Bright, pretty robustly functioned keyboard. I love the drum pads, but can't see myself using more than a handful or two of the 100 tones in the bank. I poked around briefly but didn't find anything very reliable or awesome, but there's got to be something kicking around here, at least a pitching bend or some distortion. If I can get some distorted low frequency playability out of these keys, then I'll put on some strap pegs as well, for live usage.
I know Casios are classics, but I've heard very little about the Casio SA-21, though it has similarities to someo f the others SA series.
(http://photos-d.ak.fbcdn.net/photos-ak-snc1/v1909/92/97/572677266/n572677266_1616715_9815.jpg)
(http://photos-e.ak.fbcdn.net/photos-ak-snc1/v1909/92/97/572677266/n572677266_1616716_25.jpg)
Try the voltage drop with this guy. There's details over in the SA-1 thread.
Voltage drop only works with batteries on this one, I was unable to find a point on teh board that would get the voltage drop to work with a DC adapter. I may have pictures from back when I modded mine, I'll have a look for you at some point.
That'd be awesome.
Quote from: Signal:Noise on December 21, 2008, 01:54:50 PM
Voltage drop only works with batteries on this one, I was unable to find a point on teh board that would get the voltage drop to work with a DC adapter. I may have pictures from back when I modded mine, I'll have a look for you at some point.
One would assume that you'd need to put a resistor in series with the output of the voltage regulator, otherwise the regulator will... regulate ;-)
Quote from: Signal:Noise on December 21, 2008, 01:54:50 PM
Voltage drop only works with batteries on this one, I was unable to find a point on teh board that would get the voltage drop to work with a DC adapter. I may have pictures from back when I modded mine, I'll have a look for you at some point.
That's cool, I plan to stay batteried. But could you direct me as to the bends you found on this? It's hard finding info on this guy, he's not a very popular SA keyboard it seems.
Tried a 1k pot for the voltage drop, but it didn't work. I don't think I'll be able to obtain a lower value pot, so how would I obtain 100 ohms of resistance by throwing some resistors in parallel. I don't know how to calculate that.
I'm still wondering about this keyboard, as none of the other SA series info I read -- regarding other models -- is useful for this keyboard. And I have not found a great pitch bend or distortion yet. The voltage drop should be easy, just not sure what kind of resistor to get: supposedly pretty low value, but I'd hate to buy another pack of another value, and it be useless. 200 Ohm, if I remember right. It's hard for me to even find that value of pot, so how do I calculate what statics I need to put in parallel to achieve such minute resistance?
I have an SA-21 waiting for me to open her up, quite interested to see what i can find.
What i generally do for power crashes is set up a potential divider, i find its a lot more stable and you can set a lower voltage limit rather than taking it all the way to zero. heres a good page on setting one up http://www.beavisaudio.com/Projects/DBS/
Granted, that page is telling you how to set one up for FX pedals, but its easy to apply it here as well.
Thanks for the great link!
Yeah amn, the guy who runs that site has some amazing projects and ideas on there.
K, maybe I'll give that a shot. What values would you recommend using to better suit a small Casio like the SA-21?
Off the top of my head, i cant remember what voltage the SA-21 runs on, 6 i think :)
generally what i've found with power crashes on the lower SA's is that you get the best crashes when the voltage drops by only a few volts, say 3. You get a good range then and lots of play.
+6V__
|
|
VR 1KΩ
|
-------------------∧
| |
1KΩ Take the power for the circuit from between these two points
| |
| |
0V------------------------v
(does that make sense? :-\ )
This set up will drop it to 3 volts, if you find that this is too much, exchange the 1K fixed resistor with a 2.2K. This'll bring it up to about 4.12V
Play around with combinations until you get something that works.
Dude, I got those parts on hand and gonna try it tonight. The SA-21 is actually 7.5V, which means your diagram might give me even more control. Either way, I'm amazed I can get such control out of 2 1k ohm components.
Haha. thats true, i dont know why i thought it was 6v :D
But if you replace the fixed resistor with a 4K7 resistor it'll only drop to about 6.1v which should be fine. If you left it as it was then you'd be dropping to about 3.75v, which is a bit too much of a drop.
I tried the 1k pot w/ 1k fixed and I still didn't have enough control to tune into CRASH mode.
If by 4k7, you mean 4.7k pot, then I'm gonna try a 5kohm fixed resister to see if it works.
Apparently 470 ohms crashes the machine nicely, but I can't find that low of a value locally, unless i want to pay $10. It's bunk.
Do you know Ohm's Law? I'm sure you can work out a solution to your problem...
QuoteIf by 4k7, you mean 4.7k pot, then I'm gonna try a 5kohm fixed resister to see if it works.
i do indeed, they're one and the same.
QuoteDo you know Ohm's Law? I'm sure you can work out a solution to your problem...
True, here's a reference calculator for you http://www.the12volt.com/ohm/page2.asp (http://www.the12volt.com/ohm/page2.asp) & i recommend you have a little play around with this free program http://www.yenka.com/en/Yenka_Electronics/ (http://www.yenka.com/en/Yenka_Electronics/)
Hope they help ;)