In the front they put 2 lightbulbs from a dia projector mounted on an 8-shaped aluminum plate

A couple of external items were attached to the device. One of the more funny items was cut from the internals of a Pioneer TS-1011 dual cone speaker

The device used on the DeLorean TimeMachine is most likely a US army classified device hence the words ‘Tone’ & ‘Voice’ on the back of the enclosure.

On top of the flux boxes of the Back To The Future Delorean Time machine you will find a weird device, usually called the Wormhole Emitter (WHE)

The Wormhole emitter (aka Tachyon Field generator ) was most likely a military optical communication device. Such an optical communication device has been first seen in use by the German army during 2nd World War. In the pictures below you see the Lichtsprechgerät (which translates as light speaking device) also known as Li Spr 80. The range of such a device was 2 to 4 km.