JerryG posted:Alex,
Thanks for your answers to my three questions. Your help is greatly appreciated.
I am going to build a mall scene similar to yours shown on this page. More questions:
How high are your storefront cutouts? They look to be 3-4 inches tall. The size looks perfect and I would like to duplicate the scale.
They are 4" high x 5" to 6" wide. However, the cutouts to tel the light shine through are smaller to match the 'glass' of the store fronts. See pictures below.
What paper did you use to get the lights to show through? I normally use top quality photo paper, but it seems too thick to get light to shine through it.
I used regular paper, which proved to be thin enough. BUT, over all the store fronts I used laminating paper, which is shiny, and provides a nice affect.
I will do a row of LED's outside the cutouts, but it looks like you built a backstop of a sort to mount LED's a few inches behind the cutouts. Is that correct?
Yes, see the picture below. Also, I had to dim the LED's in front (added several diodes in series to drop the voltage) as otherwise the LED's would be too bright and not allow the LED's behind to created the effect of a lighted store.
Finally, what tool(s) did you use to cut the foam arches so smoothly?
Hot wire, primarily, and an X-Acto knife.
Jerry
Hi Jerry,
First, your previous question: "Could you explain function of flyback diodes you add across the relay coils."
A simple explanation: When energized, the relay coil is magnetized, and when its power is shut off, this magnetic field collapses and generates a voltage spike that can be transmitted back to the power source, and this spike can be damaging to some components. The 'flyback' diode, due to the way in which its polarity when it is added to the circuit, does not affect the power applied to the coil; but when the relay is turned off, the voltage spike generated by the collapsed field is of opposite polarity, and the diode acts as a short, sending the spike back through the coil itself (flyback) until the energy is dissipated, which happens almost instantly. Therefore, the diode prevents the potentially harmful spike from causing any damage to other components. Other guys in the forum can probably explain this better than I can, but you should get the general idea.
Here are the pictures mentioned in my interspersed answers in your quote, above. The front LED's that I mentioned are mounted on the inside of the 'concrete' walls and shine on the store fronts.
Alex
