Any use for a 2N6520 PNP?

[Will.mendil]

Hi,

I got about 200 2N6520 transistors but I cannot find anything to do with them related to stompboxes. Has anyone got any idea? ideas of pedals to directly use 2N6520 or something the 2N6520 could substitute.

Cheers

[Kipper4]

Sorry just had to.

http://www.diystompboxes.com/smfforum/index.php?topic=106068.0

[PRR]

Aren't many pedals which need a 300 Volt PNP.

30V parts are cheaper, and have higher gain.

You could use it as jellybean PNP. The 30X breakdown margin does no harm (assuming you didn't pay showroom price) and the low hFE may not matter in many circuits.

[LucifersTrip]

It really depends on the hfe...and as noted by PRR, they're probably low.  If hfe 80-100+, you can use em for many vintage pedals. If not, then darlington...

[Will.mendil]

I cant remembrer why i got them. Especially so many but still.
Ok noon time out: -what's jelly bean ( I thought it would have been a madbean schematic but I cannot find anything) - could you give examples of vintage pedals this could be used in? Just give a couple models and I'll do the research. Only "vintage pedal" is pretty vag. - when you speak Darlington. Do you mean I need to combine two of them to make a Darlington or that these transistors are Darlington ? ( if I understood what Darlington was )
Thanks again though

[LucifersTrip]

Only "vintage pedal" is pretty vag.

not "only"...I wrote "many" ...actually too many, form Fuzz Face to Fuzz Rite and way beyond

- when you speak Darlington. Do you mean I need to combine two of them to make a Darlington ?

exactly

[Will.mendil]

cool so jellybean (c'est quoi?) and you mean i could substitute "any" pnp transistor from vintage pedals and get a correct result 

[PRR]

> what's jelly bean

There are times/places where you need "the perfect part". Straight-grain Cherry for a fine hand-rail. Hoosier tires for your circle-track racer. Ge transistor from May 1957 with hFE==65.4.

And there's work that only needs "jellybeans". I have a rough wood floor with holes, I use any old scrapwood to make plugs (actual jellybean plugs don't last). Many well-designed audio stages can use "any" transistor that is the right polarity and doesn't suck.

I used to buy foot-square military surplus PCBs and torch the transistors off. Often I didn't know the specs, but I could tell NPN from PNP and used them like jellybeans.

[LucifersTrip]

and you mean i could substitute "any" pnp transistor from vintage pedals and get a correct result 

in "many" vintage pedals if the hfe is at least 80-100+ hfe and some a bit lower (but rarely lower than 50-60).  instead of asking in generalities, you are allowed to ask about a specific pedal here. simply ask about the exact pedal you want to screw with and someone will make a suggestion.   you really just have to breadboard the stuff and hear for yourself.

[Will.mendil]

I found on geofex a way of making a hfe/ leakage measuring device so I'll check ( my Dmm does not have the plug) and I'll see.
I don't really know what to build with. As I say I got 100s.
Mate I'll start with a tonebender. But if you guys have an idea of a rare exotic/uncommon  pedal I could try out with this. I'd rather. Tonebender seams plain

[armdnrdy]

You won't be measuring leakage from the 2N6520.....they are silicon transistors. 

[Will.mendil]

Oh ok I thought it applied to both. Well I least I can get the hfe

[Will.mendil]

Do you think this will work on silicon ? If you don't get leakage. The maths might be hard :p

[LucifersTrip]

it'll be easier since you don't have to subtract leakage...and will be accurate enough for the stuff we're doing

>>But if you guys have an idea of a rare exotic/uncommon  pedal I could try out with this

after you know the hfe

[Keppy]

Do you really need the test circuit? If there's no leakage to deal with, most DMMs can take HFE readings directly. Do you have little transistor sockets on the front of your meter?

[LucifersTrip]

Do you have little transistor sockets on the front of your meter?

Will.mendil : "my Dmm does not have the plug"

[Will.mendil]

For my defence it was late yesterday so I didn't see the (-) I thought it was (/) and dividing by zero bref...
Ok I'll do the circuit later today and see. Am I looking for low or high values?

[italianguy63]

I wrote a quick spreadsheet a few months ago-- you input your battery voltage, and the measured resistance of the 2 resistors.

Then, you input the two measured voltages (toggle on/toggle off), and it caluculates the Hfe and leakage.  When I get in Germanium testing mode, I just run it on a laptop along side when I am working.  It really speeds things along.

PM me with an e-mail address, and I will send it to you for anybody who wants it.

Mark

[Will.mendil]

here's the address. I do appreciate what you are doing. Could you include a quick schematic otherwise I am sure to run into issues.

I saw on the previous diagram that you need a specific resistor value 2.472 r or something like that. Is this compulsory? I mean as long as you measure the real voltage of the resistance boulder the maths work? :s

[Will.mendil]

I feel wired as a graduate in chemistry to ask this kind of "stupid" question