Easy question (hopefully) about switches

[licksville]

First let me qualify myself as a rookie/hack with a soldering iron, but that will probably become obvious based on my question.  I bought a Fender Mustang II amp.  It has a footswitch jack which will allow you to toggle between two presets on the amp but does not come with a footswitch.  I, thinking that I knew what I was doing, ordered some parts from mouser - a metal stompbox and a SPST footswitch.  As it turns out, when plugged in the SPST engages one of the two presets, but will only engage the second preset if I hold the switch down.  Seeing this behavior, I believe I now fully understand what 'momentary on' means.  My question is, will SPDT do what I need it to do and should I be specifically seeking those SPDT switches marked as on-on?  Does on-on signify latching?  Also, I've found at least one SPDT switch labelled as on-off / momentary on, which didn't seem to make sense based on my understanding of what DT means.  Thanks in advance for your sage wisdom.

[PRR]

Throws and latching are two different things. A doorbell is SPST momentary. A wall switch is SPST latching.

A garbage-crusher could be on-off-on_mom. Off for idle, on (latched) for retract, but the on for Crush might be momentary to force you to stand there and watch for hands or cats getting crushed.

> Easy question ... a Fender Mustang II amp

Switching on post-1980 amplifiers is NOT easy. In 1959, foot pedals were as simple as light switches. Short-out a frill to make it stop. But cheap chips made it "easy" to add more and more frills, especially LED in the pedal so you know what mode it's in. You want to find the factory schematic. It may show pedal guts. If not, maybe the pedal system can be reverse-designed from what the jack-chips can do.

[PRR]

Man, that Muskrat II is a COMPLEX beastie.
http://support.fender.com/manuals/guitar_amplifiers/MustangI_II_advanced_manual_English.pdf

However it appears the footswitch is simple. One button, no LEDs??

It's only $13. Just buy one, save DIY for something more interesting.

Must DIY? Try this. Gitar cord to pedal jack. Tap a coin on the far end of the cord. If the amp lights switch on each good tap, you want SPST Normally-Open Momentary. All the full-line pedal-parts stores have such a thing.

www.SmallBearElec.com, Stocklist, search "momentary":
Switch - Carling 110-PM-OFF Momentary Stomp
Extra-rugged, momentary NO contacts, for logic-switched pedals... $8.35
Switch - Momentary SPST "Soft-Touch"
Rugged enough to be stomped, but you don't have to! Short, light stroke, with positive action. Normally Open operation. $3.95

[licksville]

Thanks for the insights.  Yeah, I'm aware of the fender foot pedal but my experience with hard-wired channel-switching pedals is that, sooner or later, they stop working because of wire issues.  I prefer channel switching pedals that allow you to connect/disconnect simple TS or TRS cables, hence my decision to 'roll my own'.  Regarding your suggestion of SPST Normally open Momentary, that's what I purchased and that's what produced the behavior that I described.  When I plug in the footswitch cable, the amp immediately switches to one of the two presets established for the foot pedal.  When I depress and hold the SPST switch, the amp switches to the second preset established for the foot pedal, but when I release the switch it reverts back to the first preset.  So, if I understand the terminology correctly, I need a latching switch and ST/DT doesn't have anything to do with it.  I thought that double throw suggested that 2 different states would be produced by consecutive engagements of the switch.  I will look for the latching designation.

[johopki]

I have the Mustang I and I'm curious if you found a fix to your problem.

[Mike Burgundy]

regular *latching* switch for all Mustangs v1 and v2, afaik.
Edit: I and II v1 and v2.
III and up can support more complex switching.