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F Knobs vs F Buttons on Signal Generators

D

D from BC

There's no freq. knobs on some signal generator models. :(

I bet elec. experimenters go for generators with a BIG frequency
control dial. DDS too.

Fully buttonized generators are like setting a microwave oven or
digital clock.
I'm afraid I'll be pecking at the buttons like a woodpecker..

Anybody regret getting a signal generator with only buttons, no knobs?


D from BC
 
L

Leon

There's no freq. knobs on some signal generator models. :(

I bet elec. experimenters go for generators with a BIG frequency
control dial. DDS too.

Fully buttonized generators are like setting a microwave oven or
digital clock.
I'm afraid I'll be pecking at the buttons like a woodpecker..

Anybody regret getting a signal generator with only buttons, no knobs?

D from BC
Click to expand...

My old Marconi 2019A units have up/down buttons, as well as the
keypad.

Leon
 
J

john jardine

D from BC said:
There's no freq. knobs on some signal generator models. :(

I bet elec. experimenters go for generators with a BIG frequency
control dial. DDS too.

Fully buttonized generators are like setting a microwave oven or
digital clock.
I'm afraid I'll be pecking at the buttons like a woodpecker..

Anybody regret getting a signal generator with only buttons, no knobs?


D from BC
Click to expand...

For development work, buttons (like surface mount components), are a grade
#1 PITA. Human friendly alternatives make use of the expensive and lost art
of mechanical engineering.
I like the spin wheel on my Racal synth. Must be 2Ibs of metal in the
flywheel.
Best for me is a sig gen based on a magnificently engineered, anti-backlash
geared, ball-raced, 2 gang air spaced capacitor, assembled with a high
kilopoise lubricant. Seems to have near infinite setability and ineffable
smoothness.
 
D

D from BC

For development work, buttons (like surface mount components), are a grade
#1 PITA. Human friendly alternatives make use of the expensive and lost art
of mechanical engineering.
I like the spin wheel on my Racal synth. Must be 2Ibs of metal in the
flywheel.
Best for me is a sig gen based on a magnificently engineered, anti-backlash
geared, ball-raced, 2 gang air spaced capacitor, assembled with a high
kilopoise lubricant. Seems to have near infinite setability and ineffable
smoothness.
Click to expand...

Gee... I just got an idea what it takes for a good frequency control
knob.
No wonder the signal generator designers make units with only control
buttons. It's cheaper and simpler than a knob. :p


D from BC
 
F

Frank Buss

D said:
There's no freq. knobs on some signal generator models. :(

I bet elec. experimenters go for generators with a BIG frequency
control dial. DDS too.
Click to expand...

Most of the time you have a laptop or PC at hand and then you can use a
mouse and a keyboard for frequency changes, like I've implemented in
http://www.frank-buss.de/SignalGenerator/ .

But I have a very nice optoelectronic encoder here (
http://www.megatron.de/export/Encoder/M101B/DB_M101B_engl.pdf ), which I
plan to integrate, too, which will be read from the software. Then you can
focus the value you want to change with the mouse (e.g. frequency or duty
cycle) and adjust the value with the knob.
 
J

Joel Koltner

Frank Buss said:
But I have a very nice optoelectronic encoder here (
http://www.megatron.de/export/Encoder/M101B/DB_M101B_engl.pdf ), which I
plan to integrate, too, which will be read from the software. Then you can
focus the value you want to change with the mouse (e.g. frequency or duty
cycle) and adjust the value with the knob.
Click to expand...

If you don't want to roll this all yourself, you might use a Griggin
Powermate: http://www.griffintechnology.com/products/powermate . It's quite
popular with the GnuRadio and FlexRadio guys as a tuning knob...

---Joel
 
E

Ecnerwal

Two of the buttons are up/down. On the particular model I have, you can
set the cursor to a digit, and it runs that digit up/down (and the ones
to the left if you keep going). Along with a wide array of sweep
options, it works for me.

You could do lots of nice stuff with a rotary encoder and speed
sensitivity (change faster as it's spun faster - change slower as it's
turned slowly). Follow the lead of snooty stereos and make the knob from
solid metal for nice heft. Put a GPIB interface on it and you can plug
it into mine ;-)

As for generators where the knob IS the frequency setting, and you have
to fiddle with where the knob is (within a 270 degree arc, hard-mapped
to output) to get a specific frequency, yuck.
 
J

Jan Panteltje

Gee... I just got an idea what it takes for a good frequency control
knob.
No wonder the signal generator designers make units with only control
buttons. It's cheaper and simpler than a knob. :p


D from BC
Click to expand...

I have a transmitter with both a dial and push buttons to set either Hz, 10Hz,
100Hz etc.
Both are very useful.
Problem with the dial is that it sometimes skips steps, so you really
have to look at the display (the dial clicks, but the clicks are not reliable
steps).
The dial is nice for playing around, checking.
 
B

Ben Jackson

Gee... I just got an idea what it takes for a good frequency control
knob.
No wonder the signal generator designers make units with only control
buttons. It's cheaper and simpler than a knob. :p
Click to expand...

If you look at the prices of encoders there's the class that goes up to
about 36 counts per turn (~$5, typically mechanical) and the class that
goes up to hundreds (~$50, typically optical). The low-count ones are
terrible for inputs that require both high precision and large gross
movements (like frequency).

The best homebrew compromise to buying an expensive optical encoder is
to tear up an old mouse and use one of its optical encoders. I think
there are also high-res encoders in VCR heads, which come with nice metal
"knobs". ;-)
 
A

[email protected]

Gee... I just got an idea what it takes for a good frequency control
knob.
No wonder the signal generator designers make units with only control
buttons. It's cheaper and simpler than a knob. :p

D from BC
Click to expand...

Can you use music-style control knobs and get them to control your
GPIB/USB chain?
I use a Nostromo game pad with its software to control my CAD programs.
 
J

Jan Panteltje

On a sunny day (Fri, 04 Jan 2008 18:19:50 -0600) it happened Ben Jackson
there are also high-res encoders in VCR heads,
Click to expand...

I am not aware of that, would be nice though.
There is a one revolution tach, and position info is obtained from the
head signals.
Some old Philips helical scan cassete players used piezo actuators to
correct head position.
The mass of the head drum is so big (your big knob) that you cannot
change its speed a lot in one revolution.
 
E

[email protected]

Two of the buttons are up/down. On the particular model I have, you can
set the cursor to a digit, and it runs that digit up/down (and the ones
to the left if you keep going). Along with a wide array of sweep
options, it works for me.

You could do lots of nice stuff with a rotary encoder and speed
sensitivity (change faster as it's spun faster - change slower as it's
turned slowly). Follow the lead of snooty stereos and make the knob from
solid metal for nice heft. Put a GPIB interface on it and you can plug
it into mine ;-)

As for generators where the knob IS the frequency setting, and you have
to fiddle with where the knob is (within a 270 degree arc, hard-mapped
to output) to get a specific frequency, yuck.
Click to expand...

I've made some rotary knobs using an hp 200 pulse rotary encoder, a
1/4-inch thick x 2-inch diameter piece of aluminum on the shaft for
inertia and some (switchable) external logic to divide down the pulses
for fine tuning. The large disk gives it a nice feel. It turns
smoothly and I can give it a strong twist to rapidly get the display
to near where I want it to be.
al
 
J

Joel Koltner

JeffM said:
Since you mentioned GnuRadio,
I find it interesting that Griffin specifies compatibility with XP &
OS X
--but nothing Open Source.
Click to expand...

Yeah, sad but not too surprising...

If I had to guess, I would say that Griffin powermate is probably just a USB
HID-type device, so it's likely very easy (for someone familiar with USB HID
devices under Linux) to get it working... it might even "just work" right out
of the box.

I have one of those cool little Apple aluminum Bluetooth keyboards and I've
only ever used it with Windows and Linux boxes -- it's never "spoken" to a
Real Apple computer yet, even though it's only advertised as being compatible
with them.

Interface standards are a good thing...
 
N

Nico Coesel

D from BC said:
There's no freq. knobs on some signal generator models. :(

I bet elec. experimenters go for generators with a BIG frequency
control dial. DDS too.

Fully buttonized generators are like setting a microwave oven or
digital clock.
I'm afraid I'll be pecking at the buttons like a woodpecker..

Anybody regret getting a signal generator with only buttons, no knobs?
Click to expand...

I wouldn't even touch a frequency generator that hasn't a rotary knob
to set the frequency.
 
N

Nico Coesel

Ben Jackson said:
If you look at the prices of encoders there's the class that goes up to
about 36 counts per turn (~$5, typically mechanical) and the class that
Click to expand...

That expensive? I'm quite sure they can be found much cheaper. 36
counts per turn is fine. Software can determine the actual number of
steps depending on the speed.

For hobby purposes, one can also use an old stepper engine from a 5
1/4" floppy drive.
 
D

D from BC

That expensive? I'm quite sure they can be found much cheaper. 36
counts per turn is fine. Software can determine the actual number of
steps depending on the speed.

For hobby purposes, one can also use an old stepper engine from a 5
1/4" floppy drive.
Click to expand...


Do you mean using the entire stepper motor?
One detects and decodes the pulses from the drive coils?


D from BC
 
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