www.megadrum.info

Back in the history of discussion on the optical hi-hat method (viewtopic.php?f=3&t=422&start=24)

I found this comment by Goodeeny suggesting use of a hall sensor, I don't know if anyone realised what he was talking about since the post was ignored, anyway it seemed like an excellent application and so I have done a few tests.

Details + Video of test
http://deanmurray.net/dokuwiki/drums:me ... at_control

The idea looks like it has a lot of promise, I will need still to consider the mechanical installation but expect it to be quite straight forward to fit between the hats compared to the optical design with the sliding beam interrupter flag etc

Unless you have designs on a better mounting/fixing method I think the optical stuff is hard to beat (sic).
I saw an LVDT on an old organ swell pedal - again very reliable, acurate and easy to make.

ICL used hall effect keys on thier mainframe keyboards. My 70's terminal still works...

Yeah the optical stuff is nice, especially what I have seen by racer52. Mounting arrangement is going to be the challenge, but I do think it has the potential to be simpler with only two parts moving relative to one another and only one being wired.

I am yet to work on it any further at this point though

That LVDT stuff is cool, I've not seen it before.

dm9876 wrote:Yeah the optical stuff is nice, especially what I have seen by racer52. Mounting arrangement is going to be the challenge, but I do think it has the potential to be simpler with only two parts moving relative to one another and only one being wired.

Polymorph looks expensive but it's great for just this kind of problem - Ken recommends it over zCorp printers (£750 call out fees) anytime.

Ok well, I kept it simple and it seems to work great.

-wired directly to the sensor, with heat shrink to isolate and encase.
-Cable tie keeps the sensor in place (bottom cymbal can tilt without moving the sensor).
-axially polarised ring magnet on the top cymbal (allows top to rotate without messing up any alignment etc)

(the second cable with the red and white is for the piezos on the top cymbal)

I have a question. An optical HH pedal with an optical resistor has a noticeable lag and this is why I had to replace the optical resistor with an optical transistor. I wonder if a HH pedal with a hall-effect sensor is free from this lag issue?

Hi Dmitri, No lag is noticeable for me. Sensor is rated for 23Khz. They are often used in sensing toothed wheel on rotating shaft (eg ABS sensor for car brakes) or rotational position in motor control etc so very high speed response.

Note: I've probably gone overboard on the size of the magnet but needing it to fit over the nut dictated the size.

Hey Dean, nice work, I've just completed making one, and it really does work great with the Megadrum + SD2.0. No lag, and perfect response. So cheap and reliable. Ended up costing me only 2 euros!!
I've posted some finished pics on Vdrums to get some more interest.
Cheers mate.
http://vdrums.com/forum/showthread.php? ... post442543

This sort of design reliability can't be bettered. Ace.