开云体育

Hi all,

There used to be such a thing as an electromechanical chopper (AKA
vibrator), kind of like a relay tuned to operate at many 100's of Hz,
or faster. Airpax was a popular manufacturer. Tek used them in some
instruments (for example, part #119-0016-00), and I have a need for
one of fairly relaxed specs. Of course, I'd like to spend a little
money as possible. If you have one, please email me OFFLIST - thanks!

This will go into a piece of Tek-related equipment, by the way, if
that helps :)

Chris,


Maybe this is unnecessary, but there is a wide variety of the things
(I'd guess hundreds of types at a minimum). There are different coil
voltages, frequencies, contact arrangements, contact types, and
connection layouts (at least). Also, a chopper is not the same as a
vibrator. (the former is driven and for low level signals, the latter
self oscillating and for power.)

Also, if this is a new design, you really should consider using a FET
switch instead.

-John

There are ppl that devolops video camera adapters, where you can mount a
normal 35mm system camera lens to a videocamera, and get the focus depth
used in filmmaking (background softed, impossible with videocameras) Its
spelndid when you want to attend the viewer of details in the film that are
imortant for a story etc.



Thing is that the image created by the lens is projected on a “screen”
inside a lightproof tube, and the video records the image,m that now is
upside down and mirrired.



Now to the point.



A drawback is that the videocamera gets any surface patterns from that white
transparent screwn, dust etc, like a static background in the produced film.

The solution is to use a vibrator, and they often use a beeper, that device
ppl use instead of telephones. And they mount them inside the tube with an
ackumulator that is rechargable. The tube vibrates during takes, and you
cannot see anything but the nice film content.



So my hint is to use that device =)



Ref:





/Lars







-----Ursprungligt meddelande-----
Fr?n: TekScopes@... [mailto:TekScopes@...] F?r J
Forster
Skickat: den 29 december 2006 22:52
Till: TekScopes@...
?mne: [TekScopes] Chopper wanted (the electromechanical kind)




Hi all,

There used to be such a thing as an electromechanical chopper (AKA
vibrator), kind of like a relay tuned to operate at many 100's of Hz,
or faster. Airpax was a popular manufacturer. Tek used them in some
instruments (for example, part #119-0016-00), and I have a need for
one of fairly relaxed specs. Of course, I'd like to spend a little
money as possible. If you have one, please email me OFFLIST - thanks!

This will go into a piece of Tek-related equipment, by the way, if
that helps :)

Chris,

Maybe this is unnecessary, but there is a wide variety of the things
(I'd guess hundreds of types at a minimum). There are different coil
voltages, frequencies, contact arrangements, contact types, and
connection layouts (at least). Also, a chopper is not the same as a
vibrator. (the former is driven and for low level signals, the latter
self oscillating and for power.)

Also, if this is a new design, you really should consider using a FET
switch instead.

-John





[Non-text portions of this message have been removed]

-------- Original-Nachricht --------
Datum: Fri, 29 Dec 2006 22:03:55 -0500
Von: Christian Weagle <cweagle@...>
An: "faustian.spirit" <faustian.spirit@...>
Betreff: Re: Chopper wanted (the electromechanical kind)

faustian.spirit wrote:

I always wonder what the difference to wiring a relay into a self
exciting circuit is...

That would work for very small relays, and slowly, but I think there is
mechanical tuning required for 1 KHz operation. But don't quote me on
that.

Actually tried that recently when I was bored... took a small print relay (not really miniature, probably a reed type internally.) What I got was around 10kHZ - don't know how long it will survive that :) Also, a reverse Diode is important... without, the whole thing behaves very wildly...
--
Der GMX SmartSurfer hilft bis zu 70% Ihrer Onlinekosten zu sparen!
Ideal f???r Modem und ISDN:

faustian.spirit wrote:

I always wonder what the difference to wiring a relay into a self
exciting circuit is...

That would work for very small relays, and slowly, but I think there

is

mechanical tuning required for 1 KHz operation. But don't quote me on

that.

Actually tried that recently when I was bored... took a small print
relay (not
really miniature, probably a reed type internally.) What I got was
around 10kHZ -
don't know how long it will survive that :) Also, a reverse Diode is
important...
without, the whole thing behaves very wildly...

A small relay won't last long in this application. If it was running at
10 KHz, the contacts were likely not opening very far. A vibrator often
has a significant mass on the armature to make it a truly resonant mass
spring assembly with fairly light damping. They operate in a limit cycle
oscillation with the stops being the NO and NC contacts. There is an
excellant reference (the Mallory Vibrator Guide) here:



The file is PW protected. Please read and follow the directions on the
site for requesting the manual-specific PW.

Choppers also are resonant, but are generally much smaller and lighter.
I think they too are lightly damped and are overdriven to ensure good
contact pressure.

-John