DIY Axe-Fx Foot Controller for $50 (Open Project)

[Rex]

There is no way to tell from the pictures whether it is connected well. From what I can see, the solder joints appear to have been heated well enough for the solder to flow properly. If the connections feel solid, and they are not touching each other, I would expect it to work.

 

[tysonlt]

I would avoid dropping a blob of solder onto the joint. The goal is to get a molten pool of solder around the joint so that when it cools it creates a solid piece with no air inside it. Dropping a blob might create bubbles and 'dry' areas which can lead to very subtle problems down the track.

Your iron tip looks ok, just give it a good clean between solders by wiping it on a damp sponge or cloth. Then put a bit of solder on it so that you get a nice shiny layer of solder on the tip - not too much. If the iron is hot enough the solder should just flow onto it easily. Then hold the iron under the wire (use a clamp or even a peg to hold the wire) so that the wire heats up, and feed a bit of solder onto it. Again it should just flow, it only takes about a second. You will then have a nice shiny solder layer on the end of the wire. Make sure it is shiny and not dull. This is called 'tinning' the wire.

Then you want to do the same for the terminal on the plug. You only need a little bit of solder to create a layer on the surface of the terminal, not so much that it covers over the hole.

Once there is solder on the wire and on the terminal, you are ready to solder them together. The aim now is just to melt the solder that's already on both parts, this will help to make a nice solid connection. Feed the tinned wire through the hole in the tinned terminal - I like to bend the tinned wire slightly so it creates a kind of hook. Now wipe the soldering iron tip clean, tin it again (add another layer of solder on the tip), and hold it under the terminal. It should start to melt the solder together in about a second. Feed a little bit of extra solder on while you're doing this, but not too much - you might not even need any!

The trick I found learning to solder was that once you have heated the solder, let it melt without adding heaps more solder. It shouldn't really create a big ball. Once it's melted, you will see it form like a shiny little pool. I'm not an professional, but this is how I learned to do it!

 

[tysonlt]

Your existing solders look ok but might have a few dry areas. One thing you can do is just tin the soldering iron and heat them up again. All you need is for the solder to flow around into all the gaps, only takes a second.

Otherwise - they might be fine!

 

[RoketRdr]

I would avoid dropping a blob of solder onto the joint. The goal is to get a molten pool of solder around the joint so that when it cools it creates a solid piece with no air inside it. Dropping a blob might create bubbles and 'dry' areas which can lead to very subtle problems down the track.

Your iron tip looks ok, just give it a good clean between solders by wiping it on a damp sponge or cloth. Then put a bit of solder on it so that you get a nice shiny layer of solder on the tip - not too much. If the iron is hot enough the solder should just flow onto it easily. Then hold the iron under the wire (use a clamp or even a peg to hold the wire) so that the wire heats up, and feed a bit of solder onto it. Again it should just flow, it only takes about a second. You will then have a nice shiny solder layer on the end of the wire. Make sure it is shiny and not dull. This is called 'tinning' the wire.

Then you want to do the same for the terminal on the plug. You only need a little bit of solder to create a layer on the surface of the terminal, not so much that it covers over the hole.

Once there is solder on the wire and on the terminal, you are ready to solder them together. The aim now is just to melt the solder that's already on both parts, this will help to make a nice solid connection. Feed the tinned wire through the hole in the tinned terminal - I like to bend the tinned wire slightly so it creates a kind of hook. Now wipe the soldering iron tip clean, tin it again (add another layer of solder on the tip), and hold it under the terminal. It should start to melt the solder together in about a second. Feed a little bit of extra solder on while you're doing this, but not too much - you might not even need any!

The trick I found learning to solder was that once you have heated the solder, let it melt without adding heaps more solder. It shouldn't really create a big ball. Once it's melted, you will see it form like a shiny little pool. I'm not an professional, but this is how I learned to do it!

Your existing solders look ok but might have a few dry areas. One thing you can do is just tin the soldering iron and heat them up again. All you need is for the solder to flow around into all the gaps, only takes a second.

Otherwise - they might be fine!

What he said. Not to mention you can easily get a cold solder joint which wont last and will eventually fail causing shorts to the other connections.

 

[Piing]

Just an old pic of the prototype

New builders, no messy pics to share?

 

[Anese]

Thanks to you again guys, even though i think the first attempt will make things work, but i decided to make it again.
I redid the three terminals. i removed the wires by heating the solder joints and soldered them again.
my new attempt is much better and healthier. "still not looking perfect" but i would say it can be accepted.

Now what i want to know is how to connect the 15 terminals of each stomp switch to ground.
so each switch will have one terminal to be connected to one of (22,24,26....etc) pins,
but for ground connection there's 4 ground pins in the Arduino, (2 ground pins in the digital outputs/inputs section) and (2 ground pins in the power pins section)
which ground pins of the Arduino board should I connected the 15 switches to and how?
I have 15 terminals need to be grounded and I only have 4 ground pins in the Arduino !!
pardon my ignorance

Thanks again

 

[iaresee]

I have 15 terminals need to be grounded and I only have 4 ground pins in the Arduino !!

Bunch them up. All grounds are equal, so you can put multiple wires on a single pin or spread them out across several ground pins in groups. You can even run a wire from terminal to terminal and then from the final terminal go to a ground pin on the Arduino. If you look at the top of @Piing's picture above, that's exactly what he did with the white wire that goes from switch to switch. It's a daisy chain to ground. He even tied ground on the LEDs by the switches to that run it looks like.

Use a consistent colour wire for ground to make your life easier when you troubleshoot.

Regarding our solder picture, double check you didn't short anything out there? Use a continuity checker on your multimeter to test that there's no connection between each pin. Touch a probe to one pin and then the other probe to another pin -- if it beeps, you've got a short. Repeat test for all combinations of pins. It's hard to tell from your picture, but I'd definitely check that for shorts before I connected it to my Arduino.

 

[Piing]

Now what i want to know is how to connect the 15 terminals of each stomp switch to ground.
so each switch will have one terminal to be connected to one of (22,24,26....etc) pins,
but for ground connection there's 4 ground pins in the Arduino, (2 ground pins in the digital outputs/inputs section) and (2 ground pins in the power pins section)
which ground pins of the Arduino board should I connected the 15 switches to and how?
I have 15 terminals need to be grounded and I only have 4 ground pins in the Arduino !!

You don't need to wire the ground terminal of each switch and led individually to the board. Join them all in a daisy chain with a single wire, like I'm highlighting in yellow color at this pic:

 

[Anese]

Bunch them up. All grounds are equal, so you can put multiple wires on a single pin or spread them out across several ground pins in groups. You can even run a wire from terminal to terminal and then from the final terminal go to a ground pin on the Arduino. If you look at the top of @Piing's picture above, that's exactly what he did with the white wire that goes from switch to switch. It's a daisy chain to ground. He even tied ground on the LEDs by the switches to that run it looks like.

Use a consistent colour wire for ground to make your life easier when you troubleshoot.

Regarding our solder picture, double check you didn't short anything out there? Use a continuity checker on your multimeter to test that there's no connection between each pin. Touch a probe to one pin and then the other probe to another pin -- if it beeps, you've got a short. Repeat test for all combinations of pins. It's hard to tell from your picture, but I'd definitely check that for shorts before I connected it to my Arduino.

I still don't really get the ground connection. but ill just wait for some other replies. (thanks though, i really appreciate it)
For checking if there's any shorts between the midi pins i can assure you that there aint any excess solder between the pins and no pins are touching, but i'll try to borrow a multimeter and do check for shorts the way you suggested.

 

[iaresee]

I still don't really get the ground connection. but ill just wait for some other replies. (thanks though, i really appreciate it)

Does this help?



The green wires are the common ground wires. With only one ground terminal, you can daisy chain them like this and then run the final one in the chain the ground terminal. Red wires are the hot wires heading to the hot terminals on the Arduino header.

For checking if there's any shorts between the midi pins i can assure you that there aint any excess solder between the pins and no pins are touching, but i'll try to borrow a multimeter and do check for shorts the way you suggested.

Checking for shorts now saves you heartache later.

 

[Anese]

You don't need to wire the ground terminal of each switch and led individually to the board. Join them all in a daisy chain with a single wire, like I'm highlighting in yellow color at this pic:
View attachment 71254

At switch No.2 where i marked it with a red circle, there are 3 wires one coming from Switch No.1 terminal, another wire coming from LED and finally a wire going to Switch No.3, (those 3 wire ends are twisted together and and soldered to switch No.2 terminal.
IS THAT CORRECT SIR?

 

[Anese]

Does this help?

View attachment 71255

The green wires are the common ground wires. With only one ground terminal, you can daisy chain them like this and then run the final one in the chain the ground terminal. Red wires are the hot wires heading to the hot terminals on the Arduino header.


Checking for shorts now saves you heartache later.

Yes it's clear
Thanks, and Yes I will do check for shorts as your command before i do anything else.

 

[iaresee]

At switch No.2 where i marked it with a red circle, there are 3 wires one coming from Switch No.1 terminal, another wire coming from LED and finally a wire going to Switch No.3, (those 3 wire ends are twisted together and and soldered to switch No.2 terminal.
IS THAT CORRECT SIR?

Yes, they're all soldered to the same junction point. That's a ground point, part of the daisy chain of ground wire that runs to the ground terminal on the Arduino.

 

[RoketRdr]

Anese...what iaresee,Piing, tysonlt and Rex stated in the previous 10 posts are very critical. I will +1 them times 1000. I HIGHLY HIGHLY suggest you get an Ohm meter and test your connections and measure the resistance of not only each joint but each circuit. That will give you an idea of how good your solder joints are under standard operations. When you push the current in the circuits under extremes it will reveal very quickly if you have cold solder joints or bad joints. A temp prob or gun will really help as well.

 

[iaresee]

When you push the current in the circuits under extremes it will reveal very quickly if you have cold solder joints or bad joints.

This is all low voltage, low draw electronics so I don't think he's at risk of anything more than frying his Arduino board's processor. It's just easier to check it all as you're assembling than to put it all together and find out you have a problem and have to check it all then.

 

[Piing]

Exactly. There is nothing like a thoughtful visual inspection for both correct assembly and soldering

https://learn.adafruit.com/adafruit-guide-excellent-soldering/common-problems

 

[Reaper]

With grounding make sure not to create a ground loop by connecting the end of the ground wire to the beginning. Ground loops are antenna's which receive / introduce noise in your system. Even in a non sonic signal chain this is unwanted. So create one central ground point where all ground wires converge like rays of a star.

 

[Anese]

Hello everyone again
before i starte soldering the whole thing together i thought i'd just mount everything in place and see if it fit properly.
and seems everything is in the right place. (ignore those red switches i'll just swap them when i get more stomp switches).
I have a question though, is it ok if i just solder the resistors straight to the LED leg, and also do the same with the Switch terminal? instead of soldering the resistor end to a wire then solder the wire to the terminal ?
i saw a guy on youtube doing it this way. so I figured i'd just ask before i do it (screenshot attached) of course i will cut the legs shorter.
also is it ok if use 0.7 mm wire for the ground daisy chain (it's easier to handle) ? and at the end of the ground daisy chain I will solder 0.5 jumper wire and hook it to the ground terminal in the arduino board.
for the rest of the connections i will be using 0.5 mm jumper wires.
Thanks

 

[RoketRdr]

Hello everyone again
before i starte soldering the whole thing together i thought i'd just mount everything in place and see if it fit properly.
and seems everything is in the right place. (ignore those red switches i'll just swap them when i get more stomp switches).
I have a question though, is it ok if i just solder the resistors straight to the LED leg, and also do the same with the Switch terminal? instead of soldering the resistor end to a wire then solder the wire to the terminal ?
i saw a guy on youtube doing it this way. so I figured i'd just ask before i do it (screenshot attached) of course i will cut the legs shorter.
also is it ok if use 0.7 mm wire for the ground daisy chain (it's easier to handle) ? and at the end of the ground daisy chain I will solder 0.5 jumper wire and hook it to the ground terminal in the arduino board.
for the rest of the connections i will be using 0.5 mm jumper wires.
Thanks

Yes you but keep in mind that if a resistor goes bad you’ll have to desolder the LED or switch to replace it which can weaken or damage them.

 

[Rex]

I have a question though, is it ok if i just solder the resistors straight to the LED leg, and also do the same with the Switch terminal? instead of soldering the resistor end to a wire then solder the wire to the terminal ?
i saw a guy on youtube doing it this way. so I figured i'd just ask before i do it (screenshot attached) of course i will cut the legs shorter.

There are two potential issues with that.

1) LED legs and resister legs are stiff. Unlike stranded hookup wire, they’re not flexible. There will be long-term physical strain on the components, and that could lead to early failure.

2) You will have long runs of uninsulated wire. This poses the risk of things touching each other when they really shouldn’t be touching each other.