transformer rig
to play with his toys.

[geoff]

On 20/05/2019 11:58 PM, Mike Rivers wrote:
On 5/20/2019 7:08 AM, geoff wrote:
Anybody know the power/current consumption of an ST-11

Like anyone else who doesn't have one and an ammeter, I don't know. But
I'll remind you that it's a synchronous motor that makes it work, so the
accuracy of the 60 Hz is of utmost importance if you actually intend to
tune with it and not just show it off to your buddies.

When you get it, hook up an oscillator (at 60 Hz, of course) to a power
amplifier, and connect the tuner to the amplifier output through a
backwards filament transformer. Bring up the gain slowly while
monitoring the voltage to the tuner, and when it reads 115 or 120 volts,
measure the current.

I have a friend who's into aircraft instruments, most of which run on
400 Hz AC. He's set up a similar osciallator-amplifier-transformer rig
to play with his toys.

I'll just bung in on my variac to get in the power/current ball-park
before getting more committed to the 60Hz thing.

Though myself a bit of a floydie, primary purpose is for back-line hire
for bands who want "show it off to their buddies" ie audience.

FWIW I have a D28 and Hummingbird going out shortly to The Monkees (or
what is left of them). Dunno if that's something to skite about or not.

geoff

[Scott Dorsey]

geoff wrote:
Anybody know the power/current consumption of an ST-11. I have a USA
version coming and will need to build or source a 110v 60Hz
inverter/whatever supply to run it from 230v 50Hz.

Doesn't mention the power spec in the manual, though it does have
schematic and component list !

I don't know but... I think the only difference between the 50 and 60 Hz
versions was the strobe disc, and you might be able to order a 50 Hz strobe
disc.

If you run it on inverter, that inverter needs to be VERY precisely on
frequency. Crystal control, no free-running oscillator.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[geoff]

On 21/05/2019 12:23 AM, Scott Dorsey wrote:
geoff wrote:
Anybody know the power/current consumption of an ST-11. I have a USA
version coming and will need to build or source a 110v 60Hz
inverter/whatever supply to run it from 230v 50Hz.

Doesn't mention the power spec in the manual, though it does have
schematic and component list !

I don't know but... I think the only difference between the 50 and 60 Hz
versions was the strobe disc, and you might be able to order a 50 Hz strobe
disc.

If you run it on inverter, that inverter needs to be VERY precisely on
frequency. Crystal control, no free-running oscillator.
--scott


Looks like the unit natively runs on a RC-based local oscillator.

The 60Hz mains frequency (x2=120Hz) is only used for the 'Calibrate'
function, and the unit can be calibrated equally well from a precise
musical-note tone.

geoff

[Mike Rivers[_2_]]

On 5/22/2019 1:17 AM, geoff wrote:
Looks like the unit natively runs on a RC-based local oscillator.

The 60Hz mains frequency (x2=120Hz) is only used for the 'Calibrate'
function, and the unit can be calibrated equally well from a precise
musical-note tone.

Did you find a schematic somewhere? I seem to remember mention of a
synchronous motor driving the strobe disk, but that might have been
another model. Seems reasonable, though, to be able to adjust the speed
of the strobe disk so you can "zero" it on an off-pitch piano or an
orchestra that likes to play to an A different from 440 Hz.




--
For a good time, call http://mikeriversaudio.wordpress.com

[Scott Dorsey]

In article , Mike Rivers wrote:
On 5/22/2019 1:17 AM, geoff wrote:
Looks like the unit natively runs on a RC-based local oscillator.

The 60Hz mains frequency (x2=120Hz) is only used for the 'Calibrate'
function, and the unit can be calibrated equally well from a precise
musical-note tone.

Did you find a schematic somewhere? I seem to remember mention of a
synchronous motor driving the strobe disk, but that might have been
another model. Seems reasonable, though, to be able to adjust the speed
of the strobe disk so you can "zero" it on an off-pitch piano or an
orchestra that likes to play to an A different from 440 Hz.

Yes, the ones I have worked on have a synchronous motor, both the tube
ones and the earlier solid state ones, but I haven't worked on any of
the current models. I'm a bit worried about how much an RC oscillator
would drift, but as long as you check it every time you use it, why not?

You could still cal against a 50 Hz signal, it would just be a different
note.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[geoff]

On 23/05/2019 1:20 PM, Scott Dorsey wrote:
In article , Mike Rivers wrote:
On 5/22/2019 1:17 AM, geoff wrote:
Looks like the unit natively runs on a RC-based local oscillator.

The 60Hz mains frequency (x2=120Hz) is only used for the 'Calibrate'
function, and the unit can be calibrated equally well from a precise
musical-note tone.

Did you find a schematic somewhere? I seem to remember mention of a
synchronous motor driving the strobe disk, but that might have been
another model. Seems reasonable, though, to be able to adjust the speed
of the strobe disk so you can "zero" it on an off-pitch piano or an
orchestra that likes to play to an A different from 440 Hz.

Yes, the ones I have worked on have a synchronous motor, both the tube
ones and the earlier solid state ones, but I haven't worked on any of
the current models. I'm a bit worried about how much an RC oscillator
would drift, but as long as you check it every time you use it, why not?

You could still cal against a 50 Hz signal, it would just be a different
note.
--scott



Motor driven by the local RC oscillator.

The dedicated CAL function expects a 60Hz mains, but it can be
calibrated from any known source without switching to 'CAL'.

Schematic and parts list are in the user manual ( !!! ).
https://www.dropbox.com/s/bytbnzbvt0...anual.pdf?dl=0

Stability is/was good enough for many significant studios and
musicians/bands/orchestras. But they do warn to calibrate for every
session....

If the mains transformer can't be jumpered for 220vac, I will get a
replacement (available) and find the Rs and Cs to change for 50Hz. And
may as well change all those old resistors with 1% all around, and recap
for good measure.

geoff

[John Williamson]

On 20/05/2019 13:23, Scott Dorsey wrote:
geoff wrote:
Anybody know the power/current consumption of an ST-11. I have a USA
version coming and will need to build or source a 110v 60Hz
inverter/whatever supply to run it from 230v 50Hz.

Doesn't mention the power spec in the manual, though it does have
schematic and component list !

I don't know but... I think the only difference between the 50 and 60 Hz
versions was the strobe disc, and you might be able to order a 50 Hz strobe
disc.

If you run it on inverter, that inverter needs to be VERY precisely on
frequency. Crystal control, no free-running oscillator.

For that really authentic feel, use a 60Hz inverter controlled using a
phase locked loop locked to the local mains frequency. That will give
the genuine variation in tuning over time as the mains frequency drifts
a bit. ;-)


--
Tciao for Now!

John.

[John Williamson]

On 20/05/2019 12:08, geoff wrote:
Anybody know the power/current consumption of an ST-11. I have a USA
version coming and will need to build or source a 110v 60Hz
inverter/whatever supply to run it from 230v 50Hz.

Doesn't mention the power spec in the manual, though it does have
schematic and component list !

geoff

I've just looked at the circuit diagram, and it seems the unit works by
using a local RC oscillator, which is divided in frequency under the
control of the diode matrix and ICs according to the settings of the
note selector knob to drive a synchronous motor attached to the strobe
disc at a variable speed. The light is flashed at audio frequency by a
transistor driven into saturation once per cycle of the input frequency.
The combination of the differing strobe disc speeds and the audio
frequency flashing of the neon gives stationary patterns at the various
note frequencies, with the differing rings being more clearly visible at
different octaves.

As such, the tuning is independent of the mains frequency, and the only
time the mains frequency is relevant is when the unit is being calibrated.

So, the disc and all the electronics are exactly the same for 50 and 60
Hz machines. The only caveat will be that the power transformer *may* be
designed for 60 Hz, and you may need a different one for 50 Hz, even at
110 Volts, as the lower frequency may cause it to overheat. Subject to
that caveat, use a 60 Hz reference tone for calibration fed in to the
mic input from a signal generator, and you'll be fine. To get the right
voltage, use a site dropper transformer, which gives 110 Volts at the
output from a 230 volt input. Available ex stock from any builders'
merchant in the UK for about seventy pounds sterling plus twenty or so
for the plugs and sockets needed to connect it.

Another alternative is to import a 110 V 60 Hz inverter as used in many
American RVs and boats, and power that off a lead acid battery which
will give about 10 minutes of use per amp hour of capacity. A 150 watt
inverter should be big enough, but make sure it is pure sine wave, not
modified, as the modifoed sine wave will generate interference on the
electronics, and may damage the power transformer.

--
Tciao for Now!

John.

[geoff]

On 24/05/2019 1:09 AM, John Williamson wrote:
On 20/05/2019 12:08, geoff wrote:
Anybody know the power/current consumption of an ST-11. I have a USA
version coming and will need to build or source a 110v 60Hz
inverter/whatever supply to run it from 230v 50Hz.

Doesn't mention the power spec in the manual, though it does have
schematic and component list !

geoff

I've just looked at the circuit diagram, and it seems the unit works by
using a local RC oscillator, which is divided in frequency under the
control of the diode matrix and ICs according to the settings of the
note selector knob to drive a synchronous motor attached to the strobe
disc at a variable speed. The light is flashed at audio frequency by a
transistor driven into saturation once per cycle of the input frequency.
The combination of the differing strobe disc speeds and the audio
frequency flashing of the neon gives stationary patterns at the various
note frequencies, with the differing rings being more clearly visible at
different octaves.

As such, the tuning is independent of the mains frequency, and the only
time the mains frequency is relevant is when the unit is being calibrated.

So, the disc and all the electronics are exactly the same for 50 and 60
Hz machines. The only caveat will be that the power transformer *may* be
designed for 60 Hz, and you may need a different one for 50 Hz, even at
110 Volts, as the lower frequency may cause it to overheat. Subject to
that caveat, use a 60 Hz reference tone for calibration fed in to the
mic input from a signal generator, and you'll be fine. To get the right
voltage, use a site dropper transformer, which gives 110 Volts at the
output from a 230 volt input. Available ex stock from any builders'
merchant in the UK for about seventy pounds sterling plus twenty or so
for the plugs and sockets needed to connect it.

Yep - all of the above already.

Might be worth considering as a simple project popping in a stable and
precise oscillator.


Another alternative is to import a 110 V 60 Hz inverter as used in many
American RVs and boats, and power that off a lead acid battery which
will give about 10 minutes of use per amp hour of capacity. A 150 watt
inverter should be big enough, but make sure it is pure sine wave, not
modified, as the modifoed sine wave will generate interference on the
electronics, and may damage the power transformer.



That power side of things already thought of and considered too messy.
Marginal gain through having 60Hz power as a target. Will see if the
xformer is, as the schem suggests, in reality strappable for 220v.

geoff

[gray_wolf]

On 5/23/2019 3:03 PM, geoff wrote:
On 24/05/2019 1:09 AM, John Williamson wrote:
On 20/05/2019 12:08, geoff wrote:
Anybody know the power/current consumption of an ST-11. I have a USA version
coming and will need to build or source a 110v 60Hz inverter/whatever supply
to run it from 230v 50Hz.

Doesn't mention the power spec in the manual, though it does have schematic
and component list !

geoff

I've just looked at the circuit diagram, and it seems the unit works by using
a local RC oscillator, which is divided in frequency under the control of the
diode matrix and ICs according to the settings of the note selector knob to
drive a synchronous motor attached to the strobe disc at a variable speed. The
light is flashed at audio frequency by a transistor driven into saturation
once per cycle of the input frequency. The combination of the differing strobe
disc speeds and the audio frequency flashing of the neon gives stationary
patterns at the various note frequencies, with the differing rings being more
clearly visible at different octaves.

As such, the tuning is independent of the mains frequency, and the only time
the mains frequency is relevant is when the unit is being calibrated.

So, the disc and all the electronics are exactly the same for 50 and 60 Hz
machines. The only caveat will be that the power transformer *may* be designed
for 60 Hz, and you may need a different one for 50 Hz, even at 110 Volts, as
the lower frequency may cause it to overheat. Subject to that caveat, use a 60
Hz reference tone for calibration fed in to the mic input from a signal
generator, and you'll be fine. To get the right voltage, use a site dropper
transformer, which gives 110 Volts at the output from a 230 volt input.
Available ex stock from any builders' merchant in the UK for about seventy
pounds sterling plus twenty or so for the plugs and sockets needed to connect it.

Yep - all ofÂ* the above already.

Might be worth considering as a simple project popping in a stable and precise
oscillator.


Another alternative is to import a 110 V 60 Hz inverter as used in many
American RVs and boats, and power that off a lead acid battery which will give
about 10 minutes of use per amp hour of capacity. A 150 watt inverter should
be big enough, but make sure it is pure sine wave, not modified, as the
modifoed sine wave will generate interference on the electronics, and may
damage the power transformer.



That power side of things already thought of and considered too messy. Marginal
gain through having 60Hz power as a target. Will see if the xformer is, as the
schem suggests, in reality strappable for 220v.

geoff


Nobody uses tuning fork anymore? The battery lasts forever.

[geoff]

On 24/05/2019 12:46 PM, gray_wolf wrote:



Nobody uses tuning fork anymore? The battery lasts forever.


I've got one. Somewhere. Changes pitch with temperature. Not very
visual. Dents guitar lacquer ;-)

geoff

[Phil Allison[_4_]]

geoff wrote:




Nobody uses tuning fork anymore? The battery lasts forever.


I've got one. Somewhere. Changes pitch with temperature.



** How silly, so does everything.

Tuning forks are very stable, used in Boliva watches and older guitar tuners from Roland.



..... Phil

[polymod]

"gray_wolf" wrote in message ...

snip

Nobody uses tuning fork anymore? The battery lasts forever.

I do! I have customers that insist no tuning aids be used but a fork.
For quick work I also have an original Hale Sight-O-Tuner from the old
Tuner's Supply House.

Poly


---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

[[email protected]]

geoff:

Is "Conn" the brand name? I cannot seem to
find out anything about them on the internet
when I Googled the term.

[MiNe109]

On 5/26/19 10:35 AM, wrote:
geoff:

Is "Conn" the brand name? I cannot seem to
find out anything about them on the internet
when I Googled the term.

Try conn strobotuner. They were formerly commonplace in high school
bandrooms.

http://www.terrysmythe.ca/st-6.htm

Stephen

[[email protected]]

MiNe109:

Thanks! Clears everything up. I will definitely read that
manual and study the history of Conn Corpp.

[geoff]

On 27/05/2019 4:17 AM, wrote:
MiNe109:

Thanks! Clears everything up. I will definitely read that
manual and study the history of Conn Corpp.


Here's one in the background, in front of the bass:
https://youtu.be/cUNPEE7taAY?t=73

geoff

[geoff]

On 27/05/2019 3:43 AM, MiNe109 wrote:
On 5/26/19 10:35 AM, wrote:
geoff:

Is "Conn" the brand name?Â* I cannot seem to
find out anything about them on the internet
when I Googled the term.

Try conn strobotuner. They were formerly commonplace in high school
bandrooms.

http://www.terrysmythe.ca/st-6.htm

Stephen


Or he

http://bfy.tw/Npvp

Um, a bit more that high-school bandrooms. And still nice stage
furniture (or more than that) if you are David Gilmour and many others.

geoff