Smallbear Actuator w/ Magnet and Hall Effect Sensor

[electrosonic]

The actuator is from Smallbear - http://smallbear-electronics.mybigcommerce.com/switch-actuator-for-b-o-b/  ($1.95)

I got a 1/4" cylindrical magnet and scavenged the spring from a battery holder

I have tried it with a OH3144 Hall Effect Sensor (available for $0.10 each on eBay).

http://www.ebay.com/itm/10PCS-A3144E-A3144-OH3144E-Hall-Effect-Sensor-/171987042609?hash=item280b3a0131

I will design a pcb that sits just below the actuator to control a relay. The sensor has a schmitt trigger so debouncing should not be necessary. The variables to work out are the magnet strength and distance from the sensor. I have tried it on the bread board and it works as it should. I plan to control the relay with a uC or a 4013 flip flop.

The set up is reasonably cheap and should be much more robust than the standard 3PDT bypass.

The hardest thing to source is the spring. I can find them online for about $1.50 each with a minimum $50 order.

Anyone gone this route before?

Andrew.

[PRR]

Any hardware store has a drawer of assorted springs.

IAC, hacking battery holders may be cheaper than sourcing springs.

Of course your plan only gives a logic signal, doesn't switch audio directly.

[electrosonic]

Any hardware store has a drawer of assorted springs.

You would think so. Was at a sizeable Home Depot today and was told they don't sell compression springs. Maybe it's a Canadian thing.

Andrew.

[PRR]

Unless you have a good relation with the short woman in the plumbing aisle (she knows all), don't trust the clerks.

Get in the website, find your store, look up these part numbers:

Zinc-Plated Compression Spring (6-Pack) Model # 16087
Spring Assortment Kit (84-Pack) Model # 13554

These may not be your springs BUT the "Aisle 16, Bay 008" (different in each store) tells you where to look. Aisles are marked well. Took a while to discover that each "bay" (an 8-foot rack) has a sticker number. So now you see 8' wide by 6' high of small drawers with pictures. Happy hunting.

[LightSoundGeometry]

i hope youre successful and the price of stomps drops significantly ..I grew up with a marhsall and a cheap bently strat with single coils so I am used to pops, hums, buzzes and quirky strange noises..makes me sort of hendrixy 

[amptramp]

Retractable ballpoint pens have a compression spring inside.  Even some fixed pens have them.  They will be small diameter and rather weak, but they are everywhere.

[Transmogrifox]

What about using opposing magnetism to replace the function of the spring? 

I haven't got my hands on one of those switch actuators to see how the spring mechanism fits, but my imagination says a pair of magnets and some epoxy might make a suitable and cheap replacement. 

My wife got a pack of what seem to be really powerful refrigerator magnets that give as much opposing resistance as I would expect from a suitable compression spring at 1/2" distance and I don't remember that a pack of 12 was more than a few bucks.

[disorder]

What about using opposing magnetism to replace the function of the spring?

I played a lot of paintball in high school and one of the popular mods back then was replacing the spring in triggers with two small rare earth magnets adhered to gun and trigger. Worked great and had a really nice snappy tactile feel, which I think would happen here as well. I'm not sure how this would work though since you want to bring the magnet near the hall effect IC and still need a magnet near by to provide "return polarity".

[Transmogrifox]

I'm not sure how this would work though since you want to bring the magnet near the hall effect IC and still need a magnet near by to provide "return polarity".

I envisioned a total of 3 magnets:  2 emulate the spring and the 3rd is pushed toward the hall effect sensor.

I'm not sure how it would work either.  I would need to have my hands on the switch actuator to really understand the places and the spaces. 

Theoretically speaking just pushing two opposing magnets together will change the magnetic fields surrounding the pair and one would think it could be cleverly done with 2 magnets.  All you need is for the hall effect sensor to detect a significant change in magnetism and then you can convert the resulting bump into a toggle pulse. 

[electrosonic]

What about using opposing magnetism to replace the function of the spring? 

I did try that unsuccessfully. While using two opposing magnets makes a nice springy switch - it doesn't actually toggle the sensor, because the magnet closest to the sensor is stationary - the upper magnet is the one that moves, at least in the only opposing magnet configuration I could think of.

The a conical compression spring works well because it compresses down to less than 1mm in height and won't be deformed by repeated use (I think regular compression springs might not hold up in this application).

I will make a pcb this week and send it off to OSH Park.

Andrew.

[thermionix]

Don't have measurements, but very similar springs are often used with Strat pickups.

https://www.allparts.com/GS-3036-B05-Bulk-Pack-of-50-Pickup-Mounting-Springs_p_1818.html

Might be able to find cheaper ones on eBay or Aliexpress or other Chinese outlet.

[Rixen]

I'm most of the way into a hall effect actuation in my enclosures triggering microcontroller and latching relays.. you can expect a very long life..

Some hall effect switches consume quite a bit of current, but others use a sleep mode most of the time and wake up about 10 times a second to sense if anything has happened. And still quite cheap @ 20c.

I also had problems sourcing springs- there doesn't seem to be standard sizes that you can reliably come back to and buy again.

So I got them made, ~USD $0.50 ea in 250 quantity at a local factory...

[electrosonic]

Don't have measurements, but very similar springs are often used with Strat pickups.

Those look about right - thanks for that - I ordered some on eBay.

The OH3144 draws something like 4mA - I don't use batteries so not a big deal.

I already use a latching relay set up, so I will use a CD4013 or a micro controller depending on the application.

I would rather not have a uC in every build - seems like too much potential for heterodyning with charge pumps or if the pedal already has a uC for a LFO.

I will upload a pcb to OSH Park today (it uses a CD4013 flip flop)

Andrew

[Rixen]

I kept getting asked if I sell an enclosure with two switches, but I can't do this without new tooling at tens of thousands of dollars. So I thought I would test the market for a sequential switching arrangement- hence the micro.. sequential won't be to everyone's liking, but the investment to try out the idea is low.. and the parts cost is similar to a good quality latching switch.

I think you will be pleased with your results using hall effect actuation.