Questions about hall effect setup

[dsteinschneider]

I've read as many threads as I can find here and on vdrums. I still have a few questions.

I bought terminal strips, a pack of Bestol A1302 ratiometric hall effect sensors and some TRS cables.

The N50 magnet I ordered from ebay is lost so for the time being I pulled a magnet out of a window sensor from an alarm system.

So far I haven't gotten any pedal signal showing up on the Megadrum. Here are my questions:

1. My TRS cables are red for ring and white for tip. I connected the copper strands wrapped around each for the ground. If I'm looking at the sensor with the labeled side up (say 1 is left, 2 is center and 3 is right - which wires from the TRS cable go to each?

2. I have the magnet attached to the hi-hat pedal. I positioned the sensor so when I press the pedal all the way down the middle of the magnet ends up 1mm from the sensor. Is that the right way to position it?

3. This magnet seems fairly strong, I tried both ends. Even if it's not powerful enough should I at least see a little pedal signal?

4. What does the MD pedal indicator do when it sees signal from the sensor? Does it draw a line across where it says "Pedal"?

5. I have the sensor flat so the thin edge is against the magnet - am I supposed to bend the leads so it's wide part is against the magnet?

Thanks,

[ignotus]

Are you sure white is tip? A multimeter would be good to confirm. With the narrower size facing up, from left to right, the hall sensor pins are 5v, gnd and signal output. A weaker magnet should still give some sort of reading, but another source of neodymium magnets are old hard drives, there's lots of info on the internet about how to extract them.

If you have a colour TFT screen on your module you should see numbers change beside 'high level' and 'low level'. If it's the older LCD you should see a bar go up and down at the left of the screen.

One of the sensor's flat sides should face the magnet. It doesn't matter which, just test to see which side of the magnet makes it react. It's better to do the testing before putting it all under the pedal to see how it reacts best. In mine, the magnet starts at a distance of about 1.5 cm and stops at around 2 mm, though you can set the distance to your preference as long as it's within the range the sensor reacts to.

[dsteinschneider]

Hi Ignotus,

Thanks for the quick reply and all the other posts you've shared! I used a multimeter to to suss out the tip ring sleeve wires on my cable. I cut the end off the cable Yamaha provides with their PCY135 to connect to the terminal strip.

I was not facing the big square end of the sensor to the magnet.

Funny you mention hard drives. I have hundreds of them piled up awaiting occasional disassembly sessions, if I come across a PC with a spinning HDD I clone them out to Samsung EVO's.

I'll take a few apart now and perhaps combine the magnets.

[dsteinschneider]

Thanks for tip on magnets. I pulled 10 identical magnets out of Seagate Barracuda 7200.1 drives. They are much more powerful than the other two I was experimenting with. I let them assemble into a 10 layer magnet.

I checked the voltages from my TRS cable plugged into input 1. The sleeve (red) is 4.8 volts when paired up with the common. The tip (white) gives a reading of 3.59 for some reason.

I have 10 of the A1302's . I took a new one out, carefully bent the legs at the little notches a few mm from the chip (holding with a needle nose pliers) so the chip is at a 90 degree angle to the plane of the three legs. I applied the 5 volt lead to the left most, common to the middle and the other (white) to the third leg.

No matter which way I present the magnet within 1mm of the sensor I get no reading. I'm wondering if the pack of sensors is bad. I'm on the third one now with no sensing of the magnet.

Should the right most leg send more voltage through when the magnet is near the chip?

[dsteinschneider]

OK, ID10T problem was occurring here. Always RTFM before you spend hours troubleshooting. Always know what all the switches on your device perform. I flipped the switch all the way to the right and now am getting signals.

Not all bad here, I had other things wrong and now have excellent magnets for free!

[ignotus]

Ok so I take it you got it sorted then. Yeah, I've had lots of those doh! moments.

[dsteinschneider]

I'm consistently getting 445 to 720. I guess the important thing is that it's consistent but I'm wondering if that range is typical?

The magnet part turned out to be very easy. The hard drive magnets are very powerful and pulled themselves onto the chain of this low end pearl hi-hat stand. They don't move at all when pedal is pressed up and down vigorously. I'll probably figure out something later that doesn't touch the chain.

I bolted the terminal strip to a 3/16" thick plate with cut outs for the stirrup I then cinched it on with a zip tie. I'll revisit this also.

[dsteinschneider]

Ok so I take it you got it sorted then. Yeah, I've had lots of those doh! moments.

You don't reach level "Serial Tinkerer" without lots of doh! moments.

[ignotus]

There isn't really a typical range - as long as the difference between high and low level is more than 127 it's going to work fine. If the readings are consistent then you're good to go.

You don't reach level "Serial Tinkerer" without lots of doh! moments.

It's all part of the process

[dsteinschneider]

The hi-hat set to CC04 is working really well in Jamstix. I bought it for AI drumming but really like the sample library the developer, Ralph Zeuner, built. I think he recorded his own kits.

I've been fine tuning the threshold and high levels for the other cymbals so they are triggering better.

The Hall Effect Sensor hi-hat controller is amazingly simple and easy to build and works really well. Thanks to all, especially Ignotus, for posting how they built theirs. I will post my own take here shortly.