Madbean Collosalus Capacitor Question

Started by dfx_pedalpcbs, December 26, 2020, 07:33:37 PM

Previous topic - Next topic

dfx_pedalpcbs

Im looking near the sweep section of the 117 flanger clone by madbean, Does C13 & 14 have to be 15uf, can they be any other value? What effect do they have on the sound?
Thanks


njkmonty


11-90-an

#2
Quote from: njkmonty on December 26, 2020, 09:24:06 PM
arent they they speed caps?

Yes they are... since they are in parallel series they hav an equivalent value which would be 7.5uF which seems to be a less common value... you could get away with using a 10uF and a 33uF capacitor (which will give you around 7.6uF) instead of the 2 15uF's.

You can always change the value of the capacitor, just note the minimum and maximum speed of the LFO will change... smaller capacitor, faster speed, bigger cap, slower speed. (I think)
flip flop flip flop flip

GGBB

They are in series not parallel - and opposite polarity. This combination is bi-polar - 7.5µF. You can jumper one and use a bi-polar cap - 6.8µF is close if you can find one but that's far less common that a regular 15µF. As mentioned, 10 and 33 works but 33 might not be any easier to find than 15. Keep in mind that at 20% tolerance, 7.5 becomes anything between 6 and 9. You could probably get by with a bi-polar 10µF if you don't mind losing some of the fastest settings (and gaining slower ones).
  • SUPPORTER

PRR

If they are significantly different (10u and 33u) the little one gets most of the voltage swing. Since the voltage here *reverses*, this may be a significant reverse-polarity on the smaller cap, and maybe shorter life. Not that the cost of 10uFd will kill you, but Murphy says it will fail at a Bad Time.
  • SUPPORTER

11-90-an

Quote from: GGBB on December 26, 2020, 11:54:27 PM
They are in series not parallel - and opposite polarity.

oops... forgot my terms.. my bad   :icon_eek:
flip flop flip flop flip

Rob Strand

#6
Testing mad bean capacitors, 43  beans in every micro-Farad.





Using 4.7uF + 10uF paralleled polars on each side is a straight forward way to use off the shelf parts - despite using a lot of caps. 

Plenty of combinations of *parallel* *bipolars* can nudge up to 7.5uF,  6.8uF + 680nF   or  even 6.8uF + 1uF many other close combos.
Send:     . .- .-. - .... / - --- / --. --- .-. -
According to the water analogy of electricity, transistor leakage is caused by holes.

duck_arse

Quote from: Rob Strand on December 27, 2020, 03:11:13 AM
Testing mad bean capacitors, 43  beans in every micro-Farad.




but Rob, you have the wires connected and the plunger DOWN. what happens when you pull the plunger up?

Quote
Using 4.7uF + 10uF paralleled polars on each side is a straight forward way to use off the shelf parts - despite using a lot of caps. 

Plenty of combinations of *parallel* *bipolars* can nudge up to 7.5uF,  6.8uF + 680nF   or  even 6.8uF + 1uF many other close combos.

easiest would be to use a 6u8 [bipolar] hard wired with another 6u8 [again bipolar] switched parallel - get faster and slower, with band spreading.
" I will say no more "

iainpunk

QuoteTesting mad bean capacitors, 43  beans in every micro-Farad.
nice to know, if i'm ever out of coffee, ill crush some capacitors.

a big @ss resistor to ground in between those two caps keeps them alive longer. around 10M should be nice.

cheers, Iain
friendly reminder: all holes are positive and have negative weight, despite not being there.

cheers

anotherjim

I think if you used a 10uF pair and upped R22 to 10k, you'd still get a decent range of speeds.

Rob Strand

Quotebut Rob, you have the wires connected and the plunger DOWN. what happens when you pull the plunger up?
It's one of those press shots - always something wrong.
Send:     . .- .-. - .... / - --- / --. --- .-. -
According to the water analogy of electricity, transistor leakage is caused by holes.