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3.5mm jack as normally open button

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ryrhoades

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shortbus=

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That port is stereo, meaning it has three different "live" portions to it. It looks like the cable/switch your using is only a two conductor. Are you using the correct sections of the port? Check to see, the sections of the port should match the positions on the switch plug.
 

gophert

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I am a mechanical engineering student working on some electronic projects. Physically, we need a 3.5mm port, where this button (https://www.ablenetinc.com/technology/switches/specs-switch ), can be plugged in, and switch the circuit on and off. Are all 3.5 mm ports capable of this? The port currently being used that is not working is this one: https://www.amazon.com/gp/product/B01DBNI0PE/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1 .

Thanks in advance for all the help.

Search Amazon for: 3.5mm mono jack

This will give you many choices. One complication that is easy but you should be aware of, these mono jacks have 3 pins on the bottom (or back). Two of these pins are connected (via spring pressure) when there is nothing plugged into the jack. They disconnect when the plug is inserted. Make sure you solder to the correct two pins - check continuity to be sure which two you need b
 

ryrhoades

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it makes sense to me after researching what yall have said that the proper 3.5mm jack needed for this is a mono jack. The project is very similar to the switch adaptive toys you see altered for children with disabilities. So when the switch is pressed current is flowing, when it is not pressed, current is not flowing. A switch with 2 conductors, such as the one in the link above, will not operate correctly with the stereo jack - no matter the wiring configuration?
 

gophert

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You can try plugging in the ablenet switch and check if two pins on the stereo jack switch. It is likely that you will find the correct pair because, back in the 1970s, some people plugged mono-headphones into a stereo Walkman and everything worked. So, give it a try if you already have the stereo jack.

One thing you must be aware of, there may be some intermittent issues on the exact position of the plug into the jack - it may not fit securely and click into place well. I assume you are not using this to control a wheelchair or something critical.

Also, do not allow more that rated current through the switch. There was someone on one of the forums putting about 10 amps from a Barbie Power Wheels through one of those switches and wondered why it burned up.
 

ryrhoades

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It is not controlling anything critical, and wont see more than 2 amps. We have mono jacks now and will try this then. Thanks!
 

gophert

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It is not controlling anything critical, and wont see more than 2 amps. We have mono jacks now and will try this then. Thanks!
Check the datasheet. I think you'll find most 1/8" jacks are limited to 200mA to 300mA and sum up to 500mA but, as long as there is no risk of burning down your house, give it a try.
 

ryrhoades

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Thanks for all of the help. I have been presented with another issue for this same project. We have a button wired parallel with this 3.5mm jack so that either the button, or the accessibility switch can be used. We have it working using a bread board, but it will not work in our PCB. If the jack is plugged halfway, it acts normally closed, and when its plugged in all the way, the wires of the accessibility switch heat up, but nothing activates. This is how the pcb is wired currently. Any suggestions?

1556565842065.png
1556565891939.png
 

dr pepper

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3.5mm jack socket switched contacts are most likely designed to switch small speakers, only a few ma.
I see you quoted 2 amps above, this might be enough to ruin your sockets.
See if you can get some data for the sockets, and check the contact current ratings.
 

ryrhoades

New Member
The sockets we are using are rated at .5 Amps and 30 V. We are oscillating up to a about 0.7A . It works fine on a breadboard for extended periods of time at the same amps.
 

shortbus=

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It works fine on a breadboard for extended periods of time at the same amps.
Many times when going from breadboard to PCB, people do one of two things -
1. don't make the circuit the same
2. have a solder bridge somewhere on the PCB, or if home etched a unetched place on the board.
 
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