Magic: The Mini-magic Switchboard should I make it a kit?

[wmmullaney]

Thats sorta how I put it, I deleted my post so you would figure it out on your own.

 

[Marks256]

Oh..... That makes sense. Bill, let us know an estimate of cost. This would be fun to confuse people with....

 

[wmmullaney]

I'm just going to build one. That's an awesome trick!!!!

 

[blueroomelectronics]

Sure, you'll need 4 switches with removeable colored caps, 4 colored light bulbs, 4 driving transistors & a PIC16F628A would be a good choice IMO. A 0.1uf, 1n4148 (drops the voltage a weebit) and 4xAA would be perfect. Run the bulbs directly from the batteries and through a 2N2222A with a 470ohm base resistor should make 6v blubs glow brightly enough.
Software should be pretty stright forward.

For extra points use the 38khz internal clock (low power, shorter delay loops) and the wake up on portb (with pullups too) and your Magic box will run for ages on a set of batteries and won't need a power switch.

 

[Hero999]

Normally I'd suggest LEDs for this sort of thing but in this case incandescents are a must as we want it to look as low-tech as possible.

 

[wmmullaney]

I'm going to use leds.

(Eliminating transistors)

 

[Marks256]

Sodium Floodlights would be cool, too...

 

[blueroomelectronics]

I agree with Hero999, LEDs look too high tech, you want this thing to look simple, plus you'll have to have sockets for whatever you use. One version of the trick uses an Edison logo to make it look like its from the 1900s
I'll draw the schematic and post it here, maybe even on the projects page of my site.
Its almost too simple for a custom PCB but I'll see if I can draw it on a vero-board like Nigel uses in his tutorials. After all the only parts on the PCB would be the PIC, a cap or two, the diode, transistors and a few resistors (yea I'll use a mclr pullup so you can reprogram the thing with maybe even better tricks) all the other parts would be offboard. Batteries, switches & lamps.
Based on how popular this thread appears to be I guess we all still enjoy a magic trick.
Ps wooden box is also a good idea, the more last century it looks the better. You can buy small simple boxes at may dollar stores... (Use the sliding lid on the bottom for the batteries eh)

 

[Marks256]

I think i am going to give this a go with my BASIC Stamp (since i can't do assembly yet...) I like this.

I just watched it again, and it makes sense now.

 

[3v0]

I would be happy to do a SS PCB and post the Eagle files and a foil pattern.

 

[blueroomelectronics]

I'm not at the office so I'll have to just describe the design as I see it.

16F628A
PORTB 4-7 switches (common ground)
PORTA 0-3 470ohm to 2N2222A base
all base belong to us, err gnd
4xAA to + to lamps and the 1N4148 (drops the batteries 6V VDD to 5.3V for the PIC
Emitters to lamps
Add a couple of decoupling caps and you're done.

 

[bananasiong]

I was thinking of using LEDs as well, but wait, what to hold them like the bulb? Furthermore LED is polarized, maybe this can be use as another trick?

 

[Marks256]

make a polarized jumper. like a 4 pin stand off with one pin missing. that way it can be plugged in only one way.

 

[blueroomelectronics]

Or you could drive the LED with two I/O pins and alternate the I/O so it would light either way.

 

[Hero999]

If you must use LEDs you can get them in standard bulb fittings but they don't really look like bulbs.

The only trouble is that if you use LEDs it'll make people more suspisous that they're bugged.

I like the idea of building the mains version, that way you could demonstrate that it will work with any standard bulb, even energy savers.

Emitters to lamps

I'd put the collectors to the lamps and the emitters to 0V as less power will be dissipated in the transistors and the bulbs will be brighter (lower volt drop).

 

[bananasiong]

Yes, higher Vce drop if the load is at the emitter.

 

[3v0]

I did not hear from anyone regarding a PCB. I will hold off on bulding mine in favor of getting other projects done.

 

[wmmullaney]

I'd like to see it 3v0.

 

[3v0]

I'd like to see it 3v0.

Do you want to use LEDs or 5V lamps ?

For LEDs I have a nice little 16F88 board layout that will work as is.

It would only take a few minutes for me to add transistors to drive lamps.

EDIT:
I am cleaning/rearranging my office/workshop/lab and any excuse is welcome!

 

[blueroomelectronics]

I've got to check my junkbox for 6V bulbs. Finally something old that Radio Shack probably stocks. Bulbs & Sockets.