bandido II sensitivity

[mike]

Hello,
I have made a bandido on a small PCB 4cmx6cm with smd components.
I have a pretty good sensitivity. (a little better than a comercial one)
I have added a big capacitor 10000uF between the -5V signal and the ground to avoid the instability when the sensitivity is at its maximum !
I still have a small instability (beep beep with a regular rythme) and it doesn not look like noise. Then i think i can gain some more cm.

[Goodrat]

Re: bandido II sensitivity

Did a cap on the +5 help any?

[mike]

Re: bandido II sensitivity

no, because it is regulated by the 7805 regulator, then the voltage is stable.
The pb with the -3V supply is that when it beeps, it create a current peak in the comparators and then a voltage fallage. Then it creates an oscillation.

[Goodrat]

Re: bandido II sensitivity

On my Cutlass II that I converted to a Badido II, I had an oscillation when the disc was set to minimum. I traced it to the input to IC5B where I believe I tacked a 100K to ground to stop it. I wonder if the -3 cap would have fixed it.

[mike]

Re: bandido II sensitivity

i will try the 100k, ! it will avoid me a big capacitor

[Goodrat]

Different problem

The oscillation I had was not related to the chatter that results when turning up the sensitivity too high. It was a high frequency oscillation that appeared when the disc was at minimum. The effect was a few inches depth reduction at that full ccw disc setting and could only be seen with a scope.

[mike]

Re: Different problem

OK, it is different, My oscillations were at a low frequency (1Hz) , it can purhaps be improved with a 2.7V zener diode to force the negative voltage