| ELECTRONICS HOW TOHow I Created my own Pedals |
|
This is kind of an expansion on the "guitar" electronics tutorial. This area discusses more about effects pedals, i.e. "Stompboxes" as a lot of people call them, and how they work. As well as my methods of development and how I tend to teach myself something new every freakin' time.
I want to make it clear I'm not an electronics expert, nor do I ever claim to be. This is more like a "Cliffs Notes" and "write as I go" thing on this website. What you do is your responsbility, not mine. I'm not responsible for burned up IC's, or failure to follow basic Electronics. If you want to know more, DIY Stompbox has a good bit of information on this. Anyway, consider this more of a "cliffs notes" of my journey into the world of electronics beyond pickups, switches, pots, and capacitors.Switching - The Easy Stuff Switches, if you read the guitar electronics tutorial, are basically a set of changable contacts inside a box. You push the button or move the lever, and the contacts change position, changing the status of the lever. If that does not explain much, let's start by talking about how electronics parts suppliers talk about switches, using the terms "Pole" and "Throw". A Pole in switch nomenclature, refers to how many "Rows" of contacts. A Throw on the other hand, is how many positions the lever/button can change state to. So a SPST Switch would be "Single Pole, Single Throw", and a DPDT switch a "Double Pole, Double Throw". In Pedals, the most common switches we use for switching an effect on and off is "3PDT" - ie "3 Pole, Double Throw". An eay way to think about it is like a Excel spreadsheet - the "Rows" are the poles, the Columns are the "throws" of the switch. These switches also come in "Momentary" varieties, which may be useful if your effect has settings or is intended to be used for a more musically punctated way - ie, a "Hold" feature on a custom Delay Pedal, or the "Space Invaders Crash" effect on my Fazz Fuzz pedal. The Simplest Switch you may encounter building a "Stomp" device would be the "Footswitch" for your amplifier. For a time, at least in the 1980's, Amplifier Footswitches could be pretty basic, it was just a SPST switch (2 contacts) wired to a regular, mono, 1/8" cable. This was used on other amplifiers, but this is how my Epiphone SC28 worked for changing channels and turning the Chorus and Reverb on and off. More sophisticated footswitches called an A/B switcher, can be used to connect to two amplifiers and switch between them. This is how a lot of big time bands used to switch between 2 amps for clean and dirty - say you have a Fender Twin Reverb on "A" and a Marshall JCM800 on "B". This also can be used to bypass a bank of effects pedals and go straight to the amplifier. All the switch does is changes the hot-lead between 2 other jacks, allowing for 2 inputs, or 2 outputs, depending on your purpose. But the most common circuit I use in my effects is pretty standard. It uses a 3P2T stompbox footswitch - which acts as both a on/off switch for the status LED and as a bypass switch for the effects board inside the effect. You can kind of look at pedals this way, they are like modular boards you ucould plug into an input and output side of this switch setup, and then use this footswitch to bypass the effect. A lot of people call this true bypass - but a TRUE BYPASS effect would truly need a 4P2T switch, which are more expensive and harder to get. But hey exist. What those would do is add extra lines for the ground, sacrificing the LED Functionality, but disconnecting it from both sides. Some effects achieve this using a a momentary push button and a Switching IC instead. Basically, the whole goal of making a footswitch in this method, is to have a easy, simplified, and modular way of building effects pedals so I don't need to redesign a whole new switching circuit every darned time. This also allows me to build a custom breadboard setup for making/testing homebrew effects. Which right now I'm currently building such a box.Power Source Let's talk about power sources. The De-facto standard pedal power source is the Center Negative Barrel Jack at 9vDC (9 Volts Direct Current), where power is sourced from the negative line, and fed through to the positive line - ie power flows negative to positive. Usually this current rating is around 500mA to 1A of current draw. One of the trickiest things for me when I started dabbling in Pedals in 2017 was inverting my train of throught - because prior to this, I had been thinking only about the audio flow on the + side of the equation, as I had been wwiring guitars, and pretty much anything not having to do with altering the output of the guitar, save for phase reversals or volume and tone controls, fed off of the positive side of the equation. Another, less-as-standard connector type I've used is 1/8" mono with a positive tip, my SkullFuzz pedal uses that. That was the style used by DOD's pedals. So starting out, I stuck to the 9VDC specification. Though I used Center Positive first. Bazz Fuss - Simple Fuzz Circuit Probably the easiest pedals to start making are fuzz pedals. AT their most basic, such as the Bazz Fuss circuit I'm using here, they have one Darlington transistor, a clipping diode (or two), an input capacitor, usually a bigger electrolytic cap, and an output capacitor, usually a ceramic disc or microfilm one, and a resistor at the end to balance the output. Admittedly, I learned this circuit from an Aussie or New Zealander dude on YouTube as the "7 Minute Fuzz" - this is what gott me started. The Bass Fuzz basically gives you a nice, solid, basic, good sounding circuit to start from, and build off of to experiment with your own fuzz design. Reverb Circuits - Using a Belton Brick The Belton Brick is a "reverb module" of sorts. It utilizes a series of ICs inside (PT2399s to be exact - which are Reverb chips used in a lot of cheap amps and Karaoke machines) to make it basically a Reverb on a chip. It comes in several varieties. CMOS Chips & Guitar Synthesizers A good place to learn the basics on these is Parasit Studios. Basically, the guy there is all about making guitar synthesizers based on various CMOS 40xx series chips (which are also great for other effects). |