Hello
For a long time I was collecting various layouts on J201. Now I decided to create a full-fledged effect. When designing, I noticed that I was not creating layouts correctly, I did not properly look at the datasheet and collected layouts, mixing the drain and the source.
I checked that when I replaced the correct position, the sound did not change and the bias did not move.
I heard that it is possible to replace the source and drain.
Is this correct and the circuit will work correctly or...

Hi,
I was trying to measuring transistors leakage and HFE by this method:
I have two problems:
1. first reading of voltage is highest, then voltage on multimeter is lowering. I don't know if first or last (after few minutes) reading is right.
2. Even if I get highest valu of voltege, HFE calculating by this method is a half of HFE that shows my multimeter.

What I am doing wrong?

So I randomly(stupidly) ordered some germanium transistors off Ebay, without doing research first. I now have a ton of MP37 transistors, which were super cheap, but they seem to be too low gain for anything I've built. They just don't have much in them. What should I do with these? Trash? I can't think of anything that they would work for. Any suggestions? They do look cool. Haha. :roll:

when measuring jfets for biasing do i need to take my meters impedance 10 meg into account and add that to the circuit

Mojo guys wont like it.... :slap:

but this is cool link (better than google search!!) :

Have fun!

Can you use a BC108-9 in a Dunlop Crybaby,or a Vox V847?

I decided to change the 8.2k collector resistor of Q2 for a 10k outboard pot. I like how it becomes spitty at lower bias voltages.
My question was if it was dangerous to fry a resistor if that pot went to extreme settings. I suppose the starving side is safe but on the other hand if the pot rotates to a 0k value will the transistor be damaged? If yes then I could put a 1k resistor in series to prevent that?

Hey guys,

I'm looking for a way to measure hfe on silicon NPN transistors (I don't have an HFE function on my DMM).

I've searched all over the web but only found ways to measure Germaniums which includes voltage leakage.

I did find this page:

Will the circuit on figure 1 work? He doesn't state the value of the resistor and what power supply should be used.

Any ideas?

Thanks

does any one have any idea if i buy 100 j201 smd are the odds good that i will get 6 to work will for the pinnacle or should i buy more

what does it mean a red dot on the transistors?? i have seen many dealers that says that their transistor have a red dot, but im not sure what ir means

hi, im almost sure that jummy used a sola sound tone bender MKII professional, but i have seen many different settings on this pedal, im building this pedal using the tonepad layout, and a set of US germanium transistor from small bear, gains are Q1 63, Q2 93, and Q3 124, i think these are grat for the pedal, got also the resistor set with a few changes on the original layout, now, here comes the deal, this its my first time with germanium transistors, so im not so sure, about specail care of...

Looking at some of these & the gains might be a in a usable range & possible a little high hfe 90-200 .Any one try them ?

last night i surfed the site and all of his hard to get transistors were gone...
he is out of stock on all of them ! :o
question is... has he been that before or is this the end ? :shock:

i just bought this one:

with free shipping :)

this seller has more pictures of same product, but higher price:

i will use it for testin hFE and ICEO on my transistors.

i hope it will do the job för circa 50 bucks only :)

this one was even cheaper but i dont know if it will do the ICEO :S :

i will come back with a short review...

Hi, i want to build a tone bender MARKII, with the BC109 metal case transistor, but im not sure if this transistor are biassed as normal silicon transistor or this are like the old schoold GE that are not consistent in the gains..

have anyone tried the smd version of the j201?? are they easier to bias??? or they are the same?? i want to get a lot of them to try them on the wampler plexi drive, its a bag of 25 but im not sure if thats enough to get 3 of them biased to 4.5-5v with the wampler schematic...

So I was playing around with slapping two transistors together to make a darlington and I have come across a really weird issue. For all transistors that I use, the darlington only behaves as it should when one or both transistors are put in upside down .

For instance, if I am using two NPN transistors: When both their collectors are facing upwards and connected to the load/resitor that is between them and the power rail - they don't conduct. Nothing gets through. However, when I flip one of...

Hey all,
I just recently got in a batch of some PNP Ge transistors (GT308B) from Moscow with the Hfe ranging from 39-59....
Any ideas on what I can use them for? I was hoping that their Hfe would be up around 80 or so to use them in some Fuzz Tonebenders and the like....are they any good still?

All suggestions welcome.

Hi,

I've got some silicon/npn/metal can 2N929 transistors that I bought 2 years ago, and that I really like the sound of.
I'd like to buy some more of them, but my supplier has ran out of them...

There's no company name printed on the transistor, but apart from 2N929 it also says M348 .

Anyone that know what transistor this might be?

As germanium transistors are getting more and more difficult to obtain, I know that I in a near future will try to emulate the sound/behaviour of Germanuim Fuzzes using silicon trannies (Impossible, I know - a silicon transistor will never be a germanuim one - but one must try ;-)

I've found this explanation to the phenomena of leakage:
... Transistor leakage is the leakage current across the reverse biased collector-base junction. This current then crosses the base-emitter, which, of...

Hi to all.

Here is a good topic to discuss about the quality of jfets.
The most commonly used in pedals is j201. BUT i red in this forum
that j201 is not the best one that should be used. They say that 201's are just easy found and used just because they are the standard.

so what other substitutes are there that can be used?
1. What fets are more naturally sounding?
2. What fets have more gain?

any thoughts or opinions? :D

Hey everyone,

I have been running some simulations of JFETs in order to study a bit about how to bias JFETs properly and also to teach myself along the way. I'm having problem with some of my calculations though. I am currently able to accurately calculate the operating point of a simple JFET circuit so long as it only has a source resistor. However, I've noticed that as soon as the drain resistor gets large enough to limit the current to be lower than the expected current draw for some source...