# Impossible Circuit - Any Ideas?

Discussion in 'Electronic Design' started by aaronej, Nov 22, 2006.

1. ### aaronejGuest

I saw this the other day and I was mystified. The circuit has a green
and red light bulb, and a green and red switch. Initially, the red
switch turns the red bulb on and the green switch turns the green
switch on. When both switches are on, both bulbs are on

Here's the catch:
When you switch the Red and the Green Light bulb, the red switch still
controls the red light bulb and the green switch still controls the
green light bulb.

Can anyone explain or diagram this?

2. ### Phil AllisonGuest

** Groper alert !!

** The supply is AC and the bulbs have diodes fitted inside them, wired in
series with the filament.

The switches also have diodes in series with them.

So, the lamp sockets are simply wired in parallel and it make no difference
which is used.

......... Phil

3. ### JamieGuest

sure, they had diodes on the switchs and bulbs.

4. ### Iwo MerglerGuest

There is also an alternative series circuit:

+-----+-(X)-+------+-(X)-+---+
| | | | | |
| +-|>|-+ +-|<|-+ |
o |
AC ~ |
o |
| +-|>|-+ +-|<|-+ |
| | | | | |
+-----+-*/*-+------+-*/*-+---+

Again the diodes are inside the bulb socket.
You can swap the bulbs with baffling results
and it won't work with one bulb removed. ;-)

It's a fun circuit when built on clear perspex.

Kind regards,

Iwo

5. ### MikeGuest

It's a "magic trick" ... sounds like ... US Patent No 5790013 ?

See http://www.freepatentsonline.com

6. ### Mike MonettGuest

Mike, how on earth did you find that patent?

There's no way I could have searched the patent database and come up with
that number.

You should patent your search method

Regards,

Mike Monett

Antiviral, Antibacterial Silver Solution:
http://silversol.freewebpage.org/index.htm
SPICE Analysis of Crystal Oscillators:
http://silversol.freewebpage.org/spice/xtal/clapp.htm
Noise-Rejecting Wideband Sampler:

7. ### DonaldGuest

This is so silly.

A patent !!! for this !!???

No wonder many say that the US Patnet office is in dire need of house
cleaning.