Intro: Install LEDs in Your Amp's Footswitch
(Versión en Español aquí)
If you have a guitar or bass amplifier, the footswitch is a must-have addition that gives you the freedom to change channels and/or activate the effects loop without lifting your hands from the strings to push a button in your amplifier's control panel. However, most footswitches are just that. With this Instructable you will learn how to add a LED that lights up when you press the switch, giving a clear indication of when you have activated the circuit.
Step 1: Tools & Materials
A center punch tool.
A drill bit the same size of the LED you have selected.
Small gauge electrical wire.
Small round file.
Small straight file.
One LED for every switch you want to upgrade.
One 100k resistor for every LED.
One 9V battery.
One 9V battery clip.
One rubber band or two-sided adhesive tape.
One on/off switch.
A drop of oil.
A little woody stick.
Some old newspaper.
Step 2: Buying the LEDs
There are lots of LEDs, in lots of sizes and colors. I recommend smaller round ones because it's more simple and they do the work. In this Instructable I used 3/16" round LEDs because the on/off switch I had is that size, so all holes are the same size.
When you buy your LEDs, buy two of every color you want, because if you damage one you'll have a replacement handy. I always do that. Plus, LEDs are not expensive. On the other hand, you have to buy a good quality drill bit, because most footswitch cases are made out of very tough steel.
When choosing your drill bit, have you LED on hand to buy the right one. If you make a bigger hole, you'll have to find a way to hold it in place, and if it's too small, you'll have to go out and find the right drill bit. So, be a good ecologist and buy the right stuff the first time. Less trips to the store = less pollution.
Step 3: Disassembly.
Most footswitches have rear-mounted screws. Extract them to open the case and remove the switches. Save all the electric components in a plastic bag to protect them from metal dust.
Inspect the switches installed. To install the LEDs you'll need a 6-pin switch. If yours is a 3-pin, you'll have to go out and buy a DPST 6-pin switch as the one shown in the photo.
Step 4: Drilling the Holes.
First, get some newspaper to use below your work sufarce. This way the metal dust won't marr your table, and once you are finished there will be less cleaning to do.
Use the masking tape to mark the places where you want to drill. For this Instructable I did three holes: one for the on/off switch and one for each LED. I put the on/off switch on the back of the case to keep safe it from accidental operation.
Remember that the on/off toggle switch should be installed on the back of the case to avoid it to be moved by your foot. Put the center punch in the drilling marks and use a precise blow with the hammer to make a dent in the metal. This will be the place where your drill bit will start working; failure to do this will make your drill bit to wander around and damage the finish of your case.
Support your footswitch tightly to avoid any movement while drilling (I used a press). Put a small piece of wood below the place you want to drill, to protect your workbench in the event the bit goes through the metal too fast as it usually do.
Install the drill bit firmly in its chuck. Put a drop of oil (any oil will do) and set your drill in a slow speed. If you use high speeds, the bit won't cut and probably will break. So, you'll need to use low speed and a firm hand.
Step 5: Clean the Holes.
Once your drilling has been completed, you'll find lots of burrs still adhered to the case. I used a Dremel emery bit to cut them and clean the holes. This is not only an aesthetic issue: drilling leaves sharp edges than can hurt your fingers. If you don't have a rotary tool, a small straight file will take care of the burrs. Next, you'll have to perform the same task inside the holes with a round file. The idea is to leave a clean, smooth hole to avoid scratching the LEDs.
Once these steps have been completed, it's a good idea to apply some kind of finish to the holes, because the exposed metal can corrode. I used a touch of clear nail polish: it's cheap, easy to apply and does the work.
Now it's a good time to clean up your workbench. The following electric procedures will be safer to do with a clean enviroment.
Step 6: Prepare the Circuit.
Ok, now it's time for some electric fun. This circuit does not interfere with the amplifier's one, so it needs its own power source and on/off switch. Otherwise, the LEDs could be activated any time (like when being in your gigbag) and drain the battery.
First, study your pedal and write down which terminals are connected when its switch is on and off. The LED circuit should be connected in such a way so it lights up when the footswitch is depressed.
The SPDT switch recommended has two rows of three connecting pins. Make sure both rows are not connected in any way: your amp's control signal could be rerouted away to its circuit, disabling it completely.
Solder the wires following the diagram. It's best to attach everything prior to the installation so you can test if it works correctly.
Step 7: Test the Circuit.
To test the circuit you will need to insert the footswitch cable into its corresponding amplifier jack. Connect your instrument to the input of the amp and turn it on. The footswitch LEDs should light up only after the switches have been depressed and the desired fucntion activated. If not, check the wiring; it's possible the wires have to be reversed in the switch connecting pins.
Step 8: Make a Bed for the LED.
I used a wooden stick to make a bed for the LEDs. This is to avoid them to be pushed into the pedal's case and to protect them from rattling. I just superglued it to the inside of the case. No rocket science here.
Step 9: Install the Circuit.
Once you have tested the circuit and made sure it's working the way you want it to, it's time to put it inside its case. Start with the switches: first the on/off mini switch, then the bigger ones. Tight them carefully making sure the wires don't touch the case or each other. I recommend using heat-shrinking wrapping or electric duct tape for this.
When it comes to battery placement, it's important to remember it's gonna be there a long time, so don't skimp in this final step. Once you have it wrapped in either electric duct tape (as I did) or foam, make sure it doesn't move around. I used a ladies' hair rubber band because a plain rubber band can leave marks inside the case or react with some of the plastics inside this case. But
Once everything is fitted and secured, test it again: we don't want surprises! When everything is OK, close the case and enjoy your new footswitch with LED indicators!
Step 10: Last Words.
The best feature of this circuit is the fact it can be easily adapted to any requirements. A guitar player friend wanted to have three LEDs: one for "effects loop on" and the others for "clean channel on" and "crunch channel on". All I did was to add a LED with its resistor to the corresponding circuit. An easier way to do this is to use a single 2-color LED, so no extra resistors or holes are needed.