Powering a Hall effect sensor from the ED10 USB Host Port

[dsteinschneider]

Notes about this thread
This thread is old and relates to first generation eDRUMin device (ED101, ED4R1). Newer versions of eDRUMin devices can easily power Hall effect sensors directly from pedal input ring or tip connection.


My DIY hall effect sensor also has a somewhat narrow green bar but my ED10 original version (are we calling it v1 yet?) plays well with Superior Drummer. I did adjust the curve so the initial open takes more movement. One time during all the updates my green band was much wider. I've meant to look back into that. Since my pedal is DIY I can make whatever changes might widen the band. Rob - do you have any advice for a standard Hall Effect sensor/neodymium magnet setup to maximize the pedal travel sensed by the ED10?

[Rob]

First and foremost, you should check out page 33 of the eDRUMin manual for information about setting up Hall Effect Sensors.

Assuming your designs is drawing power from the TSR jack, you might consider powering the sensor from the USB host port instead. The first generation of the ED10 can't supply enough power for most Hall effect sensors from the ring pin of the TRS pedal jack. Using the 5V from the USB Host port with a suitable voltage divider, you can easily get a nice and stable 3.3V supply and you'll get a much wider calibration range. For others reading this, ED10R2 and ED4R2 and up are all capable of suppling enough power via the ring connection of the TRS jack, so there's no need for external power.

[dsteinschneider]

Thanks for the info on using the USB host port to supply power to the sensor. Can you please give me more info on what I need to do regarding the voltage divider? I think what I'll do to test this is solder up a female TRS that will accept the cable running from the pedal and split the ring off to go to the USB host port. A while back I bought some USB A male connectors that are intended to be used for power. Would you by any chance have a wiring diagram for what I should do. Should the common and the ring go to the USB male connector?

Thanks, looking forward to this project!

[Rob]

I'll test here first. What sensor are you using?

[Rob]

This is only for ED10R1, not the current ED10R2.

This circuit will give you 3.3V even after accounting for the 4.7V from the Host Port and voltage drop due to the resistance of the Hall Sensor. You can probably even use up for 100 ohm resistor in place of the 75 ohm, but this wasn't tested.

powerHallFromUSB.png (102.37 KiB) Viewed 5822 times

This gives me an effective calibration range as shown below:

range.png (2.11 KiB) Viewed 5819 times

[dsteinschneider]

Hi Rob,

I'm using the Bestol A1302 Ratiometric Linear Hall Effect Sensor Chip. I bought 10 of them on Amazon a while back.

Doug

[dsteinschneider]

I'm shopping resistors - does anyone have a preferred assortment set? I'm not in a hurry so Chinese suppliers would be OK.

[Rob]

The datasheet for your sensor says it needs 4.5 - 6V, so you can do omit the 200 ohm resistor. In fact you can omit both, but the 75ohm resistor will protect against drawing too much current if there's a short circuit.

One thing to point out is that ED10 will not be happy if the voltage on the tip pin goes over 3.3 V. It likely wouldn't cause any damage if it did, but something to keep in mind.

[Rob]

On a side note, I've tweaked my pedal sensing algorithms and I can now detect when a pedal/controller with an externally powered sensor is pulled into the pedal input. Should help to make things easier for the ATV hihat.

[dsteinschneider]

Can I substitute a 100K for the 75k in my situation? The assortments I'm looking at don't seem to have 75K