Transistor or TRIAC for Omnidirectional Current Flow

[SBlevins]

Hi guys, I have searched forums to no avail, so I figured maybe you could help. (I am an absolute novice)

I have two wires which have DC current flowing through them. One has 5V DC at 500mA, and the other ranges from 10mV to 3.3V with a small varying current. The current has to flow in two directions for that second wire which is hooked up to something that is transmitting data over it, but I also need it to be turned on by that first wire. The data transmitted must be very finicky because I tried to test the current while there was data transfer using a multi-meter and the connected devices said there was not a connection.

I have been told that a TRIAC would work, as all I need is for the circuit to turn on once the first wire is active, and it will turn off once unplugged. I was hoping to allow free flowing current through the second wire, and have it activated by the 5V wire, but only minutely. And by this I mean that 5V still has to connect to a peripheral device which has to be driven by that 5V source.

I have looked at transistors and have no idea how to make sense of the datasheets. I attempted to use a relay, but to no avail. I think I may need a voltage regulator.

If you guys could direct me to a transistor/part/component which would work that would be great. Unfortunately I am kind of restricted to RadioShack or local electronics stores at the moment. I am in over my head with this project, and I did not expect it to involve additional electronics.

Thanks,
-Sterling

 

[doraemon]

Hello!

You need to tell us more.
Especially, "the current has to flow in 2 directions".
Usually, you have one power supply, (in this case with 5V output) and the current flows
from this power supply to some kind of load. Do you need a switch between the power
supply and the load, and this switch triggered from as mall signal?
Could you draw a schematic?

Dora.

 

[audiomik]

Sterling
although you say you have tried Relays, have a look at using a % Volt Reed relay such as:
https://uk.rs-online.com/web/p/reed-relays/1782703/

Connect the coil across your 5 Volt DC supply and have the switch contact in series with your Data link.

These components are easily available from many suppliers but the Datasheet from the RS webpage linked will help you with connecting it to your circuits.
If you have problems with residual noise, then connect a resistor between the signal input of your 'data receiver' and ground which is of a value such that the wanted signal still works.

hope this assists
Mik

 

[SBlevins]

The second wire where the current flows in two directions is controlled by a computer, so the current can flow in two directions I think. I have drawn up a crude example of my set up.



I may try the reed relay again. I tried using one, but the relay seems to have gone out, or something. When I test the contacts with a multimeter, it does not say there is a complete contact. This is for an Engineering project so, I am not sure I can qualify the relays as being possible to shrink down to size if the circuit was to be minimized in a "later" manufacturing process.

- - - Updated - - -

This is what I tried using to no avail: link