Mislabeled NC momentary from Small bear heads up

[midwayfair]

Normally off = normally open.
Remember a switch is OFF when the circuit is SHUNTED, i.e., not connected. The simplest place we find this is a light switch. When you turn the switch off, it breaks the connection and no current flows through the bulb.

Normally closed = normally on.

It's rare, but it's possible someone at Tayda mixed up the abbreviation "NO" for for "normally on." In fact, the "O" is probably the reason the words "closed" and "open" are used instead of "off" and "on".

According to the above, you bought a switch at Tayda called a "normally open" switch and discovered that the lugs were connected when the switch was NOT pressed. This indicates that it's a normally closed switch, and they made an error. You thought that you had ordered the wrong type of switch, so you ordered a normally CLOSED from Smallbear.

so I ordered a normally closed switch from small bear

Which worked the same as the Tayda switch.

[jimilee]

Oh I get it, thank you, so then the one I bought from blms was mislabeled. But I like it better because I don't get the runaway oscillation and it works like the latest video of the zpsdx posted in the June section. So then that begs the question, do you think the BOM  should be changed? Several builders were experiencing the runaway oscillation.

[DutchMF]

I use these: http://www.taydaelectronics.com/electromechanical/switches-key-pad/stomp-switch/2pdt-stomp-foot-pedal-switch-solder-lugs-2.html

They are a bit bulky but can be used as both normally open and normally closed, which is enough for me to have some in my parts bin. Plus, they look exactly the same on the outside as a 3PDT, which I like! I've seen some builds around here with two different footswitches side by side, something I would never do (no offence....)

Paul

[jimilee]

Thanks Paul, I think I will grab a few in my next order. I have another zero point pcb to build plus these seem to be common in the things I like to build. Man this delay is awesome now that I got all the bugs worked out.

[midwayfair]

So then that begs the question, do you think the BOM  should be changed?

What are you suggesting needs to be changed in the bill of materials? Certainly not the type of momentary (NO vs. NC)? The reason the switch does its thing in the first place is that as you turn up the feedback pot, the closer you get to 0 resistance between lugs 2 and 3 (and assuming the resistance to ground is >0), the less feedback is shunted to ground. Swapping the type of switch would in fact make it oscillate all the time above 0 on the feedback pot. There is no situation in which a normally closed (normally "on") switch is the proper switch to use, and using it will not help if you are dissatisfied with the feedback pot without the switch connected. If you remove the switch entirely, the pedal should work exactly the same as when you are not pressing the switch. If that's not true, then you have something wrong.

The only truly useful change if you find feedback happening too early is to use a log taper pot. It will spread out the range more. You can make it even more log-y by sticking a 12K or so from lug 1 to lug 2, and the resistance to ground will always be less (= less feedback).

However, if you're talking about taming what the oscillation switch does, basically, controlling how quickly it permits oscillation, check my build reports for the Joshua Tree, Hamlet, and ZPSDX; I describe using a trimpot to dial in the oscillation exactly. Given that there's pretty much zero space (hah) left on the PCB, though, I wouldn't count on Brian adding that functionality to the stock design ...

[jimilee]

It was just a question while I'm trying to figure it all out. With the switch reversed I am able to control the oscillation and now my build works exactly like the latest video that was posted. I don't pretend to suggest I know better than the BOM by any means, so please don't take it that way. I'm just trying to understand it all. Now mine doesn't oscillate out of control until I push the switch. One thing I like about this community is the freedom to exchange ideas. Thanks so much for your knowledge, I greatly appreciate you.

[RobA]

It was just a question while I'm trying to figure it all out. With the switch reversed I am able to control the oscillation and now my build works exactly like the latest video that was posted. I don't pretend to suggest I know better than the BOM by any means, so please don't take it that way. I'm just trying to understand it all. Now mine doesn't oscillate out of control until I push the switch. One thing I like about this community is the freedom to exchange ideas. Thanks so much for your knowledge, I greatly appreciate you.

I'm confused. I have a pretty solid feeling that the BLMS SPST and the Tayda SPST are the same switch (from looking at the two sites and having a Tayda version in hand). The Tayda switch is an off-(on), which should be the right one for the circuit.

Did you check the continuity of the BLMS before you put it in?

It would probably be good for the build doc to directly say what type of momentary is needed in the BOM. I know that it says it in the detailed instructions, but it would help to have it spelled out in the BOM.

[midwayfair]

It was just a question while I'm trying to figure it all out. With the switch reversed I am able to control the oscillation and now my build works exactly like the latest video that was posted. I don't pretend to suggest I know better than the BOM by any means, so please don't take it that way. I'm just trying to understand it all. Now mine doesn't oscillate out of control until I push the switch. One thing I like about this community is the freedom to exchange ideas. Thanks so much for your knowledge, I greatly appreciate you.

Jimi, I'm just trying to get you to think about how that part of the schematic/circuit works. I'm sorry if I sounded ... cantankerous.

[jimilee]

No it's cool, I was being honest with you, and I do learn from you and I thank you for sharing your knowledge.