K9's switches

[fivefingeredstyre]

How do!

So over the last couple of years (on and off  ) I've been building a K9 replica. The intention is for him to be a fully functioning RC prop. and at the moment he looks like this:





All the lighting is now installed but i'm looking to get the switches and lamps on his back to randomly flash, like the original.

The buttons are working, latching panel switches with internal 24v panel lamps, which get pretty warm if they are left on for any real length of time. I really do need to get the things to flash momentarily before they melt his back

Has anyone got ideas on the best (and simplest!) way to achieve this? All help gratefully accepted!

[warmcanofcoke]

I'm sure there will be someone who in a short period of time will produce a circuit diagram that will explain how to achieve this effect.

But a simple answer might be to buy some Christmas tree lights - and shop around I'm sure you can find a set that you can adjust the speed of the flashing lights, and just remove the leds and solder/wire up the connections to your existing K9 switches.

I'm not sure if there are factors that I haven't taken in to account it looks like you are using switches like these


you may or may not have to find an appropriate gauge wire Christmas tree lights. I assume you have already wired up a ground wire to the third pin.

[fivefingeredstyre]

They are exactly the switches! The lamp pins are actually the two outer pins, and the three inner ones are for switching (a Common on the end, with a normally open and normally closed contact pins for switching. Only four of the switches are actually going to be operational (for lighting, drive and power) the rest are wired so that the lamps are in use but nothing else.

The christmas tree lighting controller is not a bad idea, but from experience they tend to work on "channels" where they simply flip between two or three preset circuits and simply flash between them at defined speeds (Does that even make sense???)

I would prefer something more random, that will flip between all twelve of the lamps.

The internal wiring currently looks like this (ignore the untidy, temporary wiring... You wouldn't believe i'm an electrician... )



So all the lights are fed independently (they are crudely looped out at the moment to enable them to stay on...) so that they can be individually switched...

Thanks for your help!

[warmcanofcoke]

well I have been looking on you tube for a tutorial oh how to make lights flash.

I've come across two that don't solve your problem but start to point me in the right direction to try to find an answer.

http://www.youtube.com/watch?v=cW0Ry2xhzxw
(this one involves buying a circuit board)

http://www.youtube.com/watch?v=wwdmvALt-KI
this one makes lights flicker ....

I haven't quite found an answer but I hope this is somehow helpful.

it may leed you to the answer.

[warmcanofcoke]

I remember watching a video that was trying to explain how a microchip worked (probably in the 1980s) and they wired up LEDs to each of the prongs of a microchip and showed the lights switch on and off in a manner that gave the impression of random switching .... I remember the presenter saying they had slowed the microchip down so that the demonstration would be more impressive.


Edit:

found it!
Secret Life Of Machines - The Word Processor

http://www.youtube.com/watch?v=nN9wNvEnn-Q

Items of interest 4:02-6:07 and then 16:30-17:38

[13drwho]

I wrote this long explanation of how to do this, but the session timed out and I lost it all. Private message me and I'll send you my thoughts. I think you're going to have to custom design something becasue the lamps run on 24 volts. 

[fivefingeredstyre]

PM on the way...

Thanks guys

[13drwho]

Salutations,
I was thinking that you need a 4017 decade counter. You would use a 555 timer to create a clock frequency then the 4017 would sequentially step through the 10 outputs. Each output would need to go to a MOSFET to switch the +24 Volts to the switch lamp. The main circuitry on the board would need to run on 5 to 10 volts.

Christmas lights aren't as simple as they sound. They don't run on 24 volts so you would have to have the Christmas light output go to a MOSFET or relay to switch the 24 volts.

Either way you will need to custom make a PC Board. It can be done for a reasonable price at someplace like PCBEXPRESS. They have free software to layout the board and you can order the board on line from them. I designed a similar board for my TARDIS console and it worked really well.

Here is the circiut I would use...



The Jason

[galacticprobe]

Adding a little to The Jason's post - which is a perfect circuit for this project - you can connect the MOSFET outputs to different bulbs in the switches to get that semi-random flashing effect. Of course with only 10 outputs from the 4017 and 12 switches, you'd have to connect one output so it would power two bulbs (so two would flash at the same time), and you'd have to do that twice for all 12 bulbs to flash by using only 10 outputs. (It would be your choice as to which two bulbs flashed at the same time, then have an interval with only one bulb flashing here and there, and then the second two-bulb flash, and another interval with one flashing here and there before the cycle started again.)

Does that make sense? (I know it does to me because I'm an electronics tech, but it might not make sense to everyone.)

Dino.

[13drwho]

If you look at the Schematic I did show two lights on output Q4 and Q9, but you're right it doesn't matter which output is shared. If you connect them out of order to the switches the pattern will appear random to the casual observer. Unless someone watches for a while and really pays attention, they won't notice the pattern.

[fivefingeredstyre]

Guys

Thanks very much for all your help. I will get to work and post a video when i've finished...