help!!alternative diodes

[jogina111]

Im planning on making a distortion pedal so I canvassed some stuff but some of the diodes are unavailable. Any suggestion on what diodes I can use instead of 1A34A and 2N3904?preferably the more common ones.

The schematic is on this site..

experimentalistsanonymous.com/diy/Schematics/Distortion%20Boost%20and%20Overdrive/Electra%20Distortion%20with%20volume%20control.gif

[Mike Burgundy]

2N3904 is a Si (silicon) NPN transistor. Any generic small signal Si NPN should work.
1N34A is a Ge (germanium) diode. This is used with a Si diode (1N4001) to get asymmetrical clipping. You can use any Si diode for symmetrical clipping, any Ge diode for asymmetrical clipping, or an LED for another flavor of asymmetrical clipping.
*edit*: if you happen to have some leaky Ge transistors or know someone who does you can use the BE junction as a diode. Leaky Ge transistors are useless for almost all applications, many people have bags of them with nothing to use them on, but they work fine as a diode. Experiment to your hearts content with the diodes.

[nocentelli]

Almost any common npn transistor and many diodes will *work* in the Electra, you'll get a slightly different sound, but it's not a parts-critical design. Most of Sean Lovepedal's amp-in-a-box pedals are just the Electra with slightly different components.

For transistors, you could try 2N2222 which are faily low gain, or 2N5088 which are a bit higher. For diodes, the germanium 1N34s can be tricky to get hold of: Several parts vendors advertise them, but send a different silicon schotky diode with the same part number in their place... Several builders have reported being caught by this in the past. 1N270s are another more common Ge diode, or just try out any old diode and see what you think: I've used bog-standard 1N4148s in an Electra which sounded fine.

[jogina111]

is it ok to use 2 leds for the diodes? What would it sound like..sorry, this is gonna be my 1st DIY.

[midwayfair]

is it ok to use 2 leds for the diodes? What would it sound like..sorry, this is gonna be my 1st DIY.

I recommend socketting the diodes if you're curious, or breadboard the pedal first. You will probably also want to socket the transistor. This is pretty good as first projects go, since you can play with the transistors, diodes, and input and output caps without hurting anything.

LEDs will be louder and will not clip very much.

If you want to try several different diodes, you can go to Tayda Electronics and order two each of the following:
1N34A (16c each)
1N60P (4c each)
1N914 (2c each)
1N4148 (1c each)
BAT41 (12c each)

Also, they have the 2N3904.

You'll spend like a dollar getting this stuff.

If you want some exotic diodes, I have some kits for sale over on Madbean's forum. Madbean also has a PCB for his Lavache, which is derived from the Electra Distortion and has a switch to give you a few different clipping options without opening up the pedal every time you want to hear something different.

[Mark Hammer]

is it ok to use 2 leds for the diodes? What would it sound like..sorry, this is gonna be my 1st DIY.

LEDs will "work" but since they have a higher clipping threshold, you won't get much audible clipping past the initial pick attack, unless you boost the signal feeding the circuit you are building.

The higher the forward voltage, the higher the ceiling, and only very tall peole will bump their head.  Silicon diodes have a lower forward voltage and ceiling.  germanium have an even lower forward voltage and ceiling, such that almost everything "bumps its head".

What is "best" depends on where you want most of your clipping to come from.  LEDs in the circuit won't produce as much clipping in the pedal, but since the output will be hotter, it will increase clipping in the amp.  Some folks like all the distortion to come from the pedal, some like it to come just from the amp, and some prefer varying combinations of the two.

[jogina111]

whats a leaky Ge transistor? How do I know if its leaky?

[Mike Burgundy]

All germanium transistors leak to a certain degree. It's inherent to the technology, and they age on the shelf too. This means there's a current through the transistor (Emitter to Collector) leaking through that is not controlled by the Base.
The base kind of works like the handle of a water tap. A small turn of the handle allows a big change in waterflow/current.
If a transistor leaks too much, the base will have limited control over the current through the transistor, bias will be off, it won't work as intended. A FuzzFace is a good example of a circuit that sounds best with germaniums but needs them to be relatively leak-free.
That circuit also prefers a certain gain-range, many transistors just aren't strong enough to get the preferred sound - these will also function very well as a diode.

[WGTP]

You can also use 2N7000/BS170 mosfets and J201/MPF102 Jfets.   

[Mike Burgundy]

Hooked up as diodes, yes. Let's make things even more complicated, Shottky diodes, zeners, whatnot ;P
Ignore all that and build the darned thing ;P

[jogina111]

shop says they only got 1N4001 to 4007 which has like 1v voltage drop...any ideas on how to do this?

[Mike Burgundy]

Stick in 2 1N4001's instead of a 4001 and 1N34a. That'll get you going, it'll work fine with those. Tinkering with diodes can always be picked up later.

[jogina111]

thanks mike...gonna try that...

Can 2 1N400n diodes in series make a low voltage drop like a germanium or cat whisker diode?

[Mike Burgundy]

putting the diodes in series will add their threshold voltages - they both drop say 0.7V so two in series will yield 1.4V.

[asatbluesboy]

whats a leaky Ge transistor? How do I know if its leaky?

Good read.

[jogina111]

would those "glass" diodes in mobile phone chargers do the work?