Vox VISCOUNT V1154 4 Button Footswitch

[duckman]

Hello All,

I a kind of a noob with all of this. I am trying to build a footswitch for the
vintage Vox Viscount V1154. I have the schematic but it does not say what
type of LED (LAMP) is used in the 4 button footswitch or give any indication
of the values for the Distortion light. There is 30.5v on pin 5 to power the
light but I am not sure how to go about getting a light to work. Is the light
a standard LED or is there something special about it?

Does anyone know anything about or can help me with this information?

Thank you.

[R.G.]

It's not an LED. It's an incandescent lamp, 24V I think. That probably makes it 24V/20ma. Mouser has some 24V bulbs if you can find one that has the same body shape/pins/etc.

However, 20ma is enough to run an LED. You can put in an LED with a 2.2K to 4.7K resistor to replace the bulb. Don't go below 2K on the resistor; you may have to go larger to get the brightness down. And of course, you'll have to somehow adapt it to fit in there physically.

[52 Bill]

And if you want the original styles switches, the MRB switch needs to be a momentary rather than a latching type.

North Coast carries NOS lamp assemblies for the footswitches, but I'd go with the led and dropping resistor.

[duckman]

Thank you guys for chiming in.

I am building this footswitch in my own enclosure.

Which leg of the LED should go to the resistor and which should be connected
to the switch itself anode/cathode?

I did notice there is a 330 ohm resistor inside the amp inline with pin 5 on the
schematic. Will this resistor be enough or should I add another as suggested?

[R.G.]

I am building this footswitch in my own enclosure.

That'll make the mounting problem easier. Definitely go for an LED in that case.

Which leg of the LED should go to the resistor and which should be connected
to the switch itself anode/cathode?

It does not matter. The resistor can go in series with either leg of the LED. But you do have the problem of DC polarity. The switch as shown in the schemo has one end tied to ground in the pedal, and one end pulled to -30.5V. The anode end of the LED must go to the ground side, and the cathode/bar side must go to the switched -30.5V side. The resistor can be on either side of the LED in that setup.

I did notice there is a 330 ohm resistor inside the amp inline with pin 5 on the
schematic. Will this resistor be enough or should I add another as suggested?

No, you must add another resistor as suggested. I checked the schemo, figured the current that had to be running through a 330R resistor to get 24V on a bulb, and found that to be 0.02A. I checked the Mouser Electronics catalog and found that 0.02A 24V bulbs do exist, decided that must be what was used. Then I computed that advice on the resistors based on putting less than 20ma through an LED. LEDs burn out with more than 20ma (about) continuously through them, so I computed the minimum resistor (1.5K) and added a safety factor (to get to 2K) and suggested the nearest standard value (2.2K) as the first place to go. The LED will be as bright as it gets at 1.5K. That will be too bright for today's high brightness LEDs, so you may want a bigger resistor (for smaller current) to cut the brightness some.

But the 330R will burn up the LED, and probably the 330R resistor.