where can i get transistors for my wah pedal?

[Tom F]

I need new transistors; does anyone know of a reliable place i could buy them off the internet?

[Mark Hammer]

Kind of a vague request. However, transistors used in wahs tend not to be very exotic. Unless you live somewhere very isolated, there is every likelihood that they can be purchased in your municipality for less than the cost of parts+shipping.

If you want true certainty in the matter, you can likely buy replacements from the manufacturer. Or if you are cloning something, then I would recommend Small Bear Electronics, who specialize in pedal parts, and especially exotic and hard-to-get ones.

[tekhed7]

Best place to buy original # Q's for consumer electronics is 1 of the OEM parts distributors. The friendliest I've found is MCM Electronics out in Ohio. Been buying silicon & what-not from them for almost 30 years now! Alway good-Q... & good selection, too.
Call up their 800# & ask for a catalog. There'll be a multi-column section w/ all sorts of transistors; from economical [2S]C945s at < 20 cents ea to Hi-Power stuff like MJ15024s
And, yes, they have a website. Google 'em if you kant spel wel.
If you have a vintage CryBaby wah pedal, you'll need a couple germanium PNP Qs.
They should have some, either an orig # or an acceptable sub.

[Tom F]

A better question i should ask is what kind of transistors should i get for my wah pedal? I don't want to go to radio shack and grab the wrong kind.

[tekhed7]

Well, Tom... that begs the question Why do you need to "put in" any transistors?
And what make & model is this "wah" pedal?
Old Thomas Organ Crybabys use 2 small, lo-noise Germanium PNP transistors. Newer ones use silicon "Qs". Other Wahs use chips ("I.C.s").

Rat Shack has crap for selection now. You'd be better to get them from a supplier.
Every major city usually has an electronics parts place though I would admit the #s continue to shrink as consumer electronics continues to shift towards total "throw away".

The parts, equipment, overhead & training needed, continue to climb as the circuit complexities increases and the final product cost drops. Who would EVER have imagined $69 color TVs in 1969! In FACT, that'd be more like 12 or $15 in 1969 dollars!!

[Robert M. Martinelli]

Hi,
"Italian made" vintage ( late '60s ) Vox wahs had a couple of BC109C inside, I have also used other Silicon low noise hi-gain transistors with excellent results ( 2N4104, 2N5210 ), and found the Japanese 2SC1815 to be the quietest ( noise-wise ). As Mark already noted, you don't need anything "exotic", however, if you're subbing the original BJTs with something different, be careful about the pinout.

JM2CW

Best regards

Bob

[52 Bill]

Old Thomas Organ Crybabys use 2 small, lo-noise Germanium PNP transistors.

I don't think that PNP Germaniums were ever used in any Crybabys.

The only wah that I've ever seen with PNP Germaniums was the original chrome Fender Fuzz-Wah pedal.

[Tom F]

Tekhed I have a vox v847 and one of the transistors isn't giving any resistance anymore so I just figured i would replace both of them. And Robert thanks for the info, but what do you mean about the pinout? I'm such a noob about this stuff.

[Mark Hammer]

Some transistors are emitter-base-collector, looking at it from the flat side with thepins facing down.

But some are emitter-collector base.

Round "button" type transistors can be emitter-base-collector, but with the pins in a triangle pattern.

The list goes on and on. The point is that you should not make assumptions about which pin of the transistor serves which function. You should either use a traistsor tester function on a meter to confirm the pins or else get datasheets for the transistors, which will show in a picture which pin is which.

[Robert M. Martinelli]

I don't think that PNP Germaniums were ever used in any Crybabys.

The only wah that I've ever seen with PNP Germaniums was the original chrome Fender Fuzz-Wah pedal.

I'm with Bill on this one.

AFAIK the first wah was invented by a Vox/Thomas EE named Stan Cutler in late 1966/early 1967, and, at that time, Silicon transistors were available already.

It's very unlikely that, with Si devices handy, Vox/Thomas R&D could have used Germanium BJTs while prototyping something new, given all the inherent ( and known very well already at the time ) weaknesses of Germanium transistors in terms of current leak, "gain consistency" and thermal (in)stability.

FWIW, I have repaired/restored several vintage "italian made" Wahs and even the oldest ones ( '67 ) sported Si BJTs.

JM2CW

Cheers

Bob

[Tom F]

which type is used in a wah pedal? emitter base collector or emitter collector base?

[Robert M. Martinelli]

Hi Tom,
I encourage you to re-read Mark's last post, if you look closely to the transistors inside your wah, you'll see there are some writings on them ( something like MPS-A18, 2N3904, BC239C and so on ). Once you have positively identified the transistors, you can look at their datasheet to figure out their pinout ( the terminals' arrangement ). If you're subbing them with different types, you have to check the new transistors' pinout before installing them as they could ( or couldn't ) match the subbed transistors' pinout.
Should the pinout be different you'll probably have to either rotate the transistors or to bend the pins ( being careful the pins don't touch each other ) to have each one of them in the "right" hole.

Hope I managed to make it clear enough, and hope this helps

Best regards

Bob

[Mark Hammer]

It is usually possible to find the datasheet posted for almost any component you are interested in by googling <part number> + "pdf". So, googling "MPSA18 pdf" gets us this as the first hit: http://www.fairchildsemi.com/ds/MP%2FMPSA18.pdf The very first page of the datasheet shows it to be an E-B-C pinout.

It is often a good idea to try a couple of manufacturers for any transistor, just to be absolutely certain that they all adopt the same pinout, because sadly, sometimes they don't. If you know that the datasheet you have is for the same manufacturer as the tranny you are looking at, fine, but sometimes you may not be able to recognize the manufacturer logo or it is scratched or whatever. In those instances, it is worth the extra effort to dig a bit and confirm that several manufacturers all use the same pinout. Much much easier to do that than to THINK you have the correct pinout and drive yourself crazy troubleshooting. Personally I find the choice between an extra 5 minutes and an extra 5 days easy to make.

Alternatively, many very basic digital multi-meters come with a transistor-testing function. This essentially measures potential gain or "hfe". The individual socket pins are labelled so that you can easily tell which different pinout you are exploring. I find this invaluable for testing transistors I am unfamiliar with, or those whose markings are hard to make out, or unusual form factors where the pins may not be in a straight line.

You can always expect an hfe reading of at least 100-150 (and often more) when the transistor pins are inserted into the right socket pin. Re-test by selecting the opposite polarity/type (NPN or PNP, whatever is opposite). If you don't get a plausible reading, consider trying out one of the alternate pinouts to see if that gets you something that makes sense (the reason why DMM transistor sockets are often 4-pin labelled E-B-C-E, so you can try EBC or ECB easily). Be sure to make a note of which way the transistor was facing.

[Steve Conner]

Let's rewind here. Is the wah pedal actually faulty? If so, how did it break? Unless you plugged it into a speaker output jack by mistake, or hooked up the power backwards, it's unlikely that any of the transistors in it are blown.

[Tom F]

alright rob you did clear that up for me. I'm gonna go ahead and start getting work on this thanks to everyone who helped out.