build your own “business card” boost pedal
Congratulations on your interest in building your own effects pedal! Rare Buzz Effects business cards are designed to be built into simple boost pedals and are a great way to get your feet wet in the world of pedal construction. Some basic soldering skills are required, but the parts count is low and assembly should be simple. The first step is to decide which version of the pedal you would like to build:
- Cranberry Boost: this simple boost is the final gain stage of the Cranberry Drive and is very similar to other transistor-based boost designs, such as the LPB-1. To get even more gain from this design, R5 can be reduced to any value between 100 and 1K ohms.
- “Fetzer” Boost: this boost uses the “fetzer” valve scheme. This has a warmer, more tube-like sound than the Cranberry Boost.
Next, make sure you have the components you need to complete the pedal construction. This design uses TO-92 transistors, any film capacitor with a 5mm (0.2″) lead spacing, and standard 1/4W resistors. Substitutions can of course be made, but the components may not line up as nicely on the board. See the image below for a complete bill of materials for the pedal:
A few notes about the components: First, please note that the potentiometer should be the long leg style – this will line the potentiometer up with the stomp switch on the enclosure. These are a little trickier to find than the standard style, but Small Bear had them the last time we checked. Alternatively, you can use a lugged potentiometer which will allow you to mount it anywhere in the enclosure. The transistors I used in my design were the 2N5088 and the 2N5457, respectively. I chose these based on availability and cost, but others can certainly work – just make sure you are sourcing an NPN transistor for the Cranberry Boost or an N-channel JFET for the “Fetzer” Boost. If you substitute transistors, double check the pin configuration because these can vary from part to part. Finally, the first run of business cards did not have a location for LEDR – you will need to attach this directly to the LED leg between the LED and the board. In either case, you could use a pre-wired LED (many of which have their own resistor) which allows some flexibility in where the LED is mounted. If your LED has its own current limiting resistor, mount the positive (anode) lead to the square pad on the LED image, and mount the ground (cathode) lead to the right-most pad on the LEDR image.
Use the guide on this page (click the image for a printable PDF) to mark your enclosure for drilling. The outline on this guide reflects the dimensions of the business card, so feel free to position the holes however you choose. The BC Boost is designed to be mounted either horizontally or vertically in a standard 125B enclosure. If you used a lugged potentiometer, you can mount it anywhere you’d like. If you used the PC mount style, you will need to mount it as indicated. The LED hole size will vary depending on your choice for size and bezel. Again, if you chose a pre-wired LED, this can be mounted anywhere.
If you are unsure about building your own BC Boost, I have a blog post that follows my build of the Cranberry version with pictures and descriptions. Check it out here, and feel free to reach out with any questions you might have about the circuit or the build.