What are your weekend projects?

[motterpaul]

Chris - your PCBs look truly amazing. It is not a process I have tried lately because I had no interest in making pedals that way. But when you want to mass-produce an effect of course it is the only way to go.

Yeah, I have been looking for ways to cut VERO. I can see using a table (miter) saw if it has enough teeth.  I tried small hand saws (no luck, you need LOT of teeth per inch). I also put a diamond cutter  on my drill press, but it was a too cumbersome (you do need clamps or something to stop it from moving around).   I could try my hand-held drill with the diamond cutter, but I think you need a very steady hand. But the dust is just "ack....!"

Last night I tried some titanium snippers (like heavy scissors but sharper) and those actually gave me a nice, clean cut.

My weekend project is further refining my MIII tonebender. Travis, thank you so much for the new layout to keep the tranny leads in order. I m getting some really great tones out of the AC125s I have.

Rocket - I tested more of my Batch V AC125s and I get hFEs in the 60 to 100 range, and leakage from .1 to .4 ma, but mostly at the low end of that. I think you need to try other batches (especially VI) to see how much these can actually vary. I think they are good trannies to collect a wide range - because you can find nearly any possible combination of hFE and leakage you want. (plus, the leakage doesn't seem to matter much in a lot of circuits).

[Chris60601]

motterpaul wrote

Chris - your PCBs look truly amazing. It is not a process I have tried lately because I had no interest in making pedals that way. But when you want to mass-produce an effect of course it is the only way to go.

Thanks for the kind words, Paul

When I do cut Vero, I prefer to use a Coping saw (see below)
This gives me the greatest control and pretty darned quick.
I sandwich the Vero between 2 1x2's  then inset into the bench vise.
After that, I file down and round off the corners.

[motterpaul]

I tried the coping saw, but I could only go one direction. I guess I need to look for finer teeth.

[Chris60601]

Hey Travis and Beaker, thanks  
In time I will certainly offer them up. I have a long way to go yet as I am making a good bit of mistakes along the way. When I get as good as some of the others here (Geri and Jonhk come to mind - There are others and the names escape me so please don't take offense).

But heck yeah - shortly

Cheers
Chris

[Travis]

Really glad that the layout was helpful to you Paul. I don't like twisting transistor legs either

The dust from FR-4 boards is toxic, so wear a dust mask if you're cutting or sanding that. The miter saw works great. Like I said you need to make a little "shoe" for the board to sit in like in my picture or that thing will take off and it will be dangerous. I'd hate to see one of you guys hurt your hands doing this.. Don't try unless you know how to do it safely. It's easy to do but very important to do it safely

[rocket88]

I score my vero with an xacto, then cut it with a blade cutter.  Smooth clean cuts.

Btw, paul trust me when I say I've tried many batches of AC125 as well as AC128, probably close to 6 unopened bags of 150 each, so that would be about 900 transistors for each type the to I've been through, so I have plenty of experience, there's a reason why I'm the emperor of the Ge deathstar. You are correct that they do sound good, but depends on what circuit. Some they can sound too trebley, others just meh. You have to know what to select the right transistor, it's not just the hfe. Ge builds really take more expertise then Si builds, where you can grab and throw a transistor in and it works great.

Leakage actually plays an important role in many circuits, even if it's not mentioned. Anything in the 400uA or higher is very leaky, and considers "bad" unless it's for certain circuits. The leakage has a role in the stability of the transistor, especially when it comes to how temperature affects it. The leakier it is the less stable the transistor.

There a great article about selecting transistors by R.G. Keen that dissects the fuzzface and talks about selecting transistors and what the leakage does/means. If you haven't read it yet you definitely should, make a lot of the Ge sorting and what to select make more sense.

[motterpaul]

Okay good. I did not see you say you had tried a VI batch. I sent some "VIs" to other people here and they got roughly the same HFE readings as I got. And that was before I had the DC175.

Before I had it I relied on the spreadsheet to calculate leakage - but I can't be sure how accurate that was. But I am sure about what I am getting now.

But FYI - here is a V that I just tried:

Test Result:
PNP Germanium BJT
Red-C Green-B Blue-E
HFE=110 at Ic=5.01mA
Vbe=0.273V at Ib=5.00mA
IcLeak=0.413mA

Here is another - but these are RARE:

Test Result:
PNP Germanium BJT
Red-E Green-B Blue-C
HFE=116 at Ic=5.01mA
Vbe=0.260V at Ib=5.00mA
IcLeak=0.472mA

[rocket88]

What's the temp in the room you're testing them? Are you letting them aclimate before testing?

[motterpaul]

Out of curiousity, to give us some context for your incredulity, what kinds of readings have you been getting on the different AC125uz batches??

We know they come in IV, V and VI - the stated verage range of HFEs on the different batches are:

IV - 50-100 hfe
V - 75-150 hfe
VI - 100-150 hfe

I have only done Vs and VIs, but I can tell you that you will get outliers. For me:

V hFE anywhere from 60 to 200 but with most in the 80 - 130 range. Leakage anywhere from 100 ua to 400+ ua, however ON AVERAGE (by far), most of them have been leakage 100ua to 200ua.

VI hFE anywhere from 68 to 218, but with most in the 120 to 180 range. Leakages anywhere from 100u to 400ua, but on average the leakages were from 200ua to 300ua.

The temp in my house is about 78-degrees constantly (I have central air running nearly full-blast, this is Arizona).

Once again, the info from DIYguitarpedals (from a post): Find it here: http://www.madbeanpedals.com/forum/index.php?topic=11715.0

Heres my special brand of understanding of all this germanium transistor mythos.  Probably full of holes?  Im no electronic engineer.  But here goes.

With the ac125 be careful which bin your buying from.  There are 3.  IV V and VI.  You have NO IDEA how long it took me to work that out!  I got a hold of the datasheet and can confirm these hfes:  

IV - 50-100 hfe
V - 75-150 hfe
VI - 100-150 hfe

With the ac125 the leakage is proportional.  So for say, a 50 hfe transistor you might get 80-120 leakage.  With 100 hfe, might be 200 leakage.  Some sellers show a photo of a V or IV bag, but send you something else.  I'm looking at you minifux... :o

So, if you get a VI bag, there all going to be very high hfe and leakage.  when you get around the 140 hfe mark, you start getting up to the upper limit.  Some will be 300-400ua which I reckon is fine.  Some will be over.

So, why cant you use over 300-400ua leakage?  Again, just my take on this.  Leakage doubles with every 10 degrees increase in temperature.  I take that as celius.  If so, at 20 degree (room temp), a 400ua leakage transistors is going to be 800ua at 30 degrees (hot room?).  40 degress its going to be 1.6ma.  That's getting up there.  40 degrees is getting pretty hot as well though, but its possible I guess.  My biggest concern would be run away leakage, I don't think you would get it at 400ua, but I usually try and keep them below 350 anyway (the ones I sell).  Run away leakage is where the current through the transistor heats it up, creating more leakage, more current, more heat.  Until the evitable.
What about tone with a leaky transistor?  I cant tell any difference.  Maybe a fuzz face or tone bender will misbias with a really leaky transistor in the hot sun?  One of the circuit designers around here could probably confirm that but i'm not 100%.  Otherwise they sound fine to me.  I have read a number of times, q3 in tonebender-esque circuits need leakage.  q1 and 2 doesn't matter so much.  I have to say, my Russian fuzz pedals do sound a bit different.  Not mind blowing though and I wouldn't spend too much time worrying about that.

One last thing about the ac125.  My sources (that's right I have 'sources') tell me the ac125 is in short supply.  I've got more then I will ever need so if you want some get them before they are gone.

Find it here: http://www.madbeanpedals.com/forum/index.php?topic=11715.0

[Travis]

Paul the data sheets aren't super accurate for hfe readings. In reality there won't be a huge difference between the numeral designations. You'll find plenty of transistors in the IV category that would fit in the VI category and vice versa. They're all the same transistors very loosely selected for hfe. So loose that there's no point in getting caught up in IV or V or VI. It all varies from batch to batch.

I'm sure most of us are already familiar with the specs since we have tons of those trannies already

[motterpaul]

"In reality there won't be a huge difference between the numeral designations. You'll find plenty of transistors in the IV category that would fit in the VI category and vice versa."

Yeah, I have to say that while you will find some, I noticed a distinct quantitative difference between V and VI. Honestly, I see some overlap, but those are the exceptions, not common.

Most in the V batches are much lower HFE on average. And while  you will see some in V camp with the same hFE as the VI, they will tend to have much higher leakages than the same hFE in the VI batch would have.

hey - the makers made these different batch numbers for a reason, I am just trying to discuss what it is. But it's all good. I was just trying to discuss the general differences in what you can expect if you buy either a IV, V or VI batch - no voodoo about it. Just a happy little discussion. There is a definite pattern.

I thought Rocket's idea to get the IV batch was brilliant since most of these circuits want lower Hfes.  All I could get was the V my second time (VI the first), and I just wanted to let people know that while the V HFes are lower, the leakage appears to be higher than you would expect. That tends to make me think the IV has lower hFEs and lower leakages.

Now - some circuits don't care. The Rangemaster seems to like high gain Ge just fine. The Tone Bender also - but that circuit also has a diode to keep trannies cool if they get too hot, it also doesn't care if you use Si for the Q1 & Q2 Darlington pair.

But I am just wondering why anyone is assuming my readings are off when I know what I am doing (it isn't brain surgery).

So I was just asking people to share the details of what they find between IV, V and VI - on average. I am mostly curious because I haven't tried IV.  

BTW: Have you seen the ToneBender Mark III I posted under your Yardbox contribution? I think that is a great sounding fuzz and I urge people to try it.

[rocket88]

Just to add to Travis, I don't know who your source is, but I regularly get factory sealed packages of 150 AC125uZ IV as well as AC125fz VI for $85 all day long. So I would be wary of your source if they're saying they're in short supply, just saying.

Also, you should not be getting that many with gains around 100-130hfe and leakage of 400uA, that's not good. Again, from my experience of sorting approx 900 AC125 VI, not counting the other multiple thousands of Ge transistors I've worked with. If you're selling them with damage that high, that's bad business, as that's not good for many circuits. Not come at you or anything, but I think you need to do a little more reading one gains and leakage especially in relation to Ge transistors. For instance you are measuring hfe, not hFE, or HFE, those are different things.

It's not to say that the leakage doubles with temp, but there is a major change. In some effects just using them for an extended time you will see a change in tone due to the change in temp from current flow. Leakage is bad for certain positions in certain circuits. If you haven't read Technology of a Fuzzface, it will explain nearly all.  For instance taken from the article in the link:

"How much leakage is too much? 100uA is common, 200 happens pretty often. More than 300uA means the device is suspicious, and more than 500uA I would say is bad."

So getting and selling transistors with leakage over 300uA really isn't right, unless it's for the right type of circuit. Not to mention, if R.G. says something it's worth listening and following. I've personally learned a lot from him, and if he says something about circuit design, he's right, and there's not debating it. Also, keep in mind he's forgotten more then many of us will ever learn. You listen to those with experience, and he is and EE, and had basically written the book/laid the ground work for all to us now.

To give you an idea of how leakage can affect the sound of an effect, it's been said that Greg Allman would put his fuzzes in a freezer to get then at the right temperature for the sound he wanted, and to get that sound through live gigs. Jimi Hendrix supposedly would do similar things with his, and make sure they were places in the shade during gigs, not to mention one of the reasons he changed form a Ge fuzzface to Si fuzzface.

[rocket88]

Side note paul, the rangemaster does care about hfe and leakage, but due to the bias network you can use a wide range of devices. It's in the R.G. article about the rangemaster.

Also, mNy of the AC transistors I have, that includes the different AC125's and AC128's none of them have leakage like the ones your have. Which model in specific did you get? Just AC125 or AC125Uz or AC125Fz? Ignoring the IV, V, and VI designation for this discussion, there is and will be a difference based on the exact model number.

The IV, V, VI designations are like the A, B, and C designations from Si transistors. If you get BC108's your will get a wide range of gains, where as BC108c's should be mostly higher gains. But remember, it's always a rough sort, as a result it's not as concrete as we would would like to think.

[motterpaul]

Once again, it seems as if I have to explain myself over & again here because people don't seem to realize that my comments are coming from a more informed place that I get credit for having.

Maybe that is my fault (I don't know, but my comments make sense to me, and I also never have this problem with people in any other forums).

But assuming it is my bad communication skills I will just say this and drop it.

1) ON AVERAGE - we all know that leakage in AC125s seems to be very relational to hFE, the higher the HFE, the higher the leakage (in general).

But I am saying that I am noticing that the PROPORTIONAL AVERAGES of leakage to hFE ratio in Batch V seems to be higher than in Batch VI. Proportional means that if I have one piece that reads 120 in batch V, its leakage tends to be higher than the same piece with the same hFE in batch VI. That is on average. But I am not saying I have a large number of very high leakage pieces - I don't - at all. But I had some. You didn't have any?

I noted that the few I have had are OUTLIERS (meaning they are the exception, not the norm).

But I also know that ON AVERAGE the hFEs are much higher in batch VI than in batch V - but for some reason I also cannot get anyone to agree or disagree with this statement, either. However, I am sure it is true based on what I am seeing. It is also what other people on the web say, like my friend at DIY Guitar Pedals

All I have asked is for you to post what you have found to be "average" hFEs and Leakage for batches IV, V and VI. I don't understand why I can't seem to get an answer to that simple question. I am also curious what "outliers" you may have found - like anything with leakage above 400u and what the hFE was - AND  which batches they came from.

These are not complicated questions, and this is really all I have been trying to ask all along.  

Thank you - no malice intended here at all - Also, there is no debate about Keen, I have read him, well over a year ago now and many times since. I know what he wrote, I get it and I agree, but it is not the topic I am asking about right now. Thanks.

[Travis]

I'm not sure exactly what's being debated here really. I don't think your readings seem off, Paul, but I do think much of the other info you posted isn't very accurate

Leakage isn't always proportional to hfe. It increases and decreases proportionally with temp change, but my lower hfe ac125 tend to be leakier than the higher hfe. That's one thing you don't seem to grasp, that your bag is not representative of all bags of ac125. Look at two bags of transistors, branded and labelled identically, but manufactured at different times, and you will see big differences.

It's difficult to make "absolute" statements about how these things test out because there are a lot of variables

I think you're just trying to help people with the info you've posted, but you may have tried to oversimplify the info to the point where it's a little inaccurate. Like that hfe and leakage doesn't matter that much, we all know that isn't true for most circuits

[motterpaul]

Travis,

I have been focused on AC125s, so I have also been pretty much been locked into circuits where leakage is hardly a factor (circuits I mentioned by name to be extra clear), but never did I say "it's never a factor" - that's putting words in my mouth and I really get tired of defending things I never said. I didn't even want to talk about how much leakage is a factor in other circuits. I wanted to talk about the differences in batches of AC125s.

Debating me on parts of my posts that were just a chit -chat (leakage as a factor in other circuits) is called a "strawman argument" - where someone uses a smaller point in a statement to refute the main point. It's just a waste for time for me and for people reading this because I never refuted you or argued that point, it wasn't germain to my post.

So, moving on...

You just said: "Leakage isn't always proportional to hfe. It increases and decreases proportionally with temp change, but my lower hfe ac125 tend to be leakier than the higher hfe. That's one thing you don't seem to grasp, that your bag is not representative of all bags of ac125. Look at two bags of transistors, branded and labelled identically, but manufactured at different times, and you will see big differences."

Funny -  I disagree with what you just said (verbatim) that "leakage is higher in lower hFE parts" - I do find it is "proportionately" higher, which is what I was saying all along; but in actual ua measurements leakage is higher in higher hfe AC125s.  So it appears to me you just verified exactly what I have been saying all along, while inferring I said something else.

Which makes me wonder if people actually read my posts, or just look for things to pull out and make arguments with me? But I did not come here to argue - let's just say "I get your point" and move on.

Now - that "temperature" thing where leakage doubles for every 10 degrees. That is in reference to Centigrade. My house is 26 degrees C (78 degrees F). To have it change by ten degrees Celsius my house would have to go to 96F (I would be calling the repairman). The point is that I guarantee you that if my room changes by even two degrees F I get up and reset the thermostat - summer weather is taken very seriously in Phoenix. My bags are acclimated and constant temperature. I am not touching the bodies - I have a DC175 - so I just find the inferences that I must be doing something wrong to be random and pre judgemental towards me.

So, let's let it go. I agree that more bad transistors will show up as they get more rare, but we are talking about NOS sealed bags. Unless these are counterfeit (which I really doubt) then there is no verifiable evidence to say I must have an odd batch - especially when no one else has bothered to report what I asked - what they found for average Hfes and leakage for their different IV, V VI batches.

Thanks for trying to help, anyway, sometimes you are very helpful, but this time was just one of those wash-out experiences for me.

[Travis]

Actually, if you made it to the second sentence of my comment you'll see that I'm not putting up a strawman argument at all. In fact I'm agreeing with your main point, and pointing out flaws in your smaller chit chat points. I don't see anything jumping out as flawed with your readings. The flaws are in your assessments and generalizations

[motterpaul]

Also - just to answer your questions more directly - there was never supposed to be a "debate" here. There was a question about the differences between IV, V and VI bags.

The point of the question was to figure out what is the norm for HFE and Leakage for each of those batches. I thought the question was perfectly clear.

The reason for the question, primarily, was to get more information to help a person choose which batch to buy, IV, V or VI, possibly for seeking the greatest number of pieces with a certain combination of HFE and leakage, because we all know that BOTH are factors, to varying degrees in different circuits. And we all know that in some circuits leakage is a crucial factor. Hence...

That was the point all along - I am sorry (but a bit unclear as to how) the point was missed.

[motterpaul]

Travis wrote

Actually, if you made it to the second sentence of my comment you'll see that I'm not putting up a strawman argument at all. In fact I'm agreeing with your main point, and pointing out flaws in your smaller chit chat points. I don't see anything jumping out as flawed with your readings. The flaws are in your assessments and generalizations

Good enough. I just thought the "refuting" of the smaller points, to the point where the larger point was never really answered, went more than a bit overboard.



moving on...

[Travis]

Ok Paul. I see your question perfectly clear now.

Here's the perfectly clear answer.

You can't expect a norm. These things vary a lot.


Edit: to add to that.. Just look at this discussion to see that you can't really establish a norm. Several of us have the same exact type of transistor with readings that are all over the place. You may buy 10 bags from one seller that are pretty consistent with eachother. Chances are this seller only has pieces from one or two different batches

Buy the same bag from a different batch and you've got different readings.

It's not gonna help to try an establish a norm, because that will always be broken. What we do is buy transistors, test them out, and then use them for their ideal application.

I bought several hundred Texas Instruments 2n404 from a seller on eBay. I got incredibly consistent (great) results for a while, then he sold all of that stock and his next batch of the same exact model was all testing ridiculously high hfe. Like averages 300+