Introduction
In this project, I am going to modify a Build Your Own Clone "Confidence Booster" electronic kit and turn it into a fully functional guitar pedal which I am calling the "Super Boost".
Plan
The B.Y.O.C. "Confidence Booster" kit is an excellent linear boost circuit. I have built one previously, and I was impressed by the quality design and ease of build. However, once built it is not particularly useful as it lacks several elements that would be required in order to incorporate it in a music rig or guitar setup. For this reason, I've decided to modify the circuit to accept external power, have a "true" bypass switch, a user-controlled gain level, an LED power indicator light, and to put the entire circuit in a useful case.
Parts List
For this project, I have used the following components.
1 - B.Y.O.C. "Confidence Booster" kit and all parts that went with it.
1 - Hammond 1590B enclosure (A solid case to put everything in.)
1 - A100k potentiometer (To replace the trim pot the kit came with.)
1 - 5v LED (For power indication.)
1 - LED bezel (To protect the LED physically.)
1 - 220 Ohm - 1kOhm resistor (To protect the LED from current overload.)
1 - 2.1mm DC switching power adapter receptacle (To provide external 9v DC power.)
1 - 3PDT "true bypass" foot switch (To enable/disable the pedal.)
2 - Waldom Nylon Lock Nuts 4-40 size
2 - Waldom Nylon Screws 4-40 1/4 inch size (These are to provide a plastic buffer between the circuit and the case. Hot glue would have probably worked just as well, but been more permanent.)
Connector wire (No larger than 22 gauge.)
1 - 8-pin socket (for the timing chip, I don't like soldering chips directly to the board)
1 - 9v Battery snap (optional) (The kit came with a faux leather snap, but I liked the hard plastic one better.)
1 - mono 1/4th receptacle jack (optional) (The kit came with a stereo jack, but the mono jack takes up slightly less room in the case.)
1 - Philmore Knob 0.8" Dia/0.67" High Part 3015 (A knob for the potentiometer)
Design
The circuit allows for input and output audio sleeve ground to connect to the board. I am adding the grounds for the other components to the 9v DC power adapter ground.
Adding the potentiometer is simple; the taper pot and the trimpot both have the same connectors, and all that needed to be done was install some wire leads from the board to the pins on the potentiometer.
Adding the LED, DC power adapter, and 3PDT switch was a little more complicated. I worked out the following schematics for wiring the switch and DC power adapter:
Process
To start the build, I followed the instructions from the B.Y.O.C. website. The instructions are really well written, and were easy to follow. I built the board as instructed, but I soldered the 8-pin socket to the board instead of the provided chip to minimize potential heat damage to the chip itself. The only component I didn't solder to the board was the trimpot, as I was replacing that with the taper potentiometer later on.
I then started planning my layout in the Hammond enclosure. I wanted the components to be accessible, but there were a lot of parts to fit into a small enclosure. I used a ruler to make the placements and measure the location of my component holes. One goal of my component placement was making the 9V battery snug against the 3PDT to keep it from banging around.
In this project, I am going to modify a Build Your Own Clone "Confidence Booster" electronic kit and turn it into a fully functional guitar pedal which I am calling the "Super Boost".
Plan
The B.Y.O.C. "Confidence Booster" kit is an excellent linear boost circuit. I have built one previously, and I was impressed by the quality design and ease of build. However, once built it is not particularly useful as it lacks several elements that would be required in order to incorporate it in a music rig or guitar setup. For this reason, I've decided to modify the circuit to accept external power, have a "true" bypass switch, a user-controlled gain level, an LED power indicator light, and to put the entire circuit in a useful case.
Parts List
For this project, I have used the following components.
1 - B.Y.O.C. "Confidence Booster" kit and all parts that went with it.
1 - Hammond 1590B enclosure (A solid case to put everything in.)
1 - A100k potentiometer (To replace the trim pot the kit came with.)
1 - 5v LED (For power indication.)
1 - LED bezel (To protect the LED physically.)
1 - 220 Ohm - 1kOhm resistor (To protect the LED from current overload.)
1 - 2.1mm DC switching power adapter receptacle (To provide external 9v DC power.)
1 - 3PDT "true bypass" foot switch (To enable/disable the pedal.)
2 - Waldom Nylon Lock Nuts 4-40 size
2 - Waldom Nylon Screws 4-40 1/4 inch size (These are to provide a plastic buffer between the circuit and the case. Hot glue would have probably worked just as well, but been more permanent.)
Connector wire (No larger than 22 gauge.)
1 - 8-pin socket (for the timing chip, I don't like soldering chips directly to the board)
1 - 9v Battery snap (optional) (The kit came with a faux leather snap, but I liked the hard plastic one better.)
1 - mono 1/4th receptacle jack (optional) (The kit came with a stereo jack, but the mono jack takes up slightly less room in the case.)
1 - Philmore Knob 0.8" Dia/0.67" High Part 3015 (A knob for the potentiometer)
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| Parts included in the kit |
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| Additional parts |
Design
The circuit allows for input and output audio sleeve ground to connect to the board. I am adding the grounds for the other components to the 9v DC power adapter ground.
Adding the potentiometer is simple; the taper pot and the trimpot both have the same connectors, and all that needed to be done was install some wire leads from the board to the pins on the potentiometer.
Adding the LED, DC power adapter, and 3PDT switch was a little more complicated. I worked out the following schematics for wiring the switch and DC power adapter:
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Process
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| Always test your resistors before use. |
To start the build, I followed the instructions from the B.Y.O.C. website. The instructions are really well written, and were easy to follow. I built the board as instructed, but I soldered the 8-pin socket to the board instead of the provided chip to minimize potential heat damage to the chip itself. The only component I didn't solder to the board was the trimpot, as I was replacing that with the taper potentiometer later on.
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| An organized board is easier to troubleshoot. |
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| Checking my soldering work. |
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| Laying out the parts. |
I then started planning my layout in the Hammond enclosure. I wanted the components to be accessible, but there were a lot of parts to fit into a small enclosure. I used a ruler to make the placements and measure the location of my component holes. One goal of my component placement was making the 9V battery snug against the 3PDT to keep it from banging around.
After carefully drilling out the holes, I used sandpaper to smooth out the edges before applying some paint. Spray painting took several days as I did 6 very light coats, 3 with a primer, and 3 with a metallic blue.
While the parts were drying I started wiring the various components together.
An extremely annoying design flaw in the 2.1 mm DC receptacle is that the lug nut for attaching it to the case in on the inside. That means I have to place the receptacle first before placing the lug nut or soldering final connections to the board.
Engineering / Mathematical Calculations
By splitting the current at the 9V supply to feed the circuit board and the LED separately, I am creating a parallel circuit. In parallel circuits, voltages remain the same, so I am feeding the LED the same 9V as the circuit board. In parallel circuits, the addition of all of the currents is the same as the current being supplied by the power source. By putting a resistor in-line with the LED, i will be restricting the current used in that side of the parallel circuit, thereby saving most of the current for the circuit board.
To calculate the necessary resistor, I will use Ampere's law. V = IR.
The supplied voltage in this circuit is 9V, but the LED is capable of handling up to 5V. The total voltage the resistor must deal with is therefore 4V. The maximum current the LED is capable of handling is 20mA, or 0.02A. Dividing 4V by 0.02A, we get a resistance of 200 Ohms. This is the minimum resistance necessary to keep from burning out the LED. However, I don't want to drive the LED at it's brightest level, so I will use a 1k Ohm resistor to keep the LED at a level of light that I prefer. This will drive the LED at about 4mA.
Evaluation
This was a fun project to do, and I am happy with the outcome. The main difficulty I encountered was fitting the components in the box. If I repeat this project I think I will either shuffle some of the components around (especially the battery) or just start with a larger project box. Thanks for reading.
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| Measured location of holes. |
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| Sketch of the component layout. |
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| Holes drilled and spray painted. |
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| Finished paint. |
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| Power harness assembly. |
While the parts were drying I started wiring the various components together.
An extremely annoying design flaw in the 2.1 mm DC receptacle is that the lug nut for attaching it to the case in on the inside. That means I have to place the receptacle first before placing the lug nut or soldering final connections to the board.
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| 3PDT switch assembly. |
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| A snug fit, but all components are isolated. |
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| All components soldered. |
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| A very snug fit. |
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| Finished top view. |
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| Finished front view. |
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| Checking to see if the LED works. |
Engineering / Mathematical Calculations
By splitting the current at the 9V supply to feed the circuit board and the LED separately, I am creating a parallel circuit. In parallel circuits, voltages remain the same, so I am feeding the LED the same 9V as the circuit board. In parallel circuits, the addition of all of the currents is the same as the current being supplied by the power source. By putting a resistor in-line with the LED, i will be restricting the current used in that side of the parallel circuit, thereby saving most of the current for the circuit board.
To calculate the necessary resistor, I will use Ampere's law. V = IR.
The supplied voltage in this circuit is 9V, but the LED is capable of handling up to 5V. The total voltage the resistor must deal with is therefore 4V. The maximum current the LED is capable of handling is 20mA, or 0.02A. Dividing 4V by 0.02A, we get a resistance of 200 Ohms. This is the minimum resistance necessary to keep from burning out the LED. However, I don't want to drive the LED at it's brightest level, so I will use a 1k Ohm resistor to keep the LED at a level of light that I prefer. This will drive the LED at about 4mA.
Evaluation
This was a fun project to do, and I am happy with the outcome. The main difficulty I encountered was fitting the components in the box. If I repeat this project I think I will either shuffle some of the components around (especially the battery) or just start with a larger project box. Thanks for reading.
Do you have a link to the parts that I would need? I'm a little confused on what to buy for some of this since i'm just starting to do this. I already build a confidence booster and would love to turn it into a pedal like you did.
ReplyDeleteYou could probably find most of them on Amazon, that's what I originally did. For example: https://amzn.to/2wrplKp
DeleteIn the states there are probably better places though, such as Smallbear (http://smallbear-electronics.mybigcommerce.com/) or Mammoth (https://www.mammothelectronics.com/).
Hope that helps!