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ELwIre And A Pi...
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

ELwIre And A Pi...

by goobertek on Fri Jan 21, 2022 9:58 am

I know I can't power ELwire from a Pi. However is their a simple way, using GPIO's to turn it off and on or dim it with a Pi?

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Re: ELwIre And A Pi...

by adafruit_support_bill on Fri Jan 21, 2022 10:26 am

Switching the high-voltage AC from an inverter is a bit tricky. Sparkfun makes the EL-Escudo shield for the Arduino. But it should be possible to control it from a Pi.
https://www.sparkfun.com/products/10878

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Re: ELwIre And A Pi...

by rpiloverbd on Fri Jan 21, 2022 10:26 am

You know, EL wire needs AC power. You can control EL wire with a raspberry pi by using a relay in between.

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Re: ELwIre And A Pi...

by goobertek on Fri Jan 21, 2022 11:04 am

Thanks for the quick reply. I appreciate it. Havnt worked with Relays much. Know of a document out there that speaks to it? A tutorial?

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Re: ELwIre And A Pi...

by adafruit_support_bill on Fri Jan 21, 2022 12:06 pm

There are several tutorials online about controlling relays with a Pi: https://tutorials-raspberrypi.com/raspb ... -via-gpio/

However, it is not as simple as just breaking the connection between the inverter and the EL. Running an inverter without a load will kill the inverter.

If you can provide a bit more detail about what you would like to do with it, we might be able to offer some more specific advice.

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Re: ELwIre And A Pi...

by goobertek on Fri Jan 21, 2022 12:14 pm

I don’t have a specific use case yet. Working on a robot. Currently it has a SenseHat for some LES lighting and an Adafruit Motor control hat driving the wheels.

It works great. I was just thinking of adding some ELwire to the design that I could turn off or on with my remote controller (Using Python).

Just bells and whistles. Flashing or dimming the El would be a plus but no required.

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Re: ELwIre And A Pi...

by adafruit_support_bill on Fri Jan 21, 2022 12:35 pm

Simply turning on or off can be done by using a relay or transistor to switch power to the inverter. You cold implement flashing this way also. Although I would avoid high frequency flashing since rapid power cycling is probably not too healthy for the inverter.

Dimming is possible, but more complicated. Inverters are designed to handle a certain range of loads - typically specified as a range of lengths of wire or tape that it can drive.

If you go below the minimum recommended load, the inverter can become unstable and will self-destruct. Exceeding the maximum load won't cause any damage, but the output will become dimmer.

Using something like a multi-channel relay board or the El-Escudo between the inverter and the EL, you can attach various 'dummy loads' to the different channels and combine them in various ways to achieve the desired brightness. The dummy loads can be just hidden lengths of EL wire or tape - or a combination of resistors and capacitors to simulate the load of actual EL.

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Re: ELwIre And A Pi...

by goobertek on Fri Jan 21, 2022 12:44 pm

Which relay would you suggest. I'd prefer to buy from Adafruit. Will the tutorial identified earlier lead me through the process? Havn't read it yet

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Re: ELwIre And A Pi...

by adafruit_support_bill on Fri Jan 21, 2022 12:53 pm

This relay should work for you: https://www.adafruit.com/product/2895
It is designed to plug into a Feather processor. But can be controlled by a Pi.

From the Pi, connect GND and 3.3v. Then connect one of your GPIO pins to the "Signal" input on the board.

The guide will show you how to hook up the load: https://learn.adafruit.com/mini-relay-f ... s/overview

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Re: ELwIre And A Pi...

by goobertek on Fri Jan 21, 2022 2:36 pm

Perfect! Thanks.

Will this relay work as well: Adafruit STEMMA Non-Latching Mini Relay - JST PH 2mm?

With this one I'd avoid needing to solder headers:-)

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Re: ELwIre And A Pi...

by adafruit_support_bill on Fri Jan 21, 2022 4:13 pm

Yes, the Stemma version would also work.

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Please be positive and constructive with your questions and comments.