Does anyone know if anti-log pots are more prone to failure? I bought
an old vintage broadcast radio that has separate bass and treble
controls and for some reason they've used an anti-log pot for the
treble - and it doesn't do nothing. Apart from that, the radio seems
fine so I'd like to get it fixed. I've never encountered 'anti-log'
pots before (never even heard of them) and am just curious as to if
they're more likely to fail.
No more so than any other pot - just a tad more difficult to make. Point of the choice, initially, was to make the pot travel more linear to the human ear, vs. electrically. They are easily obtained in most common values, other than the fact that theBrits, like the French, when they made their electronics copied no one, and no one copied them.
I would first try cleaning the pot. I do not know how the treble-circuit is designed in that radio - other than the pot-resistor wants to be in-circuit in many designs, so it could be as simple as something in the wiper. Further, if the overall potvalue and current-handling capacity is correct, the only difference between OEM and a replacement - anti-log or not - would be the response-to-travel perception.
Peter Wieck
Melrose Park, PA
Thanks. I came across the relevant schematic fragment online showing
the tone controls for bass and treble. I can't see how they work
unless they form some sort of elementary network with the 2.5uF C11.
Hard to say with those pesky sockets in the way of the signal path.
It's about a third of the way down the page in this document:
https://www.microscopy-uk.org.uk/mag/artjan13/iw-radio2.html
Does anyone know if anti-log pots are more prone to failure?
I bought
an old vintage broadcast radio that has separate bass and treble
controls and for some reason they've used an anti-log pot for the
treble - and it doesn't do nothing.
Apart from that, the radio seems
fine so I'd like to get it fixed. I've never encountered 'anti-log'
pots before (never even heard of them) and am just curious as to if
they're more likely to fail.
In article <cvojlgdenm5kj60jajnsubdkj5937f8vrm@4ax.com>, cw9877@gsm.com >says...
Thanks. I came across the relevant schematic fragment online showing
the tone controls for bass and treble. I can't see how they work
unless they form some sort of elementary network with the 2.5uF C11.
Hard to say with those pesky sockets in the way of the signal path.
It's about a third of the way down the page in this document:
https://www.microscopy-uk.org.uk/mag/artjan13/iw-radio2.html
From the looks of things there is no way to tell how the base and tresle >controls work. They are shown to go into the block diagram to the right
of the 2 batteries. There could be anything in that block.It is
doubtful that the C11 has anything to do with the 2 pots.
So the taper should not make any difference in the life of a pot.
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