### Author Topic: What matters - what doesn't  (Read 73316 times)

#### aron

##### What matters - what doesn't
« on: July 14, 2004, 03:25:40 PM »
Following up on R.G.'s excellent post, I'd like to start this thread so we can help the beginners on what matters/doesn't matter in regards to our low voltage effects.

Please post to this thread and it will be incorporated into the FAQ.

Of course these are all generalizations.

#### aron

##### What matters - what doesn't
« Reply #1 on: July 14, 2004, 03:28:14 PM »
We use 1/4 watt resistors, but in reality, you can use any type of resistor even if it's larger (i.e. 1/2 watt)) and the measurement doesn't fall totally out of range. (+- 5%). Provided you can fit them on the board.

#### aron

##### What matters - what doesn't
« Reply #2 on: July 14, 2004, 03:29:02 PM »
You can use film caps instead of electrolytics provided you can fit them on the board and they are the same value.

#### aron

##### What matters - what doesn't
« Reply #3 on: July 14, 2004, 03:30:24 PM »
If you don't have a specific value resistor or capacitor, you can string two or more of them together to get the desired value. If you can't find the exact resistor, one that is within 5% is OK unless the circuit calls  for extreme tolerance.

#### aron

##### What matters - what doesn't
« Reply #4 on: July 14, 2004, 03:32:22 PM »
If a schematic calls for a polarized capacitor (electrolytic, tantalum), you can substitute a non-polarized capacitor and it will work.

#### aron

##### What matters - what doesn't
« Reply #5 on: July 14, 2004, 03:34:33 PM »
If a circuit calls for a 16 volt 22uF capacitor, you can use any 22uF capacitor that has a voltage rating that is higher. For example a 24 volt 22uF capacitor. The same goes for film. You can use a 630V film capacitor in a 9 volt pedal.

#### aron

##### What matters - what doesn't
« Reply #6 on: July 14, 2004, 03:39:08 PM »
If a schematic has been built by many and is pretty much verified correct, and your build "doesn't work". Despite what you may think, you have made a mistake in your circuit or a component is bad. It's hard to accept, but it's true.

Usually the components that may be "bad" are transistors and ICs and  rarely resistors and capacitors.

#### petemoore

##### .
« Reply #7 on: July 14, 2004, 03:43:43 PM »
You can use a 10M [instead of 22M] before the input cap of a Micro Amp...does it make a difference?..I doubt you'd be able to tell, I used the 10M because it was there, could have built a 20M as there were two, opted for the 10M...
I used 22k's [instead of 10k's] for the voltage divider, because they were there, would I find it different?...I wouuld have to buy more resistors to find out.
I've been using 386's though for voltage dividers, I don't notice any difference when using them.
Pulldown resistors...do you need them? I use them when an effect pops during switching...there's the reason for these.
Power protection diodes, there is a reason for them, I often forego the pleasure, because I don't reverse battery polarity [knock on wood]...
Some things you can 'fudge' with no problems and no percieved difference...others have to be .. say within' the standard 10% tolerance for a circuit to work, or to work 'right'.
Most of the circuits around here have been gone over with a fairly fine tooth comb as far as what's possible and what's not possible, what mods do what, a simple question almost invariably gets a concise answer...just type about it and get feedback, or try it yourself to see...if you really need or want that...input buffer for instance.
Convention creates following, following creates convention.

#### phillip

##### What matters - what doesn't
« Reply #8 on: July 14, 2004, 04:21:52 PM »
Using Carbon Composition resistors in Fuzz Faces and other low voltage circuits for "vintage sound" or "brown sound" is pure marketing hype.  They add nothing to the sound other than NOISE...usually something like a "hiss."  For better results, use 5% Carbon Film resistors, and for best results, use 1% Metal Film resistors.

Phillip

#### Fret Wire

##### What matters - what doesn't
« Reply #9 on: July 14, 2004, 04:30:19 PM »
Always use sockets for IC's. It prevents heat damage (some are expensive), and allows for easy swapping.
Fret Wire
(Keyser Soze)

#### Paul Marossy

##### What matters - what doesn't
« Reply #10 on: July 14, 2004, 04:30:24 PM »
All grounds do not have to connect to the same point, but all grounds need to be connected together.

#### Ballz

##### What matters - what doesn't
« Reply #11 on: July 14, 2004, 04:30:35 PM »
Old germanium transistors cannot be tested properly with just the hfe range on your multimeter. You will need to test them according to the "How to select transistors....." documet over at Geofex (insert link here), or with a 1950:s transistor checker that is equipped for leakage testing.

#### Ballz

##### What matters - what doesn't
« Reply #12 on: July 14, 2004, 04:32:55 PM »
Always use a cooling device (flat pliers) when soldering a leg of a transistor - or use a transistor socket.

#### Fret Wire

##### What matters - what doesn't
« Reply #13 on: July 14, 2004, 04:34:18 PM »
Use sockets for capacitors and clipping diodes in circuits where changing them is how you dial in the amount of distortion or bass/treble response.
Fret Wire
(Keyser Soze)

#### Fret Wire

##### What matters - what doesn't
« Reply #14 on: July 14, 2004, 04:35:36 PM »
Never assume the pinout of a specific transistor is the same from one manufacturer to the next.
Fret Wire
(Keyser Soze)

#### Fret Wire

##### What matters - what doesn't
« Reply #15 on: July 14, 2004, 04:40:59 PM »
Tubescreamer fans: A twenty year old JRC4558D chip sounds no better than a new JRC4558D chip. Save your money, forget the mojo and hype, and buy the new chip. Truth is, there are better IC's out there for the TS-9/808: RC4558, RC4559, NE5532, TLO72, to name a few.
Fret Wire
(Keyser Soze)

#### Fret Wire

##### What matters - what doesn't
« Reply #16 on: July 14, 2004, 04:49:22 PM »
Always double check the polarity of components BEFORE you solder them in. Electrolytic caps, tantalum caps, diodes, and LED's.
Fret Wire
(Keyser Soze)

#### Arno van der Heijden

##### What matters - what doesn't
« Reply #17 on: July 14, 2004, 04:50:23 PM »
(Almost?) all dual opamps use the same pinout.
Makes for easy swapping and experimenting if you use a socket!!

#### Paul Marossy

##### What matters - what doesn't
« Reply #18 on: July 14, 2004, 04:54:42 PM »
Single opamps and dual opamps DO NOT have the same pinouts.

#### Fret Wire

##### What matters - what doesn't
« Reply #19 on: July 14, 2004, 04:54:44 PM »
Use a DMM to double check your resistor's value's just before you solder them in.
Fret Wire
(Keyser Soze)