1,000 4.7K Lin Potentiometers

[Guest Quenzer]

Hi, first of all thumbs up to Thorsten for such a excellent modular midi platform. Been looking for somthing like this for years ..never could afford any of the sizeable commercial solutions.

Anyways, getting to the point; I adquired around a thousand 4.7K linear Potentiometers from a amateur radio show today for a highly agreeable price.

I bought these with the intention of using them for quite a number of midibox & analog projects.

However when i checked out the schemetics for the midibox, it came to my attention that the value used is

10K ...ahh well, lucky ..but not lucky enough :)

Would it be possable to include a hardware or firmware mod which allows for different value pots to be used as a alternative for scinarios like this ?

Thanks.

[LO]

Not needed!

I got some 1K & 5K & 10K pots in my midibox

works sweet

[Guest drummond]

That's great to know! 10k faders are hard to find in Brazil, but 4,7k are easily available!!!

[LO]

just test 1 or 2 pots first

as depending on the length of wires etc you may experience some pot jitter! (I didnt ;D)

Should be OK though

[Guest Quenzer]

DOH ! ...took a fresh look at the scemetics this morning; and realised that the rails wired to the extreeme ends of the pots arent wired to some of the sensing circuitary. ...Which wouldnt of made sense with the midibox platform being modular and all (if i had bothered to think for more than a second ;)

Instead what really is happening; is that the pots are across the power rails... & that no matter what value the pots are (providing they are lin's), they 'will' give the same voltage reference to the 4051s as per their position.

HOWEVER, the potential limiting facotors are:

I) The lower the value of the pots, the larger the power sunk by each pot. For a value of 1K, 64 pots will eat up 1.6 amps ...which is considerably more than the 0.16 amps that 64 10K should eat up. my Guess is that is the lowest value should be tryed (but best avoided).

And whilst on the subject of power sunk its a good idea to pay attention to the ammount of power sunk by each pot & see that it doesnt approach the power rating of the pot itself. ...otherwise various things may burn out quick :-) ..very difficult to do at 5 volts though :)

Also id speculate that the lower the value of the pot the greater the potential for jitter & the greater the influence of wirelength from the pots. ..so keep wires short.

II) increasing the value above 10k might (speculation) cause problems due to a increasingly negligable current flowing across the pot. so that when the pot is spun round nearest to the earthed side, that the 4051 may fail to register the value properly.

...if anyone has anything to add to this, please feel free to do so. It might be nice to 'offically' state a acceptable pot value range & state the 10k value as the reccomended default. As per another posting here, there is some difficulty getting 10k pots in some places.

Laterz.

[d2k]

I got a 100 10k liner pots of ebay for 15 EU...they are pcb mount tho, which is good for me cos that's where they're goin...;)

Have a look, think there might be a few more auctions...

Good Luck!!

[goyousalukis]

While we're on the subject, I recently hooked up an apple analog joystick that I got at a flea market for $1. It has 100k pots. I tried to fit my 10k pots, but there were too many problems so I just tried the 100k's and it seems to work fine. Does anyone know if there is a potential problem with this?

Justin

[Guest Carel]

When we are still at the subject

I’ve made a bargain deal for 5 k pots. Is it possible to use them for the midibox project?  

Does any1 have experience with this type pot value?