Circuitbenders Forum

Circuitbenders Forum => Circuitbending discussion => BENDING TIPS => Topic started by: wax+wire on July 27, 2013, 07:36:32 AM

Title: LTC 1799 and CASIO SK5
Post by: wax+wire on July 27, 2013, 07:36:32 AM

I've hooked my LTC1799 up to my casio SK5's 'brain' (a coil near where the tuning trim-pot is located), found the right pin on the coil, and cut the copper trace/PCB so that I can switch between the original clock source and the LTC.

I've found it to be both amazing, and unstable.  It doesn't work (though did once) on batteries, and will often crash or make more noisey sounds when using the powersupply and playing more than one note.

Is it possible the power getting to the chip isn't strong/consistent enough?  It needs 2.7v to 5.5v and I think (it is closed up at the moment), I was sending the IC around 3.4V.  Is there a good way to find a consistent and solid powerline for the IC?

Thanks heaps.  ps.  I'll post pics soon here and to the SK Yahoo Group for other benders!

Title: Re: LTC 1799 and CASIO SK5
Post by: Circuitbenders on July 30, 2013, 08:31:10 PM

Find the power pins for the IC's. Preferably any logic chips as they will probably be running on 5v. I suspect that anywhere in the SK5 that you're sourcing 3.4v is not remotely stable. It may only be reading 3.4v because its changing too fast for your meter to keep up, so its giving you an average.

An LTC1799 circuit can't produce a clock waveforrm with an amplitude bigger than the voltage its running on, and it needs to be stable, so source its power from the same power rail as the rest of the IC's in the circuit.

Title: Re: LTC 1799 and CASIO SK5
Post by: wax+wire on August 01, 2013, 07:08:52 AM

Thanks.

I found a much better power source, and the result is perfect, polyphonic pitch control!!!

That said, I like the unstable noise/crashes of the 3.4v supply, and might wire in a pot as a voltage starve/power crash option on the LTC.

I've uploaded images and annotations over at the Casio Yahoo Group for those interested