Component C29 is backwards on all TB-303's... (more inside)

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antto
 
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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by antto »

my audio device is also integrated into the motherboard

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computer controlled
 
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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by computer controlled »

So last night i decided to put this in backwards, and what do ya know, it made a difference in the resonance. still not quite there in regards to the 303's resonance, but much closer than it was before.

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altitude
 
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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by altitude »

Computer Controlled wrote:So last night i decided to put this in backwards, and what do ya know, it made a difference in the resonance. still not quite there in regards to the 303's resonance, but much closer than it was before.
try using it right side up but with a 33K resistor across it

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computer controlled
 
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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by computer controlled »

Will this throw it in self oscillation?

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antto
 
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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by antto »

Altitude wrote:
Computer Controlled wrote:So last night i decided to put this in backwards, and what do ya know, it made a difference in the resonance. still not quite there in regards to the 303's resonance, but much closer than it was before.
try using it right side up but with a 33K resistor across it
"right side up" you mean like per the x0x schematic (original) or reversed (as in 303) ?
and a 33K resistor in parallel with C29 ?

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altitude
 
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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by altitude »

exactly like the schematic but with a 33k across the + and - of C29 like don suggested. This gave me results almost identical to Brian's tests..

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computer controlled
 
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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by computer controlled »

I'll have to dig around and see if I have a 33k resistor laying around.

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altitude
 
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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by altitude »

anything close. I actually use a 100k in mine. The higher the resistance, the less it will knock down the peak

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computer controlled
 
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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by computer controlled »

I don't have any, but it looks like they have some at Rat Shack. How much of a difference would it make to keep the cap reversed and throw the resistor across it? I probably should have socketed it.

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altitude
 
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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by altitude »

Computer Controlled wrote:I don't have any, but it looks like they have some at Rat Shack. How much of a difference would it make to keep the cap reversed and throw the resistor across it? I probably should have socketed it.

Huge difference. I have a modern cap in mine and when I reversed it, there was very little change. When I switched it back to stock and added a resistor. the difference was dramatic. If you just want to try this, just solder 3 10Ks in series

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computer controlled
 
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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by computer controlled »

Well, i got a 22k and a 10k to make the 33k. Put the cap back to it's original position and put the resistors across C29. It sounds dirty and well, not good. Almost like there's noise being introduced into it now.

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computer controlled
 
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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by computer controlled »

BANNED, i think i might have killed C29. I reversed it again and took the resistors out. It sound even WORSE now =o] Now i gotta find another capacitor!

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computer controlled
 
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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by computer controlled »

And now it works fine... :roll:

No, it's still iffy. It gets all ugly for a few seconds when i let it sit for a bit, then calms down.

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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by computer controlled »

OK, is there a difference between 1uF and 1.0uF? Common sense tells me no. But i just wanna make sure.

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Re: Component C29 is backwards on all TB-303's... (more inside)

Post by Brassteacher »

Computer Controlled wrote:OK, is there a difference between 1uF and 1.0uF? Common sense tells me no. But i just wanna make sure.
You are correct.

What you may be hearing when the sound gets ugly for a few seconds then calms down is the cap building up enough charge so that it doesn't leak current severely.

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