I can't tell what equipment you have. Microphones are low signal devices. You'll need a microphone pre-amp to get any voltage from it. Then you'll need a power amplifier to be able to drive your lamp. Driving it directly from the microphone will not work.

Your project is not a new idea but I admire your desire for experimentation. Some people will either discourage you or point you somewhere that can give you a better working project. I'm not going to do that. Just continue what you're doing and have fun. Just suffice it to say that, yes, there are better ways of doing what you want to do but better for you to find out yourself.

Good luck.

Hi john,as i understand ur problem is that you want to modulate the light with sound waves and vice versa,it is no a difficult task,u can do it with LED circuits and it results are good,I also made that kind of project some times ago but i modulate the IR beam instead of light and this kind of modulation is known as intensity modulation.if u have face any problem then contact me at rishi_rajpoot@yahoo.co.in

Your project is, "converting sound into light and back into sound".

But you did, converting sound into electricity and tried electricity to light...?

I you get sound from the speaker, you have some voltage present.

Check your meter's range and scale.

Do you need AC or DC scale?

Some multimeters have a large damping factor, short pulses need to be quite high to make it react.

helloo john

the first step in your exprement is to test a sound amplifier from usual mic , then u can change the speaker with the lamp so it is light will be unstable according to the input sound from the mic

so u can receive the light signal by photo risistance or by photo transistor , whic will be amlified and u can hear the sound from the speaker so u can u use here an audio amplifier but with photo trnsistor or photo risistans as a pre amplifier u can get the electronic circuit from many sighties on the net

any way i do not prefer this way in work coz the normal light is not good in working in this systems cos of the day light and the home light will negative affectivly on your work so try to use infra red diodes IR instead

hooking it up to a tiny portable amp (runs on a 9 volt battery) and still not getting a voltage reading on my meter when held across the speaker wires .

You have virtually no chance of doing any decent electronics without an oscilloscope.

A meter is is a VERY poor substitute and is only really suitable for basic electric work rather than electronics.

(I'm sure someone will argue with me but I'll arm wrestle anyone...)

Mr. Golberg ???? ......