Circuit to represent operating scale TV?

Lee, I have a "flicker" circuit that is based on a Picaxe microprocessor; one chip, a few components and a bit of programming provides a realistic flicker for a fire.  Could work for a TV.  However, I'm pretty sure there are cheaper commercial circuits out there.

Ron L

You could monitor a real TV for intensity changes for a few minutes, and then try to duplicate it.

 

If you wanted to do this, you'd also probably want multiple colors to make the screen change colors like the real deal as well.  Something like several of these RGB LED's behind the screen and both being randomly cycled would work.

Or if you want to go with several small TVs, you could go with a fiber optic to each TV and then use a color wheel located elsewhere to vary the color/intensity.

Lee

just curious  

Shouldn't it be a black and white TV? 

 

Clem 

Very good point Clem!  It probably should be B/W, easier to do.

If you don't want to go the programmed-chip approach using an Arduino, Picaxe, or the like then I'd look into so-called pseudo-random-number-generators typically implemented using digital shift registers and gates.  The theory is described here:

 

http://en.wikipedia.org/wiki/L...dback_shift_register

 

Note that while there are many algorithms for generating random numbers, I'd say the most common type used in Arduino, PicAxe or whatever software is in fact the method described in the above article.

 

There are many links to home-built circuits, but here's one I found that kind of shows the complexity of the hookup for what would work for you.  It's written by a ham radio guy which is usually a good sign as these guys are of the practical DIY ilk. It's maybe $2-$3, a few digital chips, assorted resistors, capacitors, but a bunch of soldering.

 

https://jaunty-electronics.com...mber-generator-prng/

 

To generate the multi-level brightness you want, you'd simple sum together two or more outputs from the shift register.  In other words, rather than a 1-bit generator with on or off, you could use a 2-bit generator with 4 different levels, or a 3-bit generator with 8 different levels, etc..

 

There are many implementations of the welder flicker circuit but you might be able to find one where you can slow down the clock (oscillator) since you want something that changes every few seconds rather than many times per second.  That would usually involve changing a resistor or capacitor value.  I also don't think most hobby welder simulators offer multiple levels of brightness but that's another story.

 

The digital shift register noise generator (aka Linear-Feedback-Shift-Register) is actually simpler than it sounds so if this is a direction you'd like to pursue, I will provide additional thoughts.  You're the first person I've heard ask for something like this to enhance a train layout.  Thumbs up for your imagination and let the games begin...

Ngineering may have what you are looking for on their website.

 

Installed one in the living room of a house a month ago and the guys have been sitting around enjoying pizza and beer since then.

 

Now trying to get the audio working with I Love Lucy soundtrack. Assume you will do sound also so please let us know how you do that.

Thanks.  I'm not sure what I will do.  I have a couple of ideas though, including one weird one I might do just because.  I'll post what I do, whether it works or not, but it will be a month of more before i get to it. 

Looked up this AM.

 

Ngineering TV flicker simulator, part N8067, $13.95.

Sounds like just what Lee needs, too bad they don't have a video yet.

 

Maybe Lee can find one of these.

 

 

Pete

 

 

Best solution yet, but it would be a 65" screen TV in O-scale!   Probably not period correct, the 1950's didn't have such animals.

 

Thanks. I ordered one.  We'll see how it works out.  

Wow.  It is tiny!  the board is about 3/8 square.  I could fit it inside a 1:48 scale 1950s TV cabinet.  

 

It has a very miniscule power limit, about 1/3 watt max, which may not be bright enough: I actually want enough light that the flicker lights up the room like you see when out walking in the evening - you can tell someone is watching a TV through even closed curtains, but we'll see.  

 

 

1/3 of a watt will light an LED pretty bright, you may be surprised.

 

I agree.  1/3 Watt driving an LED is equivalent to a 2 or 3 Watt incandescent bulb which should adequately light up the building.  Plus,  the difficult part of creating a signal that simulates TV flicker is done and has been programmed into a chip.  Further buffering/amplifying that signal to drive, say, 1 Watt or more is maybe $1 in additional parts plus some sweat equity (soldering).

Well, I will find out soon enough. 

 No circuits, but "mad scientist" ideas? Sure. What about a little dollar store ear bud, or keychain radio as a driver? The "speaker" disconnected. Pulses for the speaker driving the led instead. Id think the voice pulses would vary enough to simulate t.v. nicely. Maybe if it has separate equalizer channels, run off each of those separately, each driving a leg of a multi-color led. If that one isn't enough by itself, another one,  along with that, but capped, might add well to the effect, by having a different hue & less total blackout times.  

 A breadboard type radio wave "detector" could do it too. A poor receiver of sorts, like a Geiger counter. Careful, built slightly incorrectly, it just might become a low power FM noise generator capable of blocking General Hospital everyday at 3pm from 20ft, but letting Bugs Bunny's station tune in fine Sounds like something a sixth grader would do right?(sorry, Sis). 3/4"x1.5"x2.5" handmade alum box & a nine volt. I haven't made a radio circuit in 30yrs.

 

I think most noise generators, flashers, would be too constant.

 

 Excuse me Sir, Have you looked at our latest? A console model!... Could a block of clear, within the console, and well lit from underneath the floor, by a larger led be the answer? Foil reflector surfaces on the clear block?(a modified chunk of turnout lamp prism?) 

Lee we installed it to do what you want... see from outside, etc and it does fine. We didn't use curtains. Please let us know what you find out.

 

No trains for a few days. Left Va Beach Friday AM to take a boat to Isla Mujeres , Mexico. East of St Augustine now.

 

Hope it works okay For you.