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Bazz Fuss; weird unwanted oscillations

PostPosted: 14 Mar 2012, 21:35
by fishfude
Hi guys,

I'm not a complete no0b when it comes to electronics, but I've been having a weird issue when trying to build the modest Bazz Fuss.

I've followed the http://home-wrecker.com/bazz.html version 1, and the http://www.seymourduncan.com/tonefiend/wp-content/uploads/DIY-Club-Project-2.pdf 'Bulk fuzz' schematics, but keep getting the same problem.

Well, i lie, I didn't have the 2n5088 transistor recommended. However I am using 2n3904 as suggested in the latter's notes.

The problem I'm getting is an unwanted low frequency oscillation (sometimes it's more like a gate), that is disrupting the distortion. Is it simply my choice of transistor that's causing this or am I doing something else wrong? I've tried various diodes including LEDs, 1n4001 and 1n4004. I have also tried using various transistors with similar failure (BC327, BC337,2n3096)

The best unaffected result, I got with a combination of 1n4001 and 2n3094. This still exhibited the problem at higher frequencies however.

Cheers

Re: Bazz Fuss; weird unwanted oscillations

PostPosted: 15 Mar 2012, 11:16
by Nocentelli
Hi, welcome to the forum.

I've made a number of Bazz Fuss and related circuits, but I've only ever used MPSA13 transistors and 1N4148 diodes (1N914 equivalent). I believe the diode in this case helps set the bias of the transistor, so this may be your problem (gating often seems to be related to misbiased transistors).

Re: Bazz Fuss; weird unwanted oscillations

PostPosted: 15 Mar 2012, 15:43
by fishfude
Thanks for the reply. i'll look into misbiased transistors.

FF

Re: Bazz Fuss; weird unwanted oscillations

PostPosted: 30 May 2012, 14:08
by Sonic
Are you using a battery or power supply? and how low is the humm, like a 50/60 Hz cykle? if you are using a power supply you need a diode or a a resistor and a capacitor to get rid of the ps humm.
Something like R1 and C1 in this circuit, would get rid of most of the noise.
Image

Re: Bazz Fuss; weird unwanted oscillations

PostPosted: 31 May 2012, 03:13
by CHEEZOR
I just built a couple of those with 2n5088s. I wanted to mention that this circuit is heavily gated even when done correctly. So Im not sure how much yours is gated, but it may be how it was intended to sound. I did not get any oscillations though. Play with the resistor value to change the bias. Also, if you upload some pics then someone might spot something that you have over looked. If you do post pics, be sure to include both sides of the pcb.