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Schematic for single button channel select switch

Discussion in 'Amps and Cabs [BG]' started by jaguarcat311, Apr 8, 2005.


  1. i got a warwick pro tube IV amp with two channels, tube and solid state, i usually have my tube channel on a bit of overdrive and i would like to be able to switch channels with a footswitch but i cant seem to find a schematic on the net. its just like any other preamp that can use a footswitch, i believe a standard footswitch like a marshall would work, but those are pretty costly and i want to put a 1/4" jack on mine (the cables wired straight in always rip out)
     
  2. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    The schematic would show the 1/4 in. jack connected connected across the contacts of a SPST (single pole, single throw) switch.

    If the Warwick needs a two function footswitch and has a 1/4 in. jack, the two control terminals are probably tip and ring and the switching functions are activated by connecting either one to the sleeve.

    You'll have to decide on whether you need push on/push off switches or momentary switches. You can determine this by plugging an instrument (or speaker) cable in the footswitch jack and then causing switching with a screwdriver (or similar metal object) between tip and sleeve of the plug. If you have to leave the metal object in place then you need a push on/push off type switch. If you can just touch it to cause switching, then touch it again to switch back, then you need a momentary switch.

    Does this help?
     
  3. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    Will it really be less expensive to build your own rather than buying a pre-built one?

    By the time you find a switch, a suitable case (sturdy!!!!), a jack, a cable, etc. (especially if you have to pay shipping on any of these pieces) you'll be amazed at how quickly the cost will surpass that of a commercially available footswitch.
     
  4. k i figured out it takes a mono cable, and it switches by connecting the tip to the sleeve, and it needs on/off, not momentary. i just picked up my amp from the shop today and they cut me a deal on a marshall footswitch, but it doesnt work to switch the channel for some reason, im gonna try to mod it to work. ill let you know what happens
     
  5. alright, i opened up the marshall pedal, theres a red wire in to the middle pin, a resistor going to a diode and the other side of the diode going to the third pin where the white wire was soldered. i desoldered the white wire and when i wrap it around the unused pin, the footswitch works like it should, so it looks like the diode with the resistor is still grounding out the wire, so maybe a different resistor to stop it from grounding it. the voltage is probably slightly different or the amp is more sensitive than a marshall. im pretty sure the resistor is brown black black brown brown, but it could be orange instead of brown, it looks like a 10 ohm 1% tolerance, but it could be 30 ohm 3 % tolerance, and i believe that it is 1/2 watt
     
  6. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    If it works fine without the resistor and diode connected, I'd just leave them disconnected...
     
  7. Mezzoid

    Mezzoid Guest

    Apr 10, 2005
    maryville, tn
    I have just a little bit of electronic knowledge, so I may be wrong about this. To my knowledge, the reason to have a resistor across the switch is to prevent line surge when it's engaged. You would notice it as a big thump when you click from one channel to the other. I've seen a schematic that has a 1 Mohm resistor completeing the path across a switch, but it doesn't bypass it, it just keeps it warm for the real connection.
     
  8. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    Yes, you're probably right. The resistor/diode network tames the inductive kick that the relay coil gives when de-energizing it.
     
  9. hmm. im not so sure i understood that last post, my amp doesnt have the big pop sound when switching channels, its a fairly quiet click, not even as loud as stepping on the footswitch. i have left the diode out, but it would be really nice to have a diode on for the overdrivin channel ya know. i played a show last friday and i had to look at my amp to see if the lights were red or green to know which channel i was on sometimes (couldnt hear cause of the loud guitar player).
     
  10. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    I know this is a pretty simple product, and it probably doesn't matter much which one to use, but does anyone have a recommendation for a simple, sturdy, footswitch that I can use to bypass/engage my Chandler Tube Drive (it just takes the "standard" footswitch)? I'd like at least a 15' (preferably 20') cord.

    Thanks, Tom.
     
  11. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    The signal shouldn't be traveling through the footswitch. The footswitch ummm switches a DC voltage to either energize a relay or otherwise cause some sort of solid-state swith to change states.

    The diode in the footswitch is there only to reduce noise and perhaps to facilitate switching by making sure that the switching voltage goes to 0 volts when you want it off...
     
  12. Mezzoid

    Mezzoid Guest

    Apr 10, 2005
    maryville, tn
    to my knowledge, diodes are there to shunt DC current(or maybe it's voltage) one way and flow the other way, like a one way street. It takes two diodes opposed in parallel to create a distortion circuit. As for a footswitcth, the basic operation is: The switch (the thing you stomp on) either opens or closes a connection between the tip and sleeve of a mono cable. A two button does the same thing except it uses a TRS cable with connections from tip-sleeve and ring-sleeve, and 3 switch adds tip,ring-sleeve, as far as I can tell.