New guy here.....go easy on me!! haha- question about correct SPDT to use?

[plexi12000]

greetings !-- i'm new to the whole pedal build-mod-tweekin' thing. shew....i jumped in a BIG pond.  but it sure is fun.  i'm just a "hobbyist" and trying to have fun and learn more about their operation.
i'm pretty good with basic tube amplifiers...but i've QUICKLY realized just how insanely difficult it is to understand stuff like op-amps, transistors and the like.  wow. 
wish i would have learned "theory" when i was YOUNG!! dang...  -lol   But....this forum looks like a good place to start. So, thank you in advance for any assistance!

I guess if we mention products, etc. we are suppose to try to keep things anonymous as much as possible....i'll attempt to do that with my question.  I built my first tube screamer 808. great results...love it.
Going to try another one...and i'd like to add a modification called the "fat mod"?  It bypasses a capacitor for a boost and bass increase, with a SPDT toggle.

Not sure about the actual switch to use though.  Should it be a "on-off-on"...or "on-on"?  Thank you.

[GGBB]

Sounds like your really only need SPST on-off - but without a diagram/schematic of the mod - who knows. An on-on SPDT can be used in place of an SPST.

[peterg]

Welcome to the forum.

If the fat mod is as per the Madbean Tube Screamer schematic:

http://www.madbeanpedals.com/projects/GreenBean/docs/GreenBean2014.pdf

Then you need an "on-off-on" SPDT switch.

[plexi12000]

thanks-   yes, i think its the same from a quick view of that layout....thank you!  the layout/schematic i have is from "AMZ"?  it shows a single pole toggle...but only has two solder lugs...no "center" lug. 
....that kinda confused me.   and i have a tendency to over-think everything.

The switch bypasses C3 (.047uf) on my layout. two wires run to the switch.  looks like on the green bean, he uses an "on-on".   

think that's the way to go?

[peterg]

The Madbean scheme shows a SPDT on-on switch - 3 lugs. My original note is wrong.

The AMZ scheme hows a SPST on-off switch - 2 lugs.

I made the Madbean pedal and the mod works well. The AMZ mod is simpler.

[plexi12000]

aah- ok.  so the AMZ mod..is an "on-off", two lug switch.   i'll have to take a closer look at the madbean mod too.  maybe try that.

hey, thanks for your help peterg....i appreciate it!

[steveyraff]

I'm doing the AMZ booster with the fat mod. The mod they show says that its a centre OFF with fat ON at one side and 'fatter' ON at the other side. See diagram here: http://www.muzique.com/news/mini-booster-fat-and-fatter/

So I ordered some ON-OFF-ON switches. Heres the problem though, they always go back to centre position. The don't seem to 'stay' at ON positions and always return to centre. Can someone tell me what I've done wrong here? I presume I've bought the wrong kind of switches.

Thanks!

[plexi12000]

oh thats cool---  not sure what manfacturer made your switch.....but i'd use a Carling. their "on-off-on" will work fine for years.

let me know how that mod goes.  it'll be a few days til i try it.  need to order a swtch.

[plexi12000]

yes--- sounds like you may have ordered the "wrong" ones.

[plexi12000]

hmm...looking at Carling website and their "mini" toggles.  don't see any "on-off", let alone any with just two lugs.   

[peterg]

Sounds like you have momentary switches.

[bloxstompboxes]

http://smallbear-electronics.mybigcommerce.com/search.php?search_query=spdt

One of the 'center offs' should work.

[GGBB]

hmm...looking at Carling website and their "mini" toggles.  don't see any "on-off", let alone any with just two lugs.   

An SPDT on-on (3 lugs) will work fine in place of an SPST on-off. When you only use two lugs, on-on effectively becomes on-off.

[plexi12000]

GGBB...... thank you!  so, i'm guessing i would use the center lug for "off"....and one of the outer lugs for "on"?

[PRR]

> ON-OFF-ON switches. Heres the problem though, they always go back to centre position.

That's "momentary". Like a door-bell. It only rings as long as you lean on it.

Lamp switches that stay lit all night without constant press are "latching".

I have noted that MOST switch sellers are not very good about pointing-out this difference.

Especially they almost never say "latching".

However the words "momentary" or "mom" in a switch description or part-number should be a red-flag.

Sometimes you DO want momentary. Stutter-buttons especially. Cough-switches. Maybe a "quick tune" function. Also Tap-Tempo. Many fancy/commercial pedals take a momentary press and "latch" it in internal logic controlling signal paths.

But if you want a simple mechanical switch to stay-on through your solo without standing on one foot, "momentary" is not right.

[plexi12000]

good information, PRR  --thank you

[bluebunny]

So I ordered some ON-OFF-ON switches.

As Paul noted, you've scored some momentary switches.  You often find these written as (ON)-OFF-(ON), where the parentheses indicate the momentary action.  Here's a couple of examples from Bitsbox:

[GGBB]

GGBB...... thank you!  so, i'm guessing i would use the center lug for "off"....and one of the outer lugs for "on"?

Not quite. Lugs aren't on or off - they are connected or disconnected to each other. In the case of the AMZ Fat Bass for Tube Screamers mod, all it does is connect a wire across the cap. One lug connects to one end of the cap, the other lug connects to the other end of the cap, and with an SPDT one of those lugs has to be center/common. So the mod is "on" when the two lugs are connected together (switch is closed).

"On" and "off" are actually descriptive terms related to what you are doing rather than part of or the function of the switch.  For example, a switch that shorts a signal to ground could be labelled "off" when it is closed/connected because your are turning the signal off by shunting it to ground. However, in switch nomenclature, on means closed/connected and off means open/disconnected.