smallsound/bigsound - mini  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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Post by smallsnd/bigsnd »

natron_mn wrote:Just discovered this awesome thread. I was going to attempt to build this little monster, but had a question first.

What is the minimum voltage on the 220uf cap? I have some of those cool low profile Lelon caps, but they are only rated 10V.

I'm not sure how to tell from a schematic what the voltage requirements are for a given component.
you should always use caps that are rated higher than the supply voltage - get some 16V caps to be safe. :thumbsup

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Post by natron_mn »

Thanks Brian!

Is the supply voltage just 9V? More generally, is the supply voltage for any pedal with a 9V power supply simply going to be 9V? Or, do voltages change within the pedal depending on the transistors/ICs?

In this schematic, it looks like there is only a diode and resistor between V+ and the 220uf resistor. So the diode is simply a circuit protection diode and won't change the voltage hitting the 220uf cap?

Sorry if this question is ig'nant. I'm wanting to learn how pedals function as opposed to just building premade pcbs with instructions (a la Madbean pcbs). Those are fun to build, but I'm not really learning anything other than how to solder and follow instructions!

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Post by natron_mn »

FYI, I picked up an actual SS/BS Mini, and that pedal just rips. So versatile! I still want to attempt building one, but now it's not as big of a rush since I have the real deal!

Way to crush this one, Brian!

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Post by natron_mn »

Anyone know if I can substitute the 1n5158 diode? Is it just a polarity protection? Could I use a 1n4001 instead?

I’ve never heard of the 5158 diode before. Only 5818

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Post by BetterOffShred »

Yeah toss a 4001 or a 5817 in there for sure. According to the schematic on page 1 of this thread it's just a polarity protection as suspected. :thumbsup

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Post by smallsnd/bigsnd »

natron_mn wrote:FYI, I picked up an actual SS/BS Mini, and that pedal just rips. So versatile! I still want to attempt building one, but now it's not as big of a rush since I have the real deal!

Way to crush this one, Brian!
thanks! :D
BetterOffShred wrote:Yeah toss a 4001 or a 5817 in there for sure. According to the schematic on page 1 of this thread it's just a polarity protection as suspected. :thumbsup
yeah i use 1n5818 for less of a voltage drop than a 1n4001. 5817 would be even less but really any of the above will be totally fine.

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Post by natron_mn »

Thanks you two! :hug:

I hope to get building this week and report back my findings

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Post by natron_mn »

About to start building this (finally).

I saw on the first page something about a scramble mod. Would you still happen to be able to share that, Brian? I know I should walk before I run and get the initial build up and running, but I can't help myself :)

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Post by tome.talevski »

Hello! Just built the ssbs mini and it’s sounds awesome ... ! .. except that I cant get the bias pot and trim to work properly. The lowest voltage on the 5457 drain I can muster is approx 5v via the trim.. the bias pot also only has a 2v range (max is 7v min is 5v). It’s making some difference although marginal... also, based on the tagboard thread, the bias pot range ought to be around 5v. ... so, any ideas as to why I can’t achieve a lower drain voltage?? Plus, how to broaden that pot range??

Cheers

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turbofeedus
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Post by turbofeedus »

tome.talevski wrote: 14 Oct 2020, 07:13 Hello! Just built the ssbs mini and it’s sounds awesome ... ! .. except that I cant get the bias pot and trim to work properly. The lowest voltage on the 5457 drain I can muster is approx 5v via the trim.. the bias pot also only has a 2v range (max is 7v min is 5v). It’s making some difference although marginal... also, based on the tagboard thread, the bias pot range ought to be around 5v. ... so, any ideas as to why I can’t achieve a lower drain voltage?? Plus, how to broaden that pot range??

Cheers
Where did you get your 2N5457? lots of fake JFETs on the market.

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Post by tome.talevski »

turbofeedus wrote: 16 Oct 2020, 05:00
tome.talevski wrote: 14 Oct 2020, 07:13 Hello! Just built the ssbs mini and it’s sounds awesome ... ! .. except that I cant get the bias pot and trim to work properly. The lowest voltage on the 5457 drain I can muster is approx 5v via the trim.. the bias pot also only has a 2v range (max is 7v min is 5v). It’s making some difference although marginal... also, based on the tagboard thread, the bias pot range ought to be around 5v. ... so, any ideas as to why I can’t achieve a lower drain voltage?? Plus, how to broaden that pot range??

Cheers
Where did you get your 2N5457? lots of fake JFETs on the market.
From pedalparts Australia.. typically reliable I think. I managed to resolve the issue by changing the 1k source resistor to 100ohms (in the debugging forum).

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turbofeedus
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Post by turbofeedus »

This article is a good read for anything regarding JFET amplification.
http://runoffgroove.com/fetzervalve.html

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