Why are transparent trimpots so rare?

In general, no. The instant you have one or more trim-pots on a circuit board the skill requirements for some of the production workers goes up significantly. I have found that this can lead to a lot of problems.

It might still have been made in Japan. There companies usually have access to a large pool of skilled employees.

When I click on live-video links on there site nothing happens :-(

On a sunny day (Mon, 11 Dec 2006 20:10:33 GMT) it happened Joerg wrote in :

It works here, do you have a media player that launches? I am watching it in Linux Firefox with mplayer plugin.

If _nothing_ goes it is possible they test for country of origin, but France24 was ment for international audience, so it _should_work?

Works fine for me(XP SP2 2.7GHZ , firefox 1.5.0.8)

That's what Deutsche Welle TV does. It blocks US viewers. But at least then I'd expect some courtesy message to appear. Especially since they also have an "Amerique" tab.

Is that the special "Entertainment for Americans" comic video of an English donkey named Graham that's getting his nuts poked with a high-voltage prod every time he utters something un-American, which he does very often? Quite entertaining.

Could you please elaborate on that?

Thank you.

I have, on occasion, used two single-turn pots for course and fine adjustment of a parameter.

As for temperature and plastics:

Typical Deflection Temperatures of Polymers at 0.46 MPa (degrees C)

Polyethylene Terephthalate (PET)......70 Acrylic...............................95 Polyethylene, HDPE....................85 Polystyrene...........................95 ABS...................................98 Polypropylene........................100 Polycarbonate........................140 ABS + 30% Glass Fiber................150 Acetal Copolymer.....................160 Nylon 6..............................160 Polypropylene + 30% Glass Fiber......170 Acetal Copolymer + 30% Glass Fiber...200 Nylon 6 + 30% Glass Fiber............220 PET + 30% Glass Fiber................250

Guy Macon

You can use these as controllable resistors. Because of their extremely low capacitances they are quite suitable to control the amplitude of signals way into the UHF range. So could pin diodes but it is harder to servo those (done it as well, though...).

Servo means you have one FET in the RF path and that is controlled at the gate by an opamp output. Another FET of same type is in the feedback path so that you can actually set the resistance in a linear fashion because the opamp now regulates away the non-linearity of Vgs versus Rdson. With some nifty choke tricks you can also use the very same FET that acts as the "RF potmeter" for feedback but that requires a great familiarity with RF stuff. This would be required if lot to lot tolerances are too much to stomach.

Dual-gates were never meant to be used that way I guess but heck, a BF998 can be had for under a dime in qty. Always looking for a bargain here :-)

If you don't want to servo you can somewhat linearize it by feeding back half of the drain signal to one of the gates. IIRC that is also explained somewhere in AoE.

Dual gates can, of course, also be used in the standard configuration where you feed the RF into one gate and regulate the gain via the other. But dynamic range isn't always that great when doing this.

Of course, then there is software...

A former boss of mine told the story of a smart munition they were testing, and artillery shell that was supposed to seek an armored target. It worked great in the lab, and in their tests, and when it came time to do the official demonstration tests for the military, he had all the programming connectors cut off, and strictly announced "No Changes!"

Came the day of the test, they fired the shell, and it zigged left when it should have zagged right. They failed and lost the contract.

During the investigation afterwards, one of the software engineers said "It shouldn't have done that! The update I did didn't touch that code..."

Update? What update?

Why, the update I did the night before the test. I had this great idea, but you wouldn't believe how long it took me to solder on new connectors so I could re-progam the thing...

Moral of the story: You can make something fool proof, but you can't make it damn fool proof!

Charlie

Guy Macon wrote in news:Ev2dnSbkQqpL5- snipped-for-privacy@giganews.com:

Is PET dramatically unusual in combination with glass fibre, or is that top one meant to be lower, with value 170?

What's really frustrating is when your desired set point is between two windings on a wirewound. At this one lab, the boss would ask, "Is that in-fine-ite-ly variable?" and, sadly, I'd have to answer "no." It's too bad that the R&D departmant at the company were such idiots - when it's that sensitive, they should have used a much smaller value pot, with a fixed resistor at either end, as needed.

Cheers! Rich

I once worked at a place that made, essentially, a SEM. The display, voltage, focus, magnification etc. was all digital, controlled with pushbuttons. One day, the boss was trying to focus in on some sample, using those stupid buttons, and he said, "I'd rather have a knob."

Cheers! Rich

I can say, "zaadvragende ogen." ;-)

Cheers! Rich

That shouldn't be hard - just use two stators and a semicircular rotor:

Would that give you what you want?

Cheers! Rich

Hi Rich,

This link isn't working, but from what you describe...

Yes it would... although I'd be wanting it in a tiny package too! :-)

You might try it again - I just realized that the last time I rebooted my server, I forgot to reset the DNS and httpd.conf.

It's just two rectangles side-by-side, with a semicircular plate superimposed.

Cheers! Rich

Still not working (8:12AM on the west coast, Thursday).

abiengr.com resolves to 71.103.105.212 but pings don't respond either. :-)

This is frustrating. I'm on a dynamic IP, so every time I reboot I have to log onto

FWIW, I've just restarted apache, 6 PM PST, Thur, 12/14/06.

Thanks, Rich