using spst switch

[elbow667]

Hello, I have a question that's going to expose me for the noob I am but I have been searching and not finding what I am looking for so...
I have a project I am working on, I am down to the final connections to the pots, switches, input output jacks.  The project calls for an SPST switch. So I purchased one from Tayda.
Its a rather simple switch, only two lugs and the switch doesn't click like I would expect it just goes up and down and I suspect its working as designed but wouldn't this mean that the pedal I am working on would only operate as long as I am holding my foot on the pedal?  I don't know how sensitive things are here or I would post the link to the project file I am working off of; its one of the tagboardeffects layouts if that helps.  The only reason I ask is because all the pictorial examples of footswitch wiring I have ever seen shows a much more complex switch with many more lugs and now I am wondering if I have the wrong thing.  I know there are different types of switches but the notes on the layout only say "Switch is SPST" and nothing else.  the switch I purchased is this http://www.taydaelectronics.com/spst-momentary-soft-touch-push-button-stomp-foots-pedal-switch.html
If you want the link to the project just say so, I just thought I would ask this question first and see what kind of response i would get.
thanks,
Don

[PRR]

> the switch I purchased is this ...spst-momentary-soft-touch-push-button-...
>  the switch doesn't click ....it just goes up and down....the pedal ....would only operate as long as I am holding my foot on the pedal?

The key word is "momentary".

Like a door-bell-- it rings only as long as you lean on the button.

Go ahead and tack it in. It will work for testing: you can always put a brick on the button.

It probably does matter which "one" of the many projects this is for.

For most simple pedals: a Momentary is no good for the stage.

As you thought, a latching switch will almost always "snap" to one position or the other. Like a clicky ballpoint pen. It has mechanical "memory" to hold a position.

There ARE projects where the momentary contact is held and alternated to electronic switching. Common in factory gear, less common in home-brew. And the fact that "SPST" is cited suggests this *may* be one of those. We like to switch 2 or 3 circuits to cut an effect (and LED) in and out. The one pole may be controlling multiple things in the electronics.

[elbow667]

thanks I will use this switch for testing, it was only 2 bucks so if its not going to work I think I will survive.  If SPST is really what is needed, would there be another type of SPST or footswitch I should be looking for?  I am only seeing momentary in the foot switch style, some of them are usually open or usually closed.  I think the one I have is usually open.  I have been looking around it seems Im not the only one that has been interested in this pedal so maybe its ok to post the link?  its the V3 of the ocd pedal clone http://tagboardeffects.blogspot.com/2012/02/fulltone-ocd-all-versions.html
much appreciated,
Don

[elbow667]

Ok, I think I understand where my inexperience led me astray.  the spst is not a footswitch but another smaller switch that turns on and off a higher gain setting.  I guess all the details of actually wiring in the footswitch is left out and up to the end user (me) to research and figure that out.  I guess that's where I'm at now thanks!

[antonis]

In OCD the switch doesn't latch anything...

It selects between HP/LP connecting (or disconecting) the 22k resistor in parallel with the 33k one...

So you need a latching SPST ON/OFF switch...
(maybe a small lever one - if you don't want to stomp on it..)

[smallbearelec]

Ok, I think I understand where my inexperience led me astray.  the spst is not a footswitch but another smaller switch that turns on and off a higher gain setting.  I guess all the details of actually wiring in the footswitch is left out and up to the end user (me) to research and figure that out.

That's exactly right!

For the New Year, a few observations that I hope will help you:

The layouts at Tagboard are fine and useful once you have some experience and can fill in things that the designer presumes that you already know. Also be aware that, by the nature of these stripboard builds, you don't really see the flow of the circuit; for that reason, I don't recommend them as first builds for beginners. Ideally, your first build should require you to interpret a schematic, and it should then walk you through laying out the circuit on perfboard.

As a couple of the other posters have noted, the switch that you mentioned turns some filtering on and off. It need not be a foot switch; an ordinary toggle switch would be fine for this function. A stomper (foot switch) will be wanted to switch the effect in and out, and it would typically be one like this:

http://smallbear-electronics.mybigcommerce.com/cic-blue-3pdt/

It's a latching switch, and it will provide the action you need with provision for lighting an in-use LED. But as I noted, the layout drawing presumes that you know all of this and that you know exactly how to wire the stomper. If you do succeed in getting the OCD working without in/out switching, ask again about how to wire the input, output, and bypass switching.

Here is a link to my beginner FAQ:

http://diy.smallbearelec.com/HowTos/BeginnerArticle/BeginnerDos.htm

Happy Construction and Happy New Year!

Regards
SD

[PRR]

OK, I see what it does.

You sure can test with this momentary switch, but for most uses I think you want a click-on / click-off switch.

Actually it works fine without that switch. Just gives you two options: more and MORE. Not a lot of difference from just working the amp Volume knob, but convenient to have two choices at your foot instead of over at the amp.

Read SmallBear's post. Read his Beginner Docs. Read the post and the Docs again. There is a lot of "common knowledge" which nobody can figure out at first. We thank "Bear" Steve for writing it up for everybody's benefit.

Now...  points which may not be in the Docs:

* Sometimes you want Momentary (door-bell), sometimes you want "Latching" (light-switch). This may be real obvious to the project designer, not to someone who just came to the project. For some staccato styles, a momentary switch here may be good for "stutter". Other styles may want Chorus/Bridge switching where a latching is better than standing on one foot through your solo.

* If you need a SPST, but can't find one, you can use a "more" switch. SPDT, DPDT, even 3PDT, and just use the contacts you need.

Remember the movies Frankenstein and Young Frankenstein? The doc turns-on the monster with a big knife-switch. It has two big copper bars and contacts both up and down. DPDT. Well heck, you only need one contact to turn-on a monster. But a monster needs a big contact, and big-contact switches usually switch factory loads where you have multiple wires, so the original doc (and the film designers) used the DPDT.

Obviously you pay for the extra contacts. But most of a switch's cost is the base/body, handle/button, and store overhead. In DIY quantities the price difference is often minimal.

The doc sends Igor to Transylvania Electric for a big SPDT switch. They have DPDT in-stock for $50, a SPST is $45 but special-order 8-week delivery. Igor slowly thinks: in 8 weeks doc will be in a foul mood, in 8 weeks the dead-meat monster will have a foul odor, the DPDT will work by ignoring the extra contacts, he takes the too-good switch.

The Most Common latching switches suitable for pedals are normally stocked DPDT and 3PDT. (However there is a SPST sold for old amplifier Reverb switching.)

(Yes, you found a $2 part and Bear points to a $5 part. Switch quality, reliability, ruggedness affect the price. Tayda stuff often works OK for a while. Bear's stuff DOES work in STOMP-pedals, or he makes it right for you.)

At Tayda, you can find "2PDT DPDT Latching Stomp Solder Lugs SKU: A-382". One of the reviews mentions "plastic melts too easy", which may be a user-problem or may mean it is made of cheap plastic.

[tubegeek]

[PRR]

Before that part. It takes time to boot a monster.

[duck_arse]

Remember the movies Frankenstein and Young Frankenstein? The doc turns-on the monster with a big knife-switch. It has two big copper bars and contacts both up and down. DPDT. Well heck, you only need one contact to turn-on a monster.

I've always loved young frankenstein, and off-topicing threads, so a quiz question.

a switch that has a pair of contacts above, and a pair of contacts below, and a shorting handle between: what is it called? double-pole, single-throw changeover? single-pole, double-throw changeover? not a dpdt, surely.

and I have one of these, a footswitch pulled from, I think, a "silversound" fender blender clone. it has two contacts each end, and a flying shorting bar-thing between.

[Digital Larry]

Sounds like a DPST to me (4 contacts total).

[PRR]

> two contacts each end, and a flying shorting bar-thing between.



?

Not any common type.

It can be replaced with a DPDT and a jumper, bottom scribble.

[akc1973]

OK, I see what it does.

You sure can test with this momentary switch, but for most uses I think you want a click-on / click-off switch.

Actually it works fine without that switch. Just gives you two options: more and MORE. Not a lot of difference from just working the amp Volume knob, but convenient to have two choices at your foot instead of over at the amp.

Read SmallBear's post. Read his Beginner Docs. Read the post and the Docs again. There is a lot of "common knowledge" which nobody can figure out at first. We thank "Bear" Steve for writing it up for everybody's benefit.

Now...  points which may not be in the Docs:

* Sometimes you want Momentary (door-bell), sometimes you want "Latching" (light-switch). This may be real obvious to the project designer, not to someone who just came to the project. For some staccato styles, a momentary switch here may be good for "stutter". Other styles may want Chorus/Bridge switching where a latching is better than standing on one foot through your solo.

* If you need a SPST, but can't find one, you can use a "more" switch. SPDT, DPDT, even 3PDT, and just use the contacts you need.

Remember the movies Frankenstein and Young Frankenstein? The doc turns-on the monster with a big knife-switch. It has two big copper bars and contacts both up and down. DPDT. Well heck, you only need one contact to turn-on a monster. But a monster needs a big contact, and big-contact switches usually switch factory loads where you have multiple wires, so the original doc (and the film designers) used the DPDT.

Obviously you pay for the extra contacts. But most of a switch's cost is the base/body, handle/button, and store overhead. In DIY quantities the price difference is often minimal.

The doc sends Igor to Transylvania Electric for a big SPDT switch. They have DPDT in-stock for $50, a SPST is $45 but special-order 8-week delivery. Igor slowly thinks: in 8 weeks doc will be in a foul mood, in 8 weeks the dead-meat monster will have a foul odor, the DPDT will work by ignoring the extra contacts, he takes the too-good switch.

The Most Common latching switches suitable for pedals are normally stocked DPDT and 3PDT. (However there is a SPST sold for old amplifier Reverb switching.)

(Yes, you found a $2 part and Bear points to a $5 part. Switch quality, reliability, ruggedness affect the price. Tayda stuff often works OK for a while. Bear's stuff DOES work in STOMP-pedals, or he makes it right for you.)

At Tayda, you can find "2PDT DPDT Latching Stomp Solder Lugs SKU: A-382". One of the reviews mentions "plastic melts too easy", which may be a user-problem or may mean it is made of cheap plastic.

You would have made a fantastic teacher, Paul. I wish 3/4s of my Uni lecturers had had your way of explaining things!

[duck_arse]

indeed, drawing the circuit makes it somewhat plainer. adding the "push" handle to your top drawing is what I've decided is a "double-pole, alternate single-throw", but I've been wrong about switches before. and I omitted the fact that the silversound switch had a shorting wire down one side, making a proper spdt.

that Igor, always with the trouble.

[Mark Hammer]

Once upon a time, stompswitches were hard to find, and cost a bloody fortune.  In the early 90's I could end up paying $20 for a DPDT.

These days, not only have the costs come down, and availability increased, but the price difference between a SPST, DPDT, and 3PDT is almost negligible to a hobbyist who goes through a handful in a year.  If you were a manufacturer trying to keep overhead down and offer competitive pricing, you'd probably be more attentive, but the price difference for a handful, within any given calendar year, is small enough that  it makes sense to buy 3PDTs, and use however many terminals/lugs/contacts you need to accomplish the electronic task.  If you only need 6 out of the 9 contacts, fine.  If only 2 out of the 9, fine too.  You've bought as many switches as you expected to need, and they all meet your requirements, even as those requirements vary.

Same goes for rotary switches.  Some brands of rotary switches come with a washer that has a tab to let you set the maximum number of positions.  So, a two-contact, six-position rotary will let you set it to have maybe only 3, 4, or 5 positions, if you wish, and a 3-pole/4-position can be configured to have 2 or 3 positions if you want.  Same principle applies, buy the switch that affords the most options, and only use the number of options required, leaving the remainder "fallow".

[elbow667]

I just want to say thanks to those who offered help. seems I lost track of the thread once I determined my problem.  I am very happy with my build despite that its very ugly.