Series circuit with Parallel capabilities?

[Atom Smash40]

So, I need help from anyone who is good with electricity. I need to make a simple circuit powered by a 9V battery that can power 4 very small lightbulbs (49s), and if I disconnect one of the lightbulbs, the rest stay lit. Problem is, it's a series circuit that must be made (all 4 bulbs must be connected by wire), and with series circuits, you can't disconnect one and have the others stay lit. Can anyone tell me how to wire it like a chistmas light thing? I know you need a 3rd wire to complete the circuit if the bulb is out, but how do I do that?

[shawn3090]

You could try using a resistor to "short" the bulbs, except that you use one with a greater resistance than the actual bulbs. This way, they only kick in when the bulb dies.

[Doomster]

Resistor is close, but if each of the 4 bulbs will run at 2.25V (1/4 of the 9v), then you could have a 2.7V Zener diode across each, to complete the circuit with a little more votage drop - NB. if the supply voltage exceeded 10.4V, the string of zeners would conduct and overload.

 

Not sure if they are available in 2.4V versions (for less voltage loss on bulb fail, but a supply voltage maximum of only 9.6V).