over stretched sk5?...

[Dj Task Manager]

Hiya,

Ive put the quad vcf mod in my sk5, pitch mod, and im trying to fit a pt2399 delay.  The problem im having is I cant seem to power it via the sk5 (Pluged in with its PSU).  I tried hooking it up to a point on the board that was reading 5v (the required amount for the pt2399). This didnt work so I put a 78L05 5v regulator in.  This also didnt get it going.  I tried hooking up the PT2399 delay with my bench supply (with the casio still running off of its PSU) and that seemed to work.  Is the problem there arent enough amps to go around with this added circuitry? Maybe the 78L05 isnt kicking out sufficent amps being run on 7.5v?  Any thoughts?

Cheers

Mike

[Circuitbenders]

Remember that it might still read +5v on your meter if it was a fast changing logic signal, as the meter wouldn't be fast enough to actually keep up with the changes.

Is there already a regulator in a SK5, i don't remember? If there is, and its a full size one then it should be able to supply up to an amp, which is way more than anything you could build and wire in could possibly pull, unless theres a bad short somewhere. If there is a regulator then source your 5v from its output pin, and source your ground from its ground pin. Alternatively you could use the ground and +ve rail of a nearby logic chip, which is probably running on 5v.

If the SK5 has one of those TO92 transistor case regulators like your 78L05, then i think they can only supply 100ma, which might prove a problem. I assume the PSU you're using is up to the job?

Try running the SK5 on 9v, it won't hurt it.

[Dj Task Manager]

thanks for the tips, ive found a spot near the power in that does just over 5v that works intermittently.  The pt2399 circuit works (made from the stock schematic from the datasheet), could it be that there is an error on my build though (a very slight short circuit (if such a thing exists!)) that means it requires more juice than it should?

Thanks again

Mike

[Dj Task Manager]

The solution came to me in a dream.  Its fixed and sounding like a beast now 

[Circuitbenders]

what was the problem?

[Dj Task Manager]

Well I think it was probably what I said about the voltage regulator not supplying enough amps.  So I just poked around near the power in and found a spot (next to the output amp) that does just over 5v's and sufficient amps.  A slight issue is I think this point dips a bit when the amp is doing its thing making the delay pitch warble a bit.  Quite cool but not ideal.  I'll try and resolve this properly at some point.  It does seem unusual that the delay is being so picky, I would hve thought it would run off most any stable 5v point.

Oddly I have discovered my PSU seems to outputting about 10v despite it being the stock 7.5v casio one!  weird.

My current problem is I cant seem to become a member of the sk yahoo group to access the instructions on the aliasing filter bypass mod.  (I want to implement this before fine tuning my filter bank.)

[Circuitbenders]

Oddly I have discovered my PSU seems to outputting about 10v despite it being the stock 7.5v casio one!  weird.

Unregulated power supplies always put out a higher voltage than whats stated if you're measuring it while its not being used. In theory it will only output 7.5v when its being run at the fulll milliamp rating written on the case, as the voltage of any unregulated supply will sag under load.

[ScissorFeind]

It will work if you run it on batteries because their potential current output is only limited by the battery capacity. It can be helpful sometimes to "test things under load."