Interesting wah

[Mark Hammer]

Several years back, I was given a wah by a local vintage-gear fellow, that was more or less in pieces and non-functional.  I put it at the back of a bottom drawer, ne'er to be seen, but rediscovered it this evening while looking for something else.  I wasn't sure whether it would merit the effort to make it serviceable again, and dug around for a Youtube demo to persuade me one way or the other.

It's an Ace-Tone WM-1 Wah Master, Ace-Tone being the brand name of what would eventually become the Roland Corporation.  It wasn't immediately obvious, but I learned from the video that it is a "switchless" wah, and quite possibly the first such production unit.  By "switchless", I mean that it is in bypass mode until you step on it, at which point it goes into effect mode, reverting back to bypass when you lift your foot.

Well, actually, that's a bit misleading.  There is a microswitch lever under the foot treadle, and when you move the treadle a little forward, it presses down on the actuator level.  The treadle is spring-loaded, so when you lift your foot, the treadle immediately goes heel down and switches back to bypass.  Power is a 9V battery, and uses an on-off slide switch to apply power

Of course, the nature of the bypass is still a mystery.  Haven't disassembled the unit enough to see the circuit inside.  It obviously doesn't require a status LED, but they certainly didn't make DPDT microswitches in the '60s, either.  So chances are pretty good it's a normally-open or normally-closed SPDT switch.  The fact that the treadle has to be moved a little to engage the effect means there is a bit of a lag until your foot makes it wah, since the spring makes it always start from the heel-down position.  But as the video illustrates, the fluidity of being able to have momentary switching in such a unit is nice.  I hope to eventually dig in and see how it operates electronically, and if there is any way a buffer could improve things.  BUt for now, more than a curio.  I kind of like it.

[Rob Strand]

Some pics here,

http://effectsfreak.com/effect/ace_tone/wm-1_wah_master_/

The unit in the vid has sloped metal work but some of the other pics don't look like they have such a pronounced bend in the metal.

[PRR]

> didn't make DPDT microswitches in the '60s

They did; but not for this market.

The pix in Rob's well-found link show a MicroSwitch-clone SPDT used as SPST. (Same image, two servers.)
https://a.disquscdn.com/uploads/mediaembed/images/688/7386/original.jpg
https://i.postimg.cc/V6vWY4CM/original.jpg

[Rob Strand]

[OT]

> didn't make DPDT microswitches in the '60s

They did; but not for this market.

First microswitch Omron 1943.

https://www.omron.com/global/en/assets/file/ir/irlib/ar20e/OMRON_Integrated_Report_2020_en_05.pdf

I remember a lot of microswitches (or limit switches) on industrial machines in the 70s, some of the machines were old and from the 60's for sure.   They were often a palm size assembly with an arm.  Can't say when the individual switches as we know them came out but I had some Omron ones in the early to mid 70's.

[/OT]

[Mark Hammer]

My experience with micro-switches comes from animal research labs; chiefly boxes where pigeons or rats had to peck/press a lever to get food, but you didn't want the lever to require a lot of pressure to actuate.  These were nearly always 3-contact units, wired as N.O. or N.C..  I still have a pile of them, salvaged from equipment.

Thanks for the detective work, and resulting pic, Rob.  Much obliged.

Actually, there is no "sloped" metal.  No curves anywhere to be found.  The folded-metal treadle affixes to the internal mechanism via 4 screws, and the rubber mat sits on top of the metal treadle.  Given its age (50 years+), I gather the rubber doesn't perfectly grip the metal plate, making it look slightly curved.

[anotherjim]

The only DPDT microswitches I've seen were obviously x2 SPDT riveted side by side and sharing a wider operating lever. DPDT limit switches are common, but I've only seen fairly chunky industrial strength ones. Although that Ace wah looks big enough for one!

[11-90-an]

You made this thread before, M.H.,

https://www.diystompboxes.com/smfforum/index.php?topic=111322.0

No schem I believe, so

*ahem ahem* gutshots? *ahem* 

(Yes, I'm quite bored, and I love a good trace, sorry...)

[Mark Hammer]

Well clearly I need to start sprinkling some Gingko Biloba on my Wheaties in the morning, because I don't recall starting that thread.

Prompted by responses here, and the posted pics, I took it apart, and hope I can re-assemble it.  I'll need to clean some things first before taking and posting any pictures, but here preliminary info:

1) As anticipated, the microswitch is SPDT in the late 1960s arrangement of the output jack taking its feed from either the input jack or the output of the circuit.

2) No inductor anywhere within 10ft of it, so I gather it is some sort of twin-T kind of bandpass filter (to be confirmed following cleanup and drawing of the schematic)

3) Uses two house-numbered "button" type plastic transistors, 4 electros, 3 greenie caps, and a lot of 100k resistors.


More to follow.  Right now, the leaves need raking.

[willienillie]

They were often a palm size assembly with an arm.

I've got so much old junk.



SPDT, still works.  Arcade-style button.  What might be a date code indicates 1972, 30th week.  Pinball machine?

[Rob Strand]

FWIW, quite possible the Ace Tone Twin Ace FW-1 uses a similar circuit.   This one is later than the WM-1, perhaps early to mid 70's.

http://electricpartslibrary.hatenadiary.jp/entry/20131127/p1

You can see the wah pot uses only two pot terminals and is connected to ground.   So like you say Mark, highly likely to be a Twin-T.

I wonder if that's where the colorsound design originates from WM-1?

Actually, there is no "sloped" metal.  No curves anywhere to be found.

I think it was just an optical illusion in that side shot.

SPDT, still works.  Arcade-style button.  What might be a date code indicates 1972, 30th week.  Pinball machine?

Quite possibly Pin-Ball.    I remember seeing a lot of "cheap" brass-leaf contacts in Pin-Balls.  They use contacts for detecting balls in channels and stuff like that.

[willienillie]

Many years ago I worked in an arcade for a few months.  I don't think I messed with any pinball machines, but I replaced a number of Skeeball microswitches, they were triggered when a ball went in the hole.  The video games had different switches, cylindrical plastic things.

[PRR]

...First microswitch Omron 1943....

Omron is, I believe, a copycat.

MicroSwitch, brand and concept, goes to before 1937.
https://en.wikipedia.org/wiki/Miniature_snap-action_switch
https://web.archive.org/web/20110207050757/http://sensing.honeywell.com/1/4/6/5/5/8/index1.shtml

"1972
A 1942 WWII Hurricane bomber was recovered from a Canadian swamp. The plane has been under water for thirty years, yet a MICRO SWITCH device in the cockpit was still intact, still sealed and functioning."

"1975
A Honeywell MICRO SWITCH HM switch has survived the 505 million mile journey to Mars aboard the Viking Mars Lander. The switch is on the retractable surface sampler, which will scoop up Martian soil and deliver it to the biological laboratory."


But the point may have been DPDT switches. Multiple poles won't snap at the same time so are rare in precision switches. (Yes, would work for a wah cut-out, but that's not a big market.) (As Jim says, you can hack two together, maybe close-enuff for Mark's mice tests.)

I do like this snippet from the Omron notes on Japan 1955: "...3 essential tools for modern life: TV, electric washing machine, and electric refrigerator, which were called Sanshu no Jingi (known as “Three Sacred Treasures)."

[Rob Strand]

Omron is, I believe, a copycat.

MicroSwitch, brand and concept, goes to before 1937.
https://en.wikipedia.org/wiki/Miniature_snap-action_switch
https://web.archive.org/web/20110207050757/http://sensing.honeywell.com/1/4/6/5/5/8/index1.shtml

It sure does.

Seems like it started off as MICRO SWITCH Corporation but somewhere in the 40's Honeywell got involved.

Here's a timeline with pics continuing from the 75th Anniversary links you posted,

history_timeline_pdf

I suppose if you want to be really old-school you can mechanically couple two SPDTs. 

[iainpunk]

someone once told me that the micro refers to the power it takes to snap it over, not the actual size. i really don't know if that's true, but is sounds quite plausible.

cheers, Iain

[Mark Hammer]

FWIW, quite possible the Ace Tone Twin Ace FW-1 uses a similar circuit.   This one is later than the WM-1, perhaps early to mid 70's.

http://electricpartslibrary.hatenadiary.jp/entry/20131127/p1

You can see the wah pot uses only two pot terminals and is connected to ground.   So like you say Mark, highly likely to be a Twin-T.

The WM-1 uses the exact same pot, and also uses a cam rather than rack-and-pinion to rotate the pot.  I repaired a buddy's Royal fuzz-wah a few years ago and it also used a cam.  I have an early-version Visual Sound Volume pedal, which also uses a cam to move the pot, only i that case it moves a slider, rather than rotary pot.

[PRR]

...Seems like it started off as MICRO SWITCH Corporation but somewhere in the 40's Honeywell got involved....

1950 Honeywell purchases the MICRO SWITCH Corporation.
https://web.archive.org/web/20110209015243/http://sensing.honeywell.com/1/4/6/5/6/1/index1.shtml

Burgess (battery) got a contract for chicken brooders. They could not get good switches so they made switches. They were good for other work. In 1937 employee Schulte bought that side of the operation away from Burgess to trade as MICROSWITCH. A LOT of war-work, in which it was practical and convenient to leave ownership as-is. (Honeywell may have been 2nd-sourcing for the war.) But post-war management fads suggested conglomeration, and Honeywell was a good fit in market and money. Seems to have worked out.

[soggybag]

Reminds of the more recent Plutoneium Chi Wah.

https://www.plutoneium.com/index.php/product.html

I have one of these and it works pretty well. From what I can til it uses an optical mechanism to engage and disengage the effect.

[Rob Strand]

1950 Honeywell purchases the MICRO SWITCH Corporation.
https://web.archive.org/web/20110209015243/http://sensing.honeywell.com/1/4/6/5/6/1/index1.shtml

Good find.   They web page actually has a lot more info than the PDF.

The WM-1 uses the exact same pot, and also uses a cam rather than rack-and-pinion to rotate the pot.  I repaired a buddy's Royal fuzz-wah a few years ago and it also used a cam.  I have an early-version Visual Sound Volume pedal, which also uses a cam to move the pot, only i that case it moves a slider, rather than rotary pot.

It's interesting how in the early days you see a lot more ideas then they weed themselves out over time.   Another variation is the pot winding cw vs ccw when the pedal is down.