< 0.5 volt relay?

[baskentball]

Obviously my motive was misconstrued, I appreciate those willing to help.

Thank You

 

[Externet]

Not simple for a rookie as you say to 'build' such relay, but seems that there is several other ways to do it without getting into relays.

A relay typically uses not less than half a watt to pull the machanical contacts as there is a spring to fight against, and a gap the magnetism has to pull across.

A low voltage relay coil means less turns, on thicker wire, and will conduct more current to do the action of moving mechanical contacts. To about the same, over half a watt.

0.5 Watts ÷ 0.4 Volts = 1.25 Amperes ---> 0.32 Ohms coil

Such current may be not available with certain batteries in your circuit.

So if you explain better your intended application, other solutions could be suggested.
Miguel

Note: You mention "source current" of 0.4V. That is improper, current unit is Amperes.

 

[baskentball]

Read above if interested.

 

[Externet]

The signal present on the wires that feed a speaker is alternating current -when there is audio presence- and not direct current as a led prefers to work with. Pushing the transmitter button alone does not produce audio at the receiver speaker wires.

The flash you see is from some inherent glitch.

If the two way radios are for voice communication, there is a remote chance you can succeed, by connecting -better two- counterparalleled leds instead of the speaker and set the volume full blast at receiver "B" while screaming your guts out at the microphone of transmitter "A". That may work only while screaming, not while pushing the transmit button.

Better use radiocontrol transmitter and receiver so the servo can move a contact to turn on the led.

Miguel

 

[mneary]

Something like this could be used to very unpleasant ends.

 

[audioguru]

Another terrorist asking for a way to remotely detonate his bomb.
Instead, let him blow himself (herself?) up like all the others.