you can use whatever you can get. This isn't an audio signal, so it doesn't matter really.
rule of thumb says don't use ceramics in the audio path. I think it's not really about noise, but about different sound. And that's just personal taste. An alternative would be polyesther caps, i think that's what inactiveX used.

Thanks. One more thing: I don't see teh polarity on the capacitors explained on the diagram. How should I wire them?

ceramics and polys are usually not polarized, so don't worry.

maybe i'll get around to making a stripboard layout this weekend, but don't count on it. Have this planned for wayy too long yikes

I am half way done with my mod. Waiting on the capacitors to arrive.
If this works, I'll post all relevant pics in here, as well as a diagram with the vero board setup I am using.
I have wasted some space, but it should be fine.

Last edited by akira^8GB (April 19, 2013 2:40 pm)

OK I made it! Nothing blew up, the pots are working.

Last edited by akira^8GB (April 19, 2013 2:40 pm)

Ugh, talking to myself then...
After going through the whole process of making this circuit, I think: wouldn't it be almost the same to just get potentiometers of different value?
470K makes it so I traveled the whole range at half of a turn. Wouldn't 250K pots yield a much better result making the trimmers pointless?

If anybody can explain to me exactly which part of this all is the tapering circuit, I could try to make the same effect using those components and 250K pots and see where that goes...

Maybe the other pots are logarithmic audio pots? They are designed for audio applications so have a graduated curve on higher settings. I think you want a  Linear potentiometer /me barely knows what he is talking about.

The pots used to do this are linear, so the tapering is not because of that, unless the added trimmers are logarithmic and then tapering is introduced. If that's the case, then the circuit makes more problems than solutions and it's way too complicated (for me) for what it supposedly does.

i'd like to know if anybody has tried with 250K pots because it seems 470K is a ridiculous value.

It's a shame InactiveX  isn't posting here or replying my messages, he'd be able to clear my doubts right away hmm

Last edited by akira^8GB (April 18, 2013 4:42 pm)

wish i could help.. then again if i could, id have probably built it myself!
cant wait to tweak MSSIAH without having to hook up massive midi controllers! big_smile

Domu wrote:

cant wait to tweak MSSIAH without having to hook up massive midi controllers! big_smile

Are you sending anything over? ;D I could use you as a guinea pig for 250K pots... tongue

Like what?

Use away!

i tried this when I first saw it on the mssiah forum. works a treat!

Timbob wrote:

If i wanted to make this circuit easy to turn on and off while being internally build (so i can also use other joysticks)
Which connections should I disconnect? all four?

InactiveX wrote:

OK. A simple SPST switch to break either line 7 or 8 should do the job then.

Is it really that easy? Why does this site use such a complicated switch then?:

That's 4PDT right? And their schematic also doesn't account for the other 2 pots, if you're using 2 per port (4 total).

I installed 4 internal pots in my C64C a few years ago and miraculously they seem to work smoothly although they don't use the full rotation (haven't tried InactiveX's new method). However, I did something wrong when I added the switch that supposedly disables them! Now my mouse won't work. The pots still do when I have the switch set to turn them on. The way I currently have it wired, my switch redirects 5v and GND on all 4 pots, as well as X and Y on Port 2. So why is my mouse buggy?

I spent today trying to figure out the mess of wires I soldered a few years ago. Would be great if someone could answer my questions above. Thanks!

Switching 5 and 9 (the analog inputs) should be enough. You don't really need to put a switch on 7 and 8 (+5V and ground). Using a 4PDT switch is way overkill.

Now, there are different degrees of cheapness you could aim for. Here are a couple of modified schematics with descriptions. I've marked +5V with red and ground with black for clarity.

Terribly cheap: Two SPST switches. Connect 5 and 9 right through to the other jack, and connect the potentiometers in parallel through individual SPST switches. Now both switches must be in the on position for the respective potentiometer to work, and both switches must be off in order for the second jack to work properly.

Still terribly cheap: Two SPDT switches. Each input is now properly switched between the potentiometer and the second jack, but you still have two switches you need to care about.

Somewhat less cheap: One DPST switch. Same as the first example, but with only one switch to care about.

Recommended: One DPDT switches. Both lines are properly switched with a single stroke.

Last edited by nitro2k01 (June 13, 2013 10:39 am)

Wow, thanks a lot!

I'll do the last option, but instead of a DPDT per port, I'll use the 4PDT I already have to switch all 4 pots on/off at once. One less hole to drill in the case I just spraypainted.

Last edited by Awol (June 13, 2013 7:03 pm)

This is my idiot-proof schematic, for people that have no idea of electronics (like me) and want to build two pots with disable switch for port 2 potentiometers:

Just connect things together this way and you are good to go.
The components I used are the ones described by InactiveX in the first post of the thread.
The way I do the switch is by connecting the power lines of the pots of the same port together then onto the +5 lne, so all I have is to connect that line to a single switch. You don't need a DPDT switch. No power, no pot. Mouse works fine. I wouldn't like to power the mouse and the pots at the same time on the same pot, sounds prone to disaster.

As a side note, I wouldn't do almost ANYTHING that Alpha recommends.

I have to say I built this and really didn't think it was necessary to bother. I think different rate potentiometers might yield similar results.

Last edited by akira^8GB (June 13, 2013 9:42 pm)