2
\$\begingroup\$

I've been messing a bit with EL wire that I purchased from amazon, I dissected the control unit and it appears to consist of a transformer, timing circuits(s) and a push button. When you push the button it toggles through the different modes (solid, blink, blink fast).

I want to try and control the wire in a very basic manner from an arduino. I simply want to toggle through the different states. How would I apply voltage or PWM across the contacts of the pushbutton to simulate a push

enter image description here

\$\endgroup\$
5
\$\begingroup\$

The closest thing to simulating a real push button would be to use a reed relay, such as these. This particular one with a 5v coil voltage is available from Digi-Key for $1.10; there are others available with 3.3v coil voltages.

The advantage of using a reed relay, is you just wire the contacts in parallel with the original push button, and don't have to worry about how it fits in with the rest of circuit.

The following circuit can be used to drive the relay:

enter image description here

The wire on the left (going into the base resistor R2) comes from the AVR output pin. The pull-down resistor R1 keeps the transistor off in case the output pin on the AVR is put into an high-impedance state (e.g. when the microcontroller is reset).

\$\endgroup\$
2
\$\begingroup\$

First: You find out if the push button connects to the power on the input side (has a very low resistance to either + or - of the input supply). It is very likely that it will connect to one of the power rails, which makes it easier.

  1. It does: You can use a bipolar transistor or a MOSFET to close the circuit, as long as your arduino and EL-wire share the same power source. If the button connects to the positive supply, you use a PNP transistor or a P-type MOSFET. If it connects to the negative supply you can use an NPN or N-type. If they don't share the same voltage source, you can use an opto-coupler as described in 2.

  2. It does not: You can probably still use an optocoupler, if in operation the two contacts present more than 1.5V of difference consistently and in a predictable DC orientation (+ always on one contact and - on another), which it most likely will, since that's easiest to design. Then you can try to connect the collector of the output of the opto-coupler to the positive one, the emitter to the negative one and drive the LED with your Arduino.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.