How easy is it to make an LFO on a keyboard?

bentoutofshape · June 25, 2011, 12:17:23 PM

...and what sort of equipment and parts do you guys think I will need?

Sorry if this question shows my lack of knowledge. I have just started and I was just wondering.

Bogus Noise · June 25, 2011, 08:05:15 PM

If it's pitched by a capacitor/resistor comination, then making an LFO is pretty straightforward to build up on a bit of stripboard. The Casper Electronics schematic works pretty well, though I like a 4.7k pot for shape instead of 10k.

http://www.casperelectronics.com/images/finishedpieces/speak-n-spell/Speak-n-Xbending/LFO%20schematic2.jpg

bentoutofshape · June 25, 2011, 10:58:12 PM

Hmmm I think I have just jumped in and sunk the deep end!

This may sound stupid guess, but, I'd guess every piece of gear that you are bending needs to have a different sort of set up and each one can be based on the idea of another.

Looking at that schematic you linked, I am getting what is going on and the pieces that are needed, I am just not understanding how both pictures correspond and, well

even where to start. Is there only one power source?

Thanks for the link by the way. It has opened me up to more ideas just looking at it.

Circuitbenders · June 26, 2011, 12:07:45 AM

Theres loads of different ways of making LFO's, which method you use and how you apply it to the circuit in question will depend a lot on what you're trying to install it on. Its not that hard but its not the most basic stuff.

What keyboard is it?

Bogus Noise · June 26, 2011, 01:05:34 PM

Quote from: bentoutofshape on June 25, 2011, 10:58:12 PM
Hmmm I think I have just jumped in and sunk the deep end!

This may sound stupid guess, but, I'd guess every piece of gear that you are bending needs to have a different sort of set up and each one can be based on the idea of another.

Nah, that's not stupid at all! Each device is a little bit different (except for the ones that are the same circuit inside a different case), but with each one you do you learn a little bit more that you can then apply to the next one. Also if one's a little too complex at one point, you can put it down for a while, do something easier, and come come back to it a few months later with more experience. Just be careful you don't build up a massive pile of open and unfinished keyboards

If this is your first bend, might be worth waiting till you've completed a couple of devices before adding an LFO, but it's up to you.

Quote from: bentoutofshape on June 25, 2011, 10:58:12 PM
Looking at that schematic you linked, I am getting what is going on and the pieces that are needed, I am just not understanding how both pictures correspond and, well even where to start. Is there only one power source?

Thanks for the link by the way. It has opened me up to more ideas just looking at it.

Ignore the Speak and Spell on the right for the moment. The pictures on the left are the important ones. They both represent the same thing, but the lower one will probably be easier to follow. Write down the components you need from the schematic, and get a breadboard to plug them into as well. The A and B are the power points, and the C is the point you connect to the pitch resistor... think that should be everything you need to know!

bentoutofshape · June 26, 2011, 02:09:22 PM

Quote from: Circuitbenders on June 26, 2011, 12:07:45 AM

What keyboard is it?

I have not really chosen one yet

I was just looking at the eBay auctions and seeking out one that would be cheap to try it on. I meant to ask which ones the forum's people would recommend I start with.

I have managed to get some good bends on my speak and spell, nothing to amazing though. I am looking to get something that plays constant tones now.

Which keyboards would you suggest I start with?

bentoutofshape · June 26, 2011, 02:27:15 PM

Ignore the Speak and Spell on the right for the moment. The pictures on the left are the important ones. They both represent the same thing, but the lower one will probably be easier to follow. Write down the components you need from the schematic, and get a breadboard to plug them into as well. The A and B are the power points, and the C is the point you connect to the pitch resistor... think that should be everything you need to know!
[/quote]

Thanks. So this whole thing is to be made on something separate away from the device we want it to go on? okay

Is there any reason why there are two different kinds pictures for a resistor? Also, what are the numbers that are near the wires, on the rectangles showing? Sorry, I guess this is quite irritating for you

Dylan · June 26, 2011, 06:32:56 PM

Quote from: bentoutofshape on June 26, 2011, 02:27:15 PM
Is there any reason why there are two different kinds pictures for a resistor? Also, what are the numbers that are near the wires, on the rectangles showing? Sorry, I guess this is quite irritating for you

The picture on the bottom is just a sketch of what the circuit should look like all soldered up, the image above that is just a simple schematic diagram.

The numbers on the IC (Ignoring the "555") are the pin numbers from the IC.

I hope that helps.

bentoutofshape · June 27, 2011, 01:32:27 AM

Quote from: Dylan on June 26, 2011, 06:32:56 PM

The picture on the bottom is just a sketch of what the circuit should look like all soldered up, the image above that is just a simple schematic diagram.

The numbers on the IC (Ignoring the "555") are the pin numbers from the IC.

I hope that helps.
[/quote]

Thanks.What are the parts marked '555' (IC?) and '100nf'? I know the others

Dylan · June 27, 2011, 02:36:33 AM

Yeah the 555 is an IC, you can get them for really cheap. 100nf would be a capacitor.

bentoutofshape · June 27, 2011, 09:44:34 AM

Quote from: Dylan on June 27, 2011, 02:36:33 AM
Yeah the 555 is an IC, you can get them for really cheap. 100nf would be a capacitor.

Excellent! I take it these: http://www.rapidonline.com/Electronic-Components/Integrated-Circuits/Timers-Signal-Gens./555-Timer-ICs/67451/kw/555 are the fellas (ICs) I need to get. Which ones from the list below should I be looking to get?

And these are the right ones, also: http://www.rapidonline.com/Electronic-Components/Capacitors/Ceramic/Radial-multilayer-ceramic-capacitors/62498/kw/100nf

Sorry to ask all these mundune questions. If you know of some online info sources to read or guides I would happily read them. Thanks for the info so far!

Bogus Noise · June 27, 2011, 01:35:22 PM

The 555 at the top should do it. You definitely don't want SMD, they're much smaller and harder to work with.

For the caps, these will be good:

http://www.rapidonline.com/Electronic-Components/Capacitors/Radial-Electrolytic/105-deg-C-General-purpose-radial-electrolytic-capacitors/180812

Don't worry about the voltage, it just needs to be higher than the voltage you'll be powering the toy and LFO with. I usually go for 16v or 25v.

bentoutofshape · June 27, 2011, 02:43:06 PM

Quote from: Bogus Noise on June 27, 2011, 01:35:22 PM
The 555 at the top should do it. You definitely don't want SMD, they're much smaller and harder to work with.

For the caps, these will be good:

http://www.rapidonline.com/Electronic-Components/Capacitors/Radial-Electrolytic/105-deg-C-General-purpose-radial-electrolytic-capacitors/180812

Don't worry about the voltage, it just needs to be higher than the voltage you'll be powering the toy and LFO with. I usually go for 16v or 25v.

That's excellent!! I have most of the parts needed. I still have to work out how exactly to get it working on a selected keyboard and how to power it. My knowledge on such things is quite limited but I guess if I do not ask stupid questions I will never learn :/

Dylan · June 27, 2011, 03:20:55 PM

Don't worry about asking "stupd" questions. They're not stupid at all. It's smarter to ask. I've been circuit bending/making synths for years and I still have questions. I think most of us do

bentoutofshape · June 27, 2011, 05:29:59 PM

Quote from: Dylan on June 27, 2011, 03:20:55 PM
Don't worry about asking "stupd" questions. They're not stupid at all. It's smarter to ask. I've been circuit bending/making synths for years and I still have questions. I think most of us do

I guess my main stumbling block now would be application now. How would I go about putting such an LFO on a (for arguments sake) Casio SK1? The LFO's application would be on all the bends I have found so how do I get it attached? ..to any keyboard?