cheapest source of pots, diy or salvage?

im going deep with a dj controller project and faced an old enemy. the potentiometers and their high cost (for a no budget project)

bythe way im talking about variable resistors!

well ive learned that there are some sollutions
here are my chosen:

  • salvage potentiometers from old electronic equipment like stereos and stuff (takes time, lack of standards in equipment)
  • build your own using a high resistance material and a pointer to be the variable piece. (look for paper resistor)
  • use old equipment from optical mice (optical encoders and stuff to track the rotation of an element which is locked so it cant go more than 360 turn)
  • use salvaged parts from mechanical mice(same as the one above)
    both optical and mechanical mice have the option to be interfaced directly using the ps2 protocol, or the actual used parts can be taken out)
  • use some kind of motor that gives output when it turns (reversed motor for rotation input)

thats about it.
for info on the above look here:

fast sketch on the mice usage :
http://img155.imageshack.us/img155/7006/opticalstuff.png

paper resistor:

ps2 mouse stuff:
http://www.arduino.cc/playground/ComponentLib/Ps2mouse

please reply with some advice on cheap ways to immitate the variable resistor with an arduino.
kindregards johannes

apparently there is a guy that have interfaced the optical part of an optical mouse directly: http://www.martijnthe.nl/2009/07/interfacing-an-optical-mouse-sensor-to-your-arduino/

You can get potentiometers for around 0.5 us$ probably not the best quality but it's going to be difficult to come up with anything DIY that is cheaper / better.

salvage is a pain with potentiometers, they are very often not standrad shaft diameter / layout, and often not panel mountable.

Also if you want to use them with Arduino analog in you should use 10K pots, salvaging a bunch of pots all 10K is probably going to be close to impossible.

I ordered these from China for an Audio Project.

Delivery time was 2 weeks to Germany, quality is better than i exspected and work fine with Arduino.

http://www.virtualvillage.com/pack-of-25-5k-24mm-potentiometers-001493-015.html

Greetings

apogee

Goldmine has mechanical rotary encoders for $1. Encoders have the advantage for your purpose that you can implement presets, where you can't with pots. On the other hand, they don't have a mechanical stop.

If you want to trade work for cost, you can build your own optical encoders with a shaft in some kind of bearing, a led, two photodiodes, a piece of plastic, and an inkjet printed encoder pattern. Since you want a whole bunch of them, you could make this fairly simple using holes drilled in a couple of pieces of 1/8' ply or fiberboard. Use one piece to hold the bearing and the leds, one to hold the photodiodes. Use a matrix to scan them. For the shaft, use a 1/4" steel rod. Use a dremel tool to cut a couple of grooves. Find a threaded hollow round something with a 1/4" id smooth bore and cut 1" pieces for bearings. Put a "cerclip" in the top groove, add some grease, and drop the shaft in the bearing. Another cerclip holds it in place. Use a couple of nuts to hold the "bearing" on the ply. Use the same idea to hold a piece of plastic with a 1/4" hole in place on the end of the shaft. Print the encoder pattern and spray adhesive it on to the plastic. You have to align the pattern carefully, and locate the photodiodes accurately, but you could make a whole board full of "pots" this way.

You should also look into buying them surplus: the savings can be huge.

A few of my favorite suppliers:

http://www.goldmine-elec.com/

http://www.alltronics.com/

http://www.allelectronics.com/

http://www.bgmicro.com/

thanks for all the good replies. i will look back when i have time tomorrow.

about 0.5$ pots thats hell cheap. about goldmine and the other shops: do they ship to europe and whats the price.

in europe we have shared taxes so theres no border tax between the countries only from outside to inside vice versa. so as i live in denmark im interested in a european sollution :-) thanx again for nice repps!

I would ask around sound shops that do pa type equipment, might be able to score a old mixing console as its headed to the dumpster

The goldmine seems to have stopped shipping to a lot of European contries, but you can get cheap pots many places. Including in the UK.

do you know any specific places in uk?

http://www.bitsbox.co.uk/resistors/potentiometers.html

Surely you guys have surplus electronics junk shops there, don't you?

Check the "industrial"/"ethnic" parts of your town (or the closest city); invariably that is where business/industrial/salvage/surplus shops tend to be situated.

At least, that's the way it is here in America; I would assume this to be the case for most western countries as well (I wish it wasn't, at least I wouldn't have to travel as far to get to the place I love to go to here in Phoenix: Apache Reclamation and Electronics; it is what it is, though).

:)

actually theres no such thing in denmark. mostly the state takes all the electronic garbage from the recycling stations and then you dont see it again. dont know where it ends up, maybe sold to foreign countries for reuse. in denmark we only have second hand shops and lofi flee markets. these for the most dont supply electronic parts but only whole pieces of equipment.

yeah i know of the salvage armies and stuff in th states and its a great idea. but none existent in dk (decay) right now

Yes Denmark is a very expencive place to buy electronics components, and we really don't have any surplus dealers.

Only just got an Arduino reseller very recently.

I have bought from the goldmine before, but they don't ship to denmark anymore :-(

hey mikmo i can guess ur from decay as well. do you have any favorite electronics pushers?

well right now i have to go to the expensive shop and buy some few components at overprice cause buying electronics from outside denmark feels so hard :-(

but with your good advices im having more luck in the future!!! this bitbox seems quite nice. do they ship to whole eu?

thx for reps!

actually theres no such thing in denmark. mostly the state takes all the electronic garbage from the recycling stations and then you dont see it again. dont know where it ends up, maybe sold to foreign countries for reuse. in denmark we only have second hand shops and lofi flee markets. these for the most dont supply electronic parts but only whole pieces of equipment.

yeah i know of the salvage armies and stuff in th states and its a great idea. but none existent in dk (decay) right now

Weird - I guess I could never live in Denmark, then! Scrounging is almost my life!

So - is it illegal or something to sell or collect old electronics for salvage? Why doesn't Goldmine ship there anymore? Have you tried other online places (All Electronics, Alltronics, MPJA, etc)? What's up with all that?

Is it against the law there to privately "recycle" electronics? I hope I never see that day come here to the States, that's for certain! I'd cry like a baby!

;D

Goldmine also stopped shipping to Germany. I don't know why, as they are also shipping to South Africa or Korea. Don't get me wrong, but what the heck?

its not illegal theres just a bunch of taxes on everything.
beware we have a tax pr citizen at around 30 to 40 procent income.

but what the heck?

I don't know why, either, but I think I have pretty good guess: the German government imposed some restriction, like identification of RoHS (non-)compliant parts, that was too onerous for a company picking orders out of bins that contain a random mix of stuff that includes parts made before there was even an EU to regulate Scary Materials.

I don't know why, either, but I think I have pretty good guess: the German government imposed some restriction, like identification of RoHS (non-)compliant parts, that was too onerous for a company picking orders out of bins that contain a random mix of stuff that includes parts made before there was even an EU to regulate Scary Materials.

That is a pretty good guess, but i guess not the point. I order plenty of non-Rohs stuff from ebay.de here. i got a 25pack of 4ch darlingtons for like 3$ because they are non RohS.

The point is that you aren't allowed to sell stuff MADE with non-Rohs parts or use it commercially. What i do at my home stays my thing (at least for now)