how to add Level/Volume

[Bullet79]

Simple question guys.... How do i add a Level/Vol on a pedal that doesnt have one..

just finish building a e-vibe, but the effect volume is quite loud...

[deadastronaut]

ive had the same problem with some builds...

i put a trim pot before the output inside it till it reaches unity...no need for more drilling etc..

i;m betting theres a better way though...

[Mark Hammer]

There will usually be a terminating resistor to ground on the output, often to simply prevent switching pops, but for other reasons as well.  Many of these can be directly replaced with a pot of the same value (e.g., 100k replaced with 100k log pot).  In some instances, the terminating resistor does not correspond to a standard pot value.  In those cases, one can use a pot plus fixed resistor.

As an example, on a Ropez/Ross phaser I have from the Tonepad layout, I replaced the 150k terminating resistor in the schematic with a 100k log pot and a 51k fixed resistor (most pots are slightly less than the stated value, so I used a resistor slightly higher) to ground from the ground lug of the pot.  So, the circuit "sees" 150k to ground, in total, on its output, but the signal can be essentially tapped at different points along that 150k.  In this instance, the volume can never be shut completely off, but then I don't want to shut it off anyway.  So as wired up, the output volume lets me dial in something a bit less than bypass level, or in my instance, a bit more.  Something for leads, and something for rhythm.

[petemoore]

 A resistor [to ground as Mark detailed, or seriesed with SP].
  There are many ways to do 'it.
  There are also ways to alter the gain in a circuit [which can have volume and other possibilities] such as bypass capacitor or resistor values, a less beaten path but quite viable and may offer disadvantages or advantages. Benefits and detracts may include headroom issues, frequency control along with 'boost/cut'.
 A resistive divider [two resistors say equal value, strung between signal path and ground with the output taken from where they meet] would 1/2 the voltage output.
 A pot is an adjustable resistive divider, the wiper touches the resistive material of the wafer and 'divides' the wafer by providing a contact point.
 The consistancy of  resistance along the length of the wafer can be altered to make one end thicker or thinner [hence less resistance where 'tapered' at the end] making special 'tapered' pots.
 The outside lugs are for connecting to the ends of the wafer [the resistance of the wafer is static, the R value between these lugs is fixed] the middle lug is the 'variable divider output', called the wiper, as you rotate the shaft, the wiper contact point moves along the wafer, dividing the distance to each end point, as well as the resistance to each end point.
 "they'' [both sides of the pot] always add to the same distance [the wafer] and resistance. Turning the knob to make 60% makes 40% on the other side, 30/70%, 1/99%.. 37.3 w 62.7%..it always adds to 100% of the wafer value [and length, the wiper moves to touch different points along the wafer length.
 Shaft point at you lugs down, turn the shaft CCW for 'down all the way', imagine the 'stop point' of shaft rotation causes the knob to stop at 0 [off], pointing at about 7:00 [on a clock], the lug which the knob would point at goes to Gnd., the other outside lug goes to Signal path...wiper is output.

[Bullet79]

wooo... before it get even much more complicated, can i change the R16 on this layout..?? (its the last 100k) 

[Mark Hammer]

Abso....lutely.

[stringsthings]

Simple question guys.... How do i add a Level/Vol on a pedal that doesnt have one..

good question .... and a very useful modification to make .... step A) march on down to your local "Potentiometers R Us" store .... ( radio shack or the equivalent ) and ( for the easyvibe ) purchase a 100k log taper pot ... sometimes classified as audio taper .... the pot has 3 lugs .... there are a few ways to do the wiring .... here's one way:


looking at the back of the pot, let's number the lugs 3, 2, and 1 .... ( lugs pointing down )

1) remove R16 from the board ... ( save it for future use ... it may be a collector's item one day !!   )
   you now have two unused pads on the board
2) solder lug 3 to the top pad on the board ( nearest C6 )
3) solder lug 1 to the bottom pad on the board
4) disconnect the green wire that R16 used to be connected to ( at the top right of the board ) and connect this wire to lug 2 ... lug 2 will now be connected to the bypass switch ....

if you have trouble finding a log/audio taper pot, you can use a linear taper pot .... it just won't give you smooth volume changes when you adjust the volume of your pedal ...

[Bullet79]

THANK YOU ALL   it work like a charm....