Narrow-Bandwidth Television Association

Here are the latest pictures of my MUTR unit. Many modifications, take a look...

Back

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Relocation and replacement of the brightness and sync control

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The new 10k pots have a nice smooth control!!

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The new sound area, sound card, speaker and 10k volume control.

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Two screen captures. Please excuse the grain effect, I need to find a new diffuser...

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I use a mains power supply as the battery pack can run down quickly and helps to give sync problems. I use an amplified loudspeaker (Philips) from an old computer sound card output. I replaced the diffuser with a piece of stiff drafting film as sold for making printed circuits photographically.

Nice modifications (Manufacturer Take Note)
Try a smoother diffuser material - the picture quality gain is well worth the simple modification

I tried the "Scotch Magic Tape over the holes diffuser" tip from elsewhere on this forum on my MUTR and found it worked as well as anything else I tried - for simplicity it is hard to beat.

So, are both pots 10K linear?

Can anyone indicate?

Thanks,

John Lemke

The vast majority of pots are linear, the exception (generally) is where they're used as a volume control where they should be log. But either flavour will work, just the 'feel' or 'action' will be different. But no harm done to the gear...

There are the occasional applications where an odd type of pot is specified, like an anti-log pot, rare and I would say almost impossible to find.

As for the resistance value (10k), I can't help there...use whatever it says on the diagram...in a lot of cases it wouldn't matter too much if it were different, it all depends on the circuit design...

In the links above 10k pots are mentioned, so that's what I would go for...that's without having a circuit diagram to look at...

Steve A.

Thank you, Steve!

The pots I buy here are marked either 10kA or 10kB, (using 10k as an example) the way I remember which is which is 10kA=Audio (a volume control, log),10kB=Bloody well everything else! (Linear).

Steve A.

Though those in the attached photo are marked A10k and B10k...it's still the same idea...

Other manufacturers may put LOG. or LIN. which is a bit more helpful...

Photo taken with my cheap Vivo dumbphone, not bad for something that costs less than 25% of an Apple or a Samsung...wide aperture, hence the limited depth of field...the laws of optics which no manufacturer can get around...but it focused on the right part, not the shaft end which most would aim for...

As far as I remember the A-type of potentiometers are the common linear ones, while the B-types are the exeptional ones: logarithmic. It is the B-type that is used as volume control for audio. Because our ears have a logarithmic sensitivity, that is you experience an increase in loudness of a factor 2 the same for low volumes as for high volumes, that a logarithmic control is much easier to handle. If you place a linear potmeter in that function, you will hear that all the control range is at the beginning (left) of the rotation. After turning it up one quarter the sound is loud and the remaining rotation of the spindle does hardly something (for your perception).

So in (almost) any function other than sound volume control: use a linear potentiometer.

The Chinese are at it again. I've just measured the two pots in the photo above, the 10kA is definitely Log., and the 10kB is definitely Lin. Oh well, whatever happened to standards and conventions? I haven't used a panel-mounted pot in quite some time, so I thought I'd check in case I had it wrong...it seems for these ones I was correct (for once).

Steve A.

I have been looking to do this with my 'Televisor'. Thankyou for putting this on here. It has given me inspiration!!