rebote 2.5 + battery flat = Ear damage

[chromesphere]

Hi All,

I was playing around with my rebote today, and all of sudden, i started getting these VERY loud screeching oscillating noises from it.  I thought i'd broken it.  Came good for a bit, then started up again.  Long story short, i worked out, using a different battery it was ok.

So the question is...Am I going to get permanent ear damage, whenever the battery goes flat in this thing?  Is there anyway to stop this from happening?  The noise is almost on an 'unsafe' level...Absolutely ear piercing.

Anyone else had this happen before? Your help appreciated.

CS

[aziltz]

does it use a voltage regulator?  I thought those things just turn off if they don't have enough juice.

[chromesphere]

Hi Aziltz,

Yes it does actually, 5 volt positive regulator: 78L05.

Maybe the regulators playing up...well, ive got some spares.  Might try swapping it.  Start with that...

Thanks Aziltz!

[aziltz]

hope it helps.

[chromesphere]

Tried swapping over the regulator for a new one, didnt make much difference unfortunately.

Also tried swapping the PT2399, just for a stab in the dark.  Also didnt make any difference...

Thanks for your help anyway...

CS

[aziltz]

you know, it almost sounds like your getting runaway repeat oscillation at a high frequency.  Perhaps theres some low pass filter thats not quite soldered right?

[Processaurus]

Is your voltage regulator's input and output bypassed with .1 caps to ground (in addition to any big electolytics) as per the data sheet?  Without them regulators can freak out.

[chromesphere]

Hey thanks for the responses guys,

Ill double check over the boad and make sure its all up to scratch.

Its strange how it only happens when the battery starts to run out though...

Even when the battery isn't flat, I can get some crazy feedback if i turn up the repeats pot to about 90%.  It sort of builds up slowly, getting louder and louder.  I thought this was normal...? 

Oh hang on...I subbed the repeats pot for a 50k instead of 25k...

I think ill find the right part for this. Maybe thats whats causing all the problems...

CS

[blanik]

i think your Rebote works perfectly fine, mine does exactly the same thing but after using it with batteries for a long time i can almost predict when it's about to happen, the repeats become noticeably more noisy like 10-15 minutes before it happens (the Klon does the same thing), still the Rebote is one of the few delays you can use for a long while on a fresh battery you just need to unplug the pedal when not in use and anyway, it's true bypass so even if it happens while playing i just step on the switch on keep playing...

[chromesphere]

Ah-ha!  So it is normal!

Thanks Blanik! Ill listen out for the noisy repeats next time!

CS