Hi I am wondering if lets say you have a normal audio pot with two "channel"
Both channels is constructed as normal logarithmic audio pot.
Is it possible to let channel one act normal and channel two act as a reverse audio pot, just by switching the wires on channel two?
Both channels is constructed as normal logarithmic audio pot.
Is it possible to let channel one act normal and channel two act as a reverse audio pot, just by switching the wires on channel two?
LOL thanks, that could even I understand.
I have let me tell that if you take a pot two liniar channels and connect outer most from one channel to the center tab on the second, you've got a perfect-ish logarithmic pot. Is that true?
Is that maybe a way to make a both forward and reverge log pot?
I have let me tell that if you take a pot two liniar channels and connect outer most from one channel to the center tab on the second, you've got a perfect-ish logarithmic pot. Is that true?
Is that maybe a way to make a both forward and reverge log pot?
I can't imagine what you are describing but you can easily fake a log pot from a linear one... and so you should be able to then do what you suggest of reversing one.
Figure 8 here. You could use a dual gang linear pot:
Potentiometers (Beginners' Guide to Pots)
Also:
ESP - A Better Volume Control
Figure 8 here. You could use a dual gang linear pot:
Potentiometers (Beginners' Guide to Pots)
Also:
ESP - A Better Volume Control
Thank you a lot! Funny enough is there a description in the second link you send, as Figure 5 - Log Approximation Using Dual-Gang Pot.
But would that not demand two gangs per channel?
But would that not demand two gangs per channel?
thanks, in that picture I pointed to, does it show a normal log pot, how would a reverse log be connected?
Short answer: faking Log pots is very poor Engineering, if it even deserves that name.
There is a reason Log pots are still being made and specified.
There is a reason Log pots are still being made and specified.
They are linear pots.
It's hard visualise what you mean tbh. A reverse log pot which I think you mentioned at the start of the thread to me means a pot that just works back to front.
Figure 9 here. Isn't this what you mean and this is done with linear pots:
Potentiometers (Beginners' Guide to Pots)
Sorry my English skills! I'd try to explain in a better way.
Imagine the curve a audio pot makes, imagine you had a LED's connected to the pot, how the LED would dimm.
Then imaging have a second "reverse log" pot, also with a LED.
Now, no matter how you turn the combined pot / rev pot, both LED's combined lumen will stay the same.
So at high volume do one LED get bright while the other LED is barely visible and at low volume is it the opposite.
Hope it makes sense?
Imagine the curve a audio pot makes, imagine you had a LED's connected to the pot, how the LED would dimm.
Then imaging have a second "reverse log" pot, also with a LED.
Now, no matter how you turn the combined pot / rev pot, both LED's combined lumen will stay the same.
So at high volume do one LED get bright while the other LED is barely visible and at low volume is it the opposite.
Hope it makes sense?
Channel One will raise Volume, Channel B will attenuate Volume.
The problem is Led's aren't linear, but could work with lamps perhaps.
The problem is, we don't understand what You are trying to do.
Can You be more specific ?
Sorry forgot to answer about log pots being better then what you can make yourself.
I do believe that, but I read the article that Mooly links to and it postulates that most log pots are fare from logarithmic, it's only if you give out BIG money that you may get something remotely logarithmic. It recommend other solutions that should be a lot better.
I do believe that, but I read the article that Mooly links to and it postulates that most log pots are fare from logarithmic, it's only if you give out BIG money that you may get something remotely logarithmic. It recommend other solutions that should be a lot better.
Yes LED's aren't linear, I know, had just no better example.
I just want to build something that taste a bit like the lightspeed volume control.
He uses a log + rev log. to let two optocouplers act in reversal of each other.
I just want to build something that taste a bit like the lightspeed volume control.
He uses a log + rev log. to let two optocouplers act in reversal of each other.
Why not just build a quick test circuit 🙂
Use a linear pot and fake a log law and do the same for the other gang in reverse.
Feed the pots with say 12 volts and take the output of each to a buffer/opamp stage that can drive your LED's. You could even try a single transistor as an emitter follower buffer.
Use a linear pot and fake a log law and do the same for the other gang in reverse.
Feed the pots with say 12 volts and take the output of each to a buffer/opamp stage that can drive your LED's. You could even try a single transistor as an emitter follower buffer.
Yes you are right! 🙂
But may I ask you what you would recommend of general components to get, to learn from?
I mean PNP and NPN of cause but name of standard components everybody should have, like the 2N2222, what about Caps, FET's and so on?
But may I ask you what you would recommend of general components to get, to learn from?
I mean PNP and NPN of cause but name of standard components everybody should have, like the 2N2222, what about Caps, FET's and so on?
I always used to have a full range of resistors, 10 of every E12 value as a minimum, the E24 series will give you more values.
Lots of general purpose transistors which for me were always BC types like BC546 and the PNP equivalents. BD131 and BD132's, TIP41 and TIP42. These are all great for experimenting with.
A decent selection of electrolytic caps in the 1uF to 1000uF range and also some film caps in the 0.01uF to 0.22uF range.
Some cheap ceramics of 1pF upward to 1nF
Common opamps like 741's and 4558's and FET versions such as TL071 and 72's.
FET transistors I would go for 2N3819 and J112's with perhaps some P channel equivalents.
Some IRF240 and 9240 power FET's.
Lots of LED's and a few presets from 100 ohm to 1meg.
It's a never ending list 🙂
Lots of general purpose transistors which for me were always BC types like BC546 and the PNP equivalents. BD131 and BD132's, TIP41 and TIP42. These are all great for experimenting with.
A decent selection of electrolytic caps in the 1uF to 1000uF range and also some film caps in the 0.01uF to 0.22uF range.
Some cheap ceramics of 1pF upward to 1nF
Common opamps like 741's and 4558's and FET versions such as TL071 and 72's.
FET transistors I would go for 2N3819 and J112's with perhaps some P channel equivalents.
Some IRF240 and 9240 power FET's.
Lots of LED's and a few presets from 100 ohm to 1meg.
It's a never ending list 🙂
Thank you a lot🙂 No I imagine that no matter how many components you have, do you always need the one you don't have!
But there are some that can be used in designing the circuit, just to see if it may work, before investing in the specific components, targeted to the project.
I am wondering if these component boxes / bags you can buy, if they will be a good start?
But there are some that can be used in designing the circuit, just to see if it may work, before investing in the specific components, targeted to the project.
I am wondering if these component boxes / bags you can buy, if they will be a good start?
It's surprising what you can build with a few generic parts.
Resistor assortment packs are always worth getting but beyond that I would order individually, get 5 or 10 each of small caps and the same for common transistors.
Don't go for exotic high spec caps, get general purpose ones as they are only used for prototyping and experimenting and can be very much cheaper.
Resistor assortment packs are always worth getting but beyond that I would order individually, get 5 or 10 each of small caps and the same for common transistors.
Don't go for exotic high spec caps, get general purpose ones as they are only used for prototyping and experimenting and can be very much cheaper.