How anal to be about components?

[dlazzarini]

I totally hear you! I've had a few caps that were outside of their marked tolerance (which was a little disconcerting) but I think those were in that 20% range that is definitely pretty wide at times. 1% or even 5% I'll probably not sweat too much, but those 10% or more might need a double check for sure. Good call.
Which transistors are you trying to measure? There are a couple of quick and easy schematics you can build with some components and a 9v battery that are out there I could dig up if you need!

Nothing in particular at the moment. I was just stating that that was the only component besides IC’s that I don’t know how to test. I’m still in the greenhorn stage. I’d be interested in seeing this circuits you speak of. I’m on a mission to figure out what all of this stuff does together and how it all works. Starting to breadboard etc.

 

[Crookedtooth]

Nothing in particular at the moment. I was just stating that that was the only component besides IC’s that I don’t know how to test. I’m still in the greenhorn stage. I’d be interested in seeing this circuits you speak of. I’m on a mission to figure out what all of this stuff does together and how it all works. Starting to breadboard etc.

Very much in the same boat! I'm actually in the midst of learning everything germanium, so here's where I started a few weeks back!
Test PNP Germaniums: http://www.geofex.com/article_folders/ffselect.htm
Another PNP Germanium test: http://tagboardeffects.blogspot.com/2012/08/germanium-transistor-tester.html
Other Fuzz Face FAQs: http://diy.smallbearelec.com/HowTos/FuzzFaceFAQ/FFFAQ.htm

Also, this JFET matcher is sweet: JFET Matcher: http://tagboardeffects.blogspot.com/2012/07/greatly-improved-jfet-matcher.html

 

[untamedfrontier]

Looks like I just got some homework

 

[radioteacher]

I test most resistors, capacitors, diodes and transistors before install. These are small builds and I have the time. Plus, my eyes are much older and weaker now. Most of my in stock parts are anywhere from 15 to 35 years old. I have to buy a few parts to build the units but not many.

I have a number of Ferrite Toriod cores. It would be fun to have a kit that I could wind the inductor. Maybe a Wah-Pedal.

It is fun getting into kit building again.

Thanks PedalPCB.com,

RT

 

[Chuck D. Bones]

I have a number of Ferrite Toroid cores. It would be fun to have a kit that I could wind the inductor. Maybe a Wah-Pedal.

I have wound plenty of toroid inductors and you definitely want to measure them. Takes a lotta turns to get up to 500mH and you don't want to have to depend on counting the turns. My first wah has a hand-wound 500mH MPP toroid inductor.

 

[Chuck D. Bones]

I always check NOS transistors and Ge diodes before installation. I usually trust my eyes with resistors, but if I'm unsure, the DVM is close by. Occasionally I'll spot-check parts just for fun. As PedalPCB said, tolerance is not critical in 99% of pedal circuits, octave-up being the exception where good balance yields a stronger octave tone. We use metal film resistors because they are low-noise, not be cause they are tight-tolerance. Remember the EHX rule: if you run out of something, grab whetever you have that's in the ballpark and install it. You think they built that many variations of the BMP on purpose?

I guess I've been lucky, no mis-marked or out-of-spec parts from DigiKey, Mouser, Arrow, SB or Tayda. ?

How many of you test your ICs before installing them? Yeah, that's what I thought. Too hard to do, so I don't either. Even OCD has its limits.

 

[BurntFingers]

Not only ehx. It's everyone. When I went to change the filter caps in a Laney amp I discovered about a third of the components were different to the schematic. I emailed them asking whether I should replace with the values on the schematic or the same as the ones already in the amp. They told me to use the schematic values, they just built them with "whatever was on the shelf" to get them out the door.

 

[Nostradoomus]

I test ICs once in a blue moon if I think something is up. It helps to have a drawer full of unboxed circuits with sockets on them

 

[soothsayer86]

I always check NOS transistors and Ge diodes before installation. I usually trust my eyes with resistors, but if I'm unsure, the DVM is close by. Occasionally I'll spot-check parts just for fun. As PedalPCB said, tolerance is not critical in 99% of pedal circuits, octave-up being the exception where good balance yields a stronger octave tone. We use metal film resistors because they are low-noise, not be cause they are tight-tolerance. Remember the EHX rule: if you run out of something, grab whetever you have that's in the ballpark and install it. You think they built that many variations of the BMP on purpose?

I guess I've been lucky, no mis-marked or out-of-spec parts from DigiKey, Mouser, Arrow, SB or Tayda. ?

How many of you test your ICs before installing them? Yeah, that's what I thought. Too hard to do, so I don't either. Even OCD has its limits.

Just got my first mismarked parts from Tayda. Some 1n4001s in a bag labeled 1n5817... good thing I know the difference visually and caught it immediately. I am definitely going to be on the lookout from now on though.

 

[Gordo]

Doesn't happen often but is a PITA when it does. Glad you caught it before soldering any in.

 

[2204Stuff]

I measure everything! even this post ~ thread, how far my face is from the monitor.............

 

[Chas Grant]

I spot check components to verify the bag and components match. Then put them in their place in the parts bin. I don't measure each part as it goes on, I like that I can build 2 pedals with the exact same parts, but that each have their own sound. Kinda gives them a life of their own. Now I will measure hfe if the circuit requires certain hfe's for a transistor.

 

[Crookedtooth]

Glad to see this thread is alive and kicking!
In the midst of building a few pedals with 2n3904's, measured out a few and whew! that is some variance! I find it interesting that this can shift so much - any thoughts?
Also, is there a way you figure out which is the best suited hfe for these? Either according to the original specs or by looking at the circuit? Or is it just a matter of taste?
Also also *wink* - When using these in something like the Master Fuzz - should all the hfe's be around the same number, or can they go from Q1-Q4 ascending, or can they completely mix and match?
Curious what your methods are and processes! - Might move this to another thread but it kind of falls under the "How Anal To Be" category...right?
Cheers ya'll!

 

[Chuck D. Bones]

Some people obsess about HFE and in most cases, if it's above 100 it just doesn't matter. With germanium transistors, leakage is more important than HFE. A few circuits are sensitive to HFE. Testing or analysis will tell you which ones. Example: I just built a Tube Bender and in that circuit, the only transistor parameters of any consequence are Q1 HFE the Vbe matching on Q3 and Q4.

 

[jubal81]

I'll chip in that I agree with what's already been said about passives in low-voltage pedals - if the value is in the ballpark, you're not going to hear a difference whether it's a $4 Sozo or a 4-cent greenie.

There are a few things I can get picky about, though:

Germanium diodes: They're a LONG way from 'ideal diodes.' Use a DMM to measure the reverse resistance across them. If it's less than at least a few Mohms, you need to account for that in your circuit. Just to note, though, that if they're hard clippers after an opamp like in a klone, it's less of an issue in that position. Big reason why some people swapping them out as clippers characterize them as being either 'bassy' or 'thin' - they're contributing to the RC filter.

Si Transistors: Low-noise designated trannies are, well, less noisy in high-gain circuits. A Muff with BC550 or 2N5089, for example, will be noticeably less hissy but give you the same distortion.

OpAmps: Low-noise, rail-to-rail audio opamps are less hissy and have more headroom (TL072 is NOT one of these). To my ears, ancient opamps don't add mojo -- just noise. And maybe offset voltages.

 

[Chuck D. Bones]

Well said.
I think the only bad thing about TL072s are they don't go rail-to-rail. In some circuits, it just doesn't matter. You can always get more headroom with higher rail voltage.

Good comment on Ge diode leakage. I wonder how many people built BMPs with Ge diodes only to be disappointed in the performance because the leakage was too high.

 

[Pimpoftheyear70]

I too measure all components before installation .
The extra time upfront saves you time trying to diagnose a problem later after you box it .
I have caught several " Wrong " values a time or two ... worth it imo .

 

[tcpoint]

I just check the color codes on the resistors (it doesn't take long to memorize the colors). I double check the label on the caps. I, usually, only measure critical transistors and diodes. I still mess things up every once in awhile but I doubt that measuring would stop me from being a bonehead.

 

[Dali]

I'm just happy that the pedal works... And I'm 99% stocking from Tayda.

Works for me

 

[p_wats]

I've been doing more pre-measuring of resistors, as that's bitten me a few times, but otherwise I've been lucky to have good components etc. (mostly Tayda as well).