hello everyone, I'm trying to interface a rhythm generation recovery card with arduino. I am attaching the schematic of an instruments on the board. If I put a 5v connector directly to the pin indicated in red I hear the instrument in output, if I connect a blinking digital output pin of arduino I hear the instrument but much lower in volume. I think there is an absorption problem. i tried to put a an irf520 board before, but i hear only a short click given by the transistor switch and no other sounds. can anyone advise me what else to try?
Nice schematic, thanks. However that pin looks like an analog input, not a digital one. I will take a SWAG and say it looks like a "line input". What is the make and model of the unit. Please define "absorption problem".
Thanks for the reply. the schematic concerns the drum module of an Altair eko organ. I checked with the oscilloscope the pulses in input, they are square waves with a t on of about 20 ms and an amplitude of 4 volts. otherwise it is a typical electronic drum machine in which the impulses are first reduced into positive spikes and then filtered by an analog filter (twin t filters). different types of filters draw different types of timbre. Some instruments work perfectly by connecting them directly to the arduino digital output, while others are very low in volume and I noticed that the arduino's LEDs are lowered in intensity. For this I thought that the digital output of arduino (which is maximum 20ma if I'm not mistaken) maybe it is too low in amperes. other thing that I do not explain is why putting a transistor before the drum input it does not work.
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I do not know either why the transistor does not work, it was not on the schematic. Remember you have the hardware, we most likely have never seen it or how you have connected things.
That sounds insane. You are probably damaging the Arduino output pins. Please post a schematic of your Arduino circuit. However, that seems completely unrelated to your question. The input in the schematic is capacitively coupled so DC signals won't do anything to it.
First I thought, it is modulating the impedance of the twin T by varying the bias on the diode. That will shift the twin T center frequency. But as the input is not DC, it will only permit AC modulation.
But now I think, a pulse (e.g. the 20ms one you mentioned) just injects a pulse signal into the filter, which causes it to oscillate, and of course diminish exponentially, at its center frequency.
So if you replicate the input pulse correctly from an Arduino output, it should work. But it's likely that you just messed up your design and it needs some work. Please post a diagram of that connection/circuit.
It's probably something simple like a missing ground.
this is the complete schematic of organ's percussive module I have done three tests: 1) I connected the gnd of a 5v power supply to the organ's gnd and touching the input pins with the positive wire of the power supply for a short moment. all the instruments sound quite good, some however only at the first touch, the following touches no longer sound 2) I then introduced an arduino by connecting a gnd pin to a gnd of the organ and a digital output from time to time to the various inputs of the percussions board voices. in this case only the instruments that have an inductance in the filter (the most acute ones) sound good, the others play very low. 3) I introduced a mosfet bord like this:
https://www.amazon.it/WINGONEER-IRF520-MOSFET-modulo-driver/dp/B06XHH1TQM/ref=sr_1_4?crid=188H07B25E4I8&keywords=irf+520+board&qid=1660938513&CR0+Caps+board 8-4
putting pins sig and gnd respectively to an arduino digital pin and an arduino gnd pin, the gnd and vin connectors to a 5 volt power supply, and the v + and v- connectors to the input pins of the percussion board and to the ground of the organ. in this case the instruments play only when I connect them to the connectors for the first time, even with the transistor off (actually the v + is connected directly to the 5volt) then many no longer play and I only hear the glitch of the transistor switch. Is it possible that the problem is that I have left the percussion board mounted in the organ? is it possible that the components originally used to activate the percussive instruments, even if inactive, affect the behavior of the arduino?
Too many words to decode. Please post schematics-or-circuit-diagrams so we can easily see exactly what you have done. Especially, the wired circuits and not the experimental wire connections. You should never apply a power source to a signal input of any kind. If you must do that, you are wiser to use a current limiting resistor in series. Even then, you can't be sure what the inputs can tolerate.
I solved it all by removing the unit from the organ. now i can drive it via arduino + max msp. thank you all, as soon as possible I will make a video.
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