Positional sensing testing

[edrumor]

Hi,

I have a little question about PS.
It´s wrong way to have a first wave positive using a Pre-amp or mixer with direct-out and,(with no gain), with phase reverse enabled?

Thanks

[dmitri]

You can try.

[gide_x]

Hello Dmitri !

My drum kit is not finished yet, but in my tests, I've try the positional sensing on the snare pad (custom one with mesh head and Roland cone type) and when I hit very lightly, positional seems to be exact, but when I hit more "normally", positional result is completely random.....

I think my pad is too hot and I must have a voltage divider.... but what is the maximum voltage input to have a good result with the positional sensing ?

Thanks for your answer

Best regards.

JD.

[dmitri]

Hello Dmitri !

My drum kit is not finished yet, but in my tests, I've try the positional sensing on the snare pad (custom one with mesh head and Roland cone type) and when I hit very lightly, positional seems to be exact, but when I hit more "normally", positional result is completely random.....

I think my pad is too hot and I must have a voltage divider.... but what is the maximum voltage input to have a good result with the positional sensing ?

Did you use the precision rectifier as advised in the first post?
The voltage on an ADC input must be below 5V.

[gide_x]

Did you use the precision rectifier as advised in the first post?
The voltage on an ADC input must be below 5V.

Hi Dmitri and thank you for your answer...

Not yet, because my pads are total DIY with mesh head, and I can change the polarity if needed... as I have understand, the precision rectifier is recommended with Roland negative polarity wiring but optional with positive wiring (like Alesis) ?

Actually when I hit lightly my snare pad, PS seems to be "relatively" correct... I would test first with a voltage divider to have less than 5v in peak and if it doesn't work, I would order parts to make the precision rectifier

Thanks and best regards.
JD.

[Maylord.war]

Hi

I'm not very able to draw a pcb, but i've tryed to drawing this schematic for make a pcb.

I have only one doubt regarding the C1 and C2 in parallel on Vcc +5.


The x1-2 and x1-1 are the pin header for snare pad and the x2-1 and 2-2 are for Snare output


This is my first try.

If the schematic is correct i will try to routing the traces to create a layout master direct to print.

Thanks

[Maylord.war]

Dmitri, if i use a voltage divider inside the pad i can be omitted the R1 and R6 ?

Or these resistor should be included independently if the signal is too "hot" or "cooled" ?

Thanks

[dmitri]

Dmitri, if i use a voltage divider inside the pad i can be omitted the R1 and R6 ?

Or these resistor should be included independently if the signal is too "hot" or "cooled" ?

Thanks

These resistors must be included.

[Maylord.war]

Thanks

[ignotus]

Hi,

I built the precision rectifier circuit following the schematic on the first page of this thread and using an MCP604 op-amp. It's stated that if it's 'unity gain stable' (this one is), then C3 and C4 can be omitted - I figured C4 should be left out entirely (not bridged), but should C3 be bridged? On the other hand, I didn't have 15k or 12k resistors, so for the 15k I soldered two 10k resistors in parallel followed by another 10k in series, and for the 12k I used 10k followed by 2k2 in series. My multimeter just died on me recently so I couldn't see the actual values that resulted from this fix, but the resistors are rated at 1% tolerance so they *should* be close enough to the right values, except for the 12k which is nominally 200 ohms over the mark. Would this be a problem?

I'm describing all this because when I tried the board out, the first thing I noticed was that the snare has lost a lot of sensitivity. It has a trimpot to cool it down (it was way too hot), but with the rectifier board I had to completely open it and even so high level is now at around 250, when it used to be at 990. Is this normal?

The good news is that despite the above issue, after messing around for a little while positional sensing seems to work pretty well. My pad is only 10" so I can't expect miracles, but nonetheless I can get fairly good transitions from centre to edge. I have to raise minscan to about 80 but I'll try to deal with that mechanically - I think the foam I use is too soft and lets the head vibrate too much.