[sdiy] problems going from breadbaord to pcb/solder

[Tom Wiltshire]

Doesn't sound like it's just the perfboard to me, it sounds like  
there's something genuinely wrong. Like David, I've never really seen  
anything that didn't work just because it was on a breadboard or  
perfboard, although I've often enough got lost in spaghetti on both  
of these.

Jay suggests that it could be the OTA gain control current. Could you  
sidestep the problem a little by increasing the LFO timing capacitor  
and the gain current? This would then make any offsets less  
significant, and might improve the reliability.

T.

On 15 Aug 2009, at 23:35, Dan Snazelle wrote:

>
> a friend of mine has been working on a vclfo partially based on
> the ray wilson VCLFO.
>
> it uses a triangle core with a lm13700, an integrator, and a tl072  
> comprator
>
> it worked without ANY problem on the breadboard
>
> however, when he soldered it up on perfboard the following problems  
> arose:
>
> 1. the symetry is off. mainly as the oscillator gets slower and  
> slower, the symmetry falls out of line. it is fine at higher speeds
>
> 2. at lower speeds, the oscillation dies. (at speeds which work on  
> the breadboard)
>
>
> I told him to try changing the hysteresis resistor value and cap on  
> the comparator and this DID help somewhat (it kept the osc from dying)
>
> however, things are still not quite right.
>
> IS THIS due to the difference between the capacitance on a  
> breadboard and the capacictance on a soldered board?
>
> or could it be something else?
>
> anyone have any ideas on how to save this?
>
> i am very interested in the results as I will soon be moving some  
> of my projects from breadboard
> to finished pcbs
>
>
> thanks so much
>
>
>
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