Torchy's GGG's BSIAB2 problems

[whitewave]

I'm planning to build BSIAB2 on veroboard, and Torchy's layout is what I choose.

I have some problems before starting building it:

R9 - is it an error? Do I have to waorry about where it is?

R13 - 4.7K.  Is it for led only?  So I can substitute it to match the Led I'm going to use. Is it right?

C1 and C6 are suggested as ceramic.  250pf and 150pF.  I can't find ceramic capcitors at Smallbear, but Silver Mica ones only.  Are they good substitute?
While other european shops I used doesn't seem to have 250pF caps, but 220 and 270.

R20 - linear on GGG and Audio on Torchy's.  What is it better to use?

C3a and C9 are non polarized caps.  I'm going to substitute them with alluminium electrolytics.

Thanks.

[MartyMart]

I think the "R9" is just a missing "number" from the schem, so Torchy
has used the same "numbering" system here ... no worries.
R13 is for the LED - so yes you can sub in whatever suits here, but for a
standard red 3mm  LED that should work fine.
If you can only find the 220pf - 270pf  thats close enough for "rock n roll"
Silver mica are very good quality but are BIG ! so you may need small
ceramics ti fit on the board !!
Linear is a different "taper" to log, so you will get a big volume increase
much earliers on the pots "travel" - I like 'em though so no probs  

Be carefull where you need "NP" caps you should use them, or buy some
non polar electro's .

Marty

[dosmun]

R20 is the Tone control.  Linear is the most common on Tone controls.

[whitewave]

Led - I'm not going to use a standard 3mm red one, but a 5mm blue one, so I have to substitute it.

250pF cap - Smallbear has 250pf Silvermica only, it seems that ceramic caps with that value don't exist.  I'll buy a 250pF Silver mica, a 220pF ceramic, a 270pF ceramic and a socket, so I'll try them.  Is it a good idea?

NP caps - Ok, I found them on Smallbear, i'm going to buy them.

Really thanks a lot.[/quote]

[MartyMart]

Led - I'm not going to use a standard 3mm red one, but a 5mm blue one, so I have to substitute it.

250pF cap - Smallbear has 250pf Silvermica only, it seems that ceramic caps with that value don't exist.  I'll buy a 250pF Silver mica, a 220pF ceramic, a 270pF ceramic and a socket, so I'll try them.  Is it a good idea?

NP caps - Ok, I found them on Smallbear, i'm going to buy them.

Really thanks a lot.

Your LED, if its an "Ultra bright" you can knock the resistor up quite a bit
it will still be "bright" but then wont eat your battery !
I use a 6k8 to a 10k for those ....
If you need 250pf but can only get a 270 ceramic, that will be fine  
The big silver mica's may well fit, if you bend the legs in a bit and they
don't touch any other components ... !!

Hope you enjoy the circuit, its a "KILLER" sound   :twisted:

Marty.

[pyrotek]

You can sub a 220pF or 270pF for the 250pF (C1). Since C1's function is a filter for unwanted RF signal that may slip into the circuit, it won't affect the whole circuit that much.

You can connect two polarized 0.47uF in series with positive-to-positive
(-)---||--+-+--||---(-) or negative-to-negative +---||--(-)-(-)--||---+ connection to get a NP cap. On my BSIAB2 I used a (C3a) 1uF polarized electrolytic cap and I have omitted the C3b.

[MartyMart]

You can sub a 220pF or 270pF for the 250pF (C1). Since C1's function is a filter for unwanted RF signal that may slip into the circuit, it won't affect the whole circuit that much.

You can connect two polarized 0.47uF in series with positive-to-positive
(-)---||--+-+--||---(-) or negative-to-negative +---||--(-)-(-)--||---+ connection to get a NP cap. On my BSIAB2 I used a (C3a) 1uF polarized electrolytic cap and I have omitted the C3b.

Yup but if you join two caps in "series" their value is "halved" !
So you'd have to join two 1ufs to get a 1uf value  
Two 0.47's in series will give you ..............0.47uf .....

Marty.

[ibanezts808]

Yup but if you join two caps in "series" their value is "halved" !
So you'd have to join two 1ufs to get a 1uf value  
Two 0.47's in series will give you ..............0.47uf .....

Marty.

lmao, that's good times.

[pyrotek]

ooopsss....  

Parrallel ->  Ct=C1+C2+C3+...+etc.
Series ->  1/Ct=1/C1+1/C2+1/C3+...+etc.

I forgot that one, you need two 2uF caps to get a 1uF NP.

Thanks Marty

[whitewave]

We're now a little off topic, but this post is really useful to me.

So to connect two, or more, electrolytic caps in series I have to solder +/+ and -/-, and I have as total value C tot = 1/C1 + 1/C2

while as for parallel connecting I have to solder +/- and +/-, and the total value would be C tot= C1+ C2

Is it right?

[MartyMart]

We're now a little off topic, but this post is really useful to me.

So to connect two, or more, electrolytic caps in series I have to solder +/+ and -/-, and I have as total value C tot = 1/C1 + 1/C2

while as for parallel connecting I have to solder +/- and +/-, and the total value would be C tot= C1+ C2

Is it right?

Series  "polarized" caps is     in > +> - +> -> out
Series "non polar" caps is     in > +> -> -> +  or reverse that whole thing .
The rest for values is correct  

Marty.

[Torchy]

Why do you call it "Torchy's GGG BSIAB2" ? I take my layouts from the schematics, not someone else's work. I didnt even look at the GGG BSIAB2 because I cant do pcb's ...... :?

[Torchy]

I'll qualify that (no edit button  :oops: )

I took the schematic from GGG, but didnt look at the project bits (ie layout, wiring etc).

If you wanted an explanation and/or help you could have pm'd me.

[whitewave]

If you wanted an explanation and/or help you could have pm'd me.

thanks a lot, but.. why?  We're enjoying a community with no commercial purposes, your layouts are famous to be very well made and GGG is a site so useful for everyone.  I bought a PCB from them, and I'll buy others in the future, but now I would like to try with veroboard and I asked for something that could be interesting for someone else.

Excuse me.