Multi-Purpose Booster/Buffer PC Board A DOZEN CIRCUITS WITH ONE PCB Please don't post the link to this page on any forum or web site as it is a bonus intended only for those who have purchased pc boards from AMZ. Thanks. POWER SUPPLY FILTER The circuit shown here is a power input filter that will condition the voltage supply to make it clean, stable and noise-free. You would install it between your power supply and any pedal that is sensitive to noise or hum. The power supply connects to +9v of this pcb and the circuit board output connects to the pedal's positive voltage pad. Parts List R2 - Jumper R3 - 2.2k R5 - Jumper R6 - 100k (optional) R9 - 100 ohms C1 - 22uF C3 - Jumper C4 - 100uF Q1 - NPN transistor (2N4401 or similar) All resistors are 1/4w and capacitors are in uF. Notes: The dc voltage of Out2 to ground should be about 0.65v less than V+, or about 9 - 0.65 = 8.35v If you pull a lot of current through this circuit, R9 should be a 1w or 2w rated resistor. 5v Regulator The power supply circuit can be modified to act as a 5v regulator to supply power to digital chips and circuits that need a stable source. A zener diode is used in place of R4. It does not use much current so it can be any low wattage device such as the 1N5232B. Parts List R2 - Jumper R3 - 2.2k R4 - 5.6v zener diode R5 - Jumper R6 - 100k (optional) R9 - 100 ohms C1 - 22uF C3 - Jumper C4 - 100uF Q1 - NPN transistor (2N4401 or similar) All resistors are 1/4w and capacitors are in uF. Notes: The dc voltage of Out2 to ground should be close to 5v I suggest that you use the inductor in place of R9 as detailed in the Modifications section below. 78L09 Regulator The Multi-Purpose pc board can even be used as a power supply regulator, utilizing the 78Lxx series integrated circuit in the TO-92 package. The relative pin designations for the 78Lxx on this board are: pin 1 = emitter, pin 2 = base and pin 3 = collector. Mount it with the flat side of the TO-92 facing the right side of the board like this. Parts List R4 - Jumper R5 - Jumper R6 - 1uf capacitor R9 - Jumper C3 - Jumper C4 - 0.33uF Q1 - 78L09 (or 78L05 as required) All resistors are 1/4w and capacitors are in uF. Notes:The datasheet for the 78Lxx series regulator states that it has a 1.7v dropout, which means that for proper regulation, the input voltage must be 1.7v higher than the regulated output voltage. For the 78L09, the input voltage needs to be 10.7v (9v + 1.7v). For the 78L05, the input voltage required is 6.7v (5v + 1.7v), and so on. There are four wire jumpers used for this circuit, so check carefully that they have all been installed. The input to the V+ should be a positive dc voltage. A 1uF capacitor is used in the position labeled for the R6 resistor. It can be any value from 1uF to 10uF. The C4 capacitor value is not critical either. It can be any value from 0.33uF to 100uF. MODIFICATIONS Use an inductor in the place of R9. A good value is 330uH, rated for at least 100ma. Mouser carries one under their part number 434-22-331. MORE CIRCUITS NPN Silicon Boosters & Buffers PNP Germanium Boosters & Buffers Jfet Boosters & Buffers Mosfet Boosters & Buffers