Homemade wireless telegraph demo

[@aravindkramesh]

Great. I am going to make one too.

[@cheeseloaf7788]

I used to have the same radio, the connection for an antenna is at the back,

[@JasonBraatzC]

Great experiment for kids! What amplitude are you tuning into on AM? (Or is it interference at any frequency causing the radio to make a sound)?

[@yhisae608]

This is a spark gap transmitter, which means it makes noise on all frequencies.

[@bobbrock4221]

Looks like a bunch of evil sorcery to me.

[@yadadi4438]

is it neccesary to have the coil part?

[@yhisae608]

For this design, yes the coil is important because it forms an electromagnet, and the rapid on/off of that magnet is what makes the spark generator work. Here's a resource that we referred to; it includes pictures and diagrams that explain some of how the spark mechanism works: www.w1tp.com/perwirls.htm

[@AlexBurtonMusic]

Can we transmit signals over longer distances by increasing the current supplied to the electromagnet or should we use an induction coil instead?

[@yhisae608]

Either one should help to increase transmission range, if I understand things correctly (but I'm no great authority on this topic). Induction coil is harder to build so we skipped that; ours just uses the antenna (long string of alligator wires) for resonance. See this article, en.wikipedia.org/wiki/Spark-gap_transmitter#Theory_of_operation , which mentions the distance limitations of our transmitter: "The earliest spark-gap transmitters before 1897 did not have a resonant circuit; the antenna performed this function, acting as a resonator. However, this meant that the electromagnetic energy produced by the transmitter was dissipated across a wide band, thereby limiting its effective range to a few kilometers at most." (If you build an induction coil, I'd love to see it!)

[@adityasuresh6607]

Great

[@engirckt5410]

you made a dream