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Building Keith Raper's Circuit

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  • #76
    A quick question about the Keith Raper Circuit for piezo/switch. Rather than wire it into the drum, I'm interested to know if one can make up an external version. The beauty of this is that the circuit could simly be removed when moving to a different input or different module.
    So one end would have a stereo jack that would go into the drum where it meets the standard-wired dual piezo circuit. Thus, instead of being wired to a pole of each piezo, it would be connected to the jack. Is this possible and how would it be wired? Any thoughts?
    Edit: I've worked it out, but an not entirely satisfied with my build of the KR curcuit. It's not triggering the rim well, even though I can get the rim light to light up by flicking the piezo directly.
    Last edited by allanjohn; 03-16-08, 08:31 PM.
    Beater-tester. digitalDrummer
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    • #77
      Is resistor wattage value important?

      Originally posted by sae View Post
      R2: Resistor 2 - 1M (1 meg) resistor. I believe this is used to provide a voltage divider, so for this reason you can use a larger resistor if you wish (2 meg, etc)
      My local electronics shop carries 3 different 1 meg resistors.

      62.5mw - 0.1w - 1/4w

      Does wattage matter? If anyone could provide information on what they've used successfully, I'd sure appreciate it.
      Jack

      Sabre's Album

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      • #78
        I used a 0.25w and that seems to work...
        Beater-tester. digitalDrummer
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        • #79
          1/4 watt here too.

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          • #80
            Originally posted by Sabre View Post
            My local electronics shop carries 3 different 1 meg resistors.

            62.5mw - 0.1w - 1/4w

            Does wattage matter? If anyone could provide information on what they've used successfully, I'd sure appreciate it.
            Wattage for a resistor is the maximum power it can handle (dissipate as heat) before it burns up. Considering the low cost and availability 1/4 watt are an easy choice and will more than handle the very low power requirements. The smaller values you listed should be fine, too, but they start getting small to handle.

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            • #81
              Awesome, thanks guys!
              Jack

              Sabre's Album

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              • #82
                Some help building Circuit #1: 2 mono pads in stereo input of TD-6V (TOM1)

                Hello,

                I recently bought a TD-6V and decided to build Keith Raper’s circuit to connect two cymbals (a splash and a china) to a single stereo input (TOM1, for instance).

                I’m a total newbie in electronics but, after reading a lot of posts, I worked up the courage to go ahead and make the thing. To my enormous surprise, IT WORKED!!

                Although it does exhibit the problem described in post #34 (when I hit the “switch” pad softly, sometimes it triggers the sound of the other pad), I don’t think this will be a big deal when I use the box with 2 cymbals instead of pads.

                I’m sure that pretty much everyone here must have gotten their circuits to work like me, but in case anyone still needs a bit of help with the actual physical layout (what goes where), here is a diagram I made to help myself:

                http://personales.ya.com/mcbourdet/circuito_pads.jpg

                Diagram description:

                1- The grey horizontal lines represent the metal tracks on the board. If one uses a board without tracks, all the horizontal connections will have to be created using cables (much messier, IMHO).

                2- The black dots represent the cables that must be soldered. For example, the dot labeled “ST T” indicates a cable that goes from that hole in the board to the tip (ST Tip) of the stereo jack.

                3- The blue icons represent the electronic components. The TR1 transistor must be soldered with the orientation shown. The diodes are soldered with the orientation of the arrows.

                4- The red line (GND) just represents the track where all the ground cables are connected to each other.

                A few general comments:

                1) The material I used…

                - 1 board WITH copper tracks (e.g. http://img-europe.electrocomponents....C433832-01.jpg.
                - 1 1N4148 diode (0,7 V)
                - 1 Schottky (BAT46) diode
                - 1 100K (linear) potentiometer
                - 1 BC337 transistor
                - 2 1M resistances
                - 1 PVC box (DON’T BUY ONE TOO SMALL :-D)
                - 2 mono jacks
                - 1 stereo jack (e.g. http://ersonelectronica.com/images/645-4450.jpg)

                2) Components I left out…

                * I didn’t include the 10K R1 resistance. The 100K pot seems to work alright by itself (unless someone thinks different)

                * I didn’t include the lower BAT46 diode (I think it is used for Yamaha modules and mine is a TD-6V, as stated above).


                Well, I hope all this helps…

                Best wishes,

                Alex

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                • #83
                  Thanks for the great post alex! (pretty good for a first post I'd say )

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                  • #84
                    Thanks!

                    I just made a simplified version or the diagram where the cables are closest to their intended connectors and the wiring is slightly cleaner:

                    http://personales.ya.com/mcbourdet/c...ads_simple.jpg

                    The circuit is *identical* to the previous one, just a little easier to make.

                    Alex

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                    • #85
                      So I'm going to be making a three zone ride, and I'm trying to figure out how I'll need to wire things up. I've seen plenty about making dual zone crashes, and I think I understand how that works. From my understanding, in order to get edge\bow triggering and have the edge piezo chokable, I'll need to use the keith raper circuit, but to get bell triggering I'll also need to use another separate KR circuit since the bell piezo will act like a switch? or am I over complicating things?

                      -- Setup -- DIY -- Rock Band Converter --

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                      • #86
                        Make the edge / bow of the cymbal the same as a two zone, then use a single piezo for the bell. If you use a stereo plug on the bell piezo as well, you can hook up the choke from the edge to the sleeve / ring of the bell piezo stereo plug and then the edge, bell and bow will all choke. Personally I think it's more realistic to not choke the bell because this is how it works on an acoustic drumset.

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                        • #87
                          That's probably the route I'll be going (not choking the bell). So this diagram accurately explain what I need to do (minus the extra KR circuit connected to the bell), right?

                          *edit*
                          let me add the diagram!



                          Actually, this is what I want more, right?
                          Last edited by MrSamurai; 04-24-08, 05:12 PM.

                          -- Setup -- DIY -- Rock Band Converter --

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                          • #88
                            I currently have a single zone ride connected to an Alesis D4. It's very unsatisfying and I'd like to modify the ride to support two zones using the Alesis D4. The D4 is my problem as it only provides simple single-zone inputs with absolutely no grouping functionality. I'm fine with utilizing two separate inputs and assigning a bell sound to one of them and bow to the other. However, what I'm completely confused about is if I can harness the power of the Raper circuit to effectively disable one of the piezos/zones automatically, thus completely negating crosstalk handling requirements in the D4. It seems like it will, however I don't see any language specifically referencing connecting it to an ancient and dumb brain like I have. I'm referring to the DRUM brain, though in this case my human brain might fall under that statement....

                            I seriously doubt I can config the D4 to successfully compute 2 simple true single-zone piezos physically mounted to the same cymbal successfully. It'll be mistriggering both sounds simultaneously for sure. Now that I sais that, I'm going to go sticky-tape another piezo to the bell and see if the ancient D4 can XTALK it's way into a 2-zone ride and answer that question.

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                            • #89
                              Actually two separate single zone piezos on one cymbal actually works quite well. You just have to play with the re-trigger, threshold and crosstalk settings (assuming you have those on the D4, I had them on the td-3)

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                              • #90
                                Originally posted by sae View Post
                                Actually two separate single zone piezos on one cymbal actually works quite well. You just have to play with the re-trigger, threshold and crosstalk settings (assuming you have those on the D4, I had them on the td-3)
                                I don't disagree. But to do so I literally have to max the XTALK (crosstalk) settings and sometimes bump NOISE settings as well. And I still occassionally get some mistriggers. It'd be better if I could implement a circuit that'd cut the unused piezo off completely. It's just not clear to me if this particular thing is correct for my situation.

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