Useful Links Screen printing isn't just for t-shirts anymore! You can design and print your own electroluminescent displays. See the EL files page for more information.
Briefly explain the basic operating principles of electroluminescence.
Examine the power supply schematic below . The transformer turns ratio is 1:75. The PWM pin is connected to a pulse width modulation pin on the Arduino. The design of this power supply was inspired by the design here. What determines the output voltage of the power supply? What determines the frequency? What should the PWM duty cycle be ?
What is a TRIAC? How is a TRIAC different from a standard transistor? Why do we need TRIACs for this lab?
Examine the cross section of a screen printed EL display. Describe the purpose of each layer.
What are some advantages and disadvantages of screen printing?
For simplicity, you are supplied with a pre-built power supply
based on a circuit known as an inverter
. Although not identical to the circuit above, the two circuits operate under similar principles.
Assembling the EL Drive Shield
- 1k resistors at R1-R8
- MAC97MAC97A8,412 Triacs at T1-T8
- Male headers on bottom
- Female headers on top
- Molex connector for attaching inverter to pcb
- Ada-Fruit Inverter
Make sure the components are oriented correctly. A finished board is shown below:
Observe the jumper wire. You will need this to connect the the digital and high voltage grounds.
Connecting the EL strip
The commercial EL strip has three segments with a common electrode. The common electrode (the blue wire) should be connected to the HV from power supply. The segment electrodes should be connected to EL1, EL2, and EL3. To test the operation of the circuit, load El.pde onto your Arduino and run the sketch. You should see the different segments of the EL strip flash in alternating fashion.
Printing EL displays
Dupont(TM) Luxprint(R) Materials. Link
Ulano Screen Making Products. Link