Hello, this is my first posting to this forum, looks like there is a lot of knowledge here, maybe you can help me with a basic circuit problem.
I am designing a model railroad train detection circuit that will turn on a 5v relay when 18vac is sensed on a pair of wires coming from the track. The 18vac will signal that a train is on track. What i need is something simple that will watch for the 18vac and switch the relay (5v?) on without drawing too much power, and as a plus, work at lower ac voltages as well.
Here are some relay specs i am considering:
5v Dip Relay 57ohm coil, or 12v Dip Relay 740ohm coil.
Currently, forgive the pun, i have a circuit that rectifies the 18vac, regulates to 5v and powers a small relay. But the regulator generates too much heat at 18vdc, and i was hoping for a simpler, more efficient solution.
I suspect that you might recommend a transistor type circuit that gives an "on" output when the circuit input ranges between 5 and 18 volts AC. Problem is, i am not savvy enough about such circuits to design one on my own.
Thanks in advance.
-Miles
I am designing a model railroad train detection circuit that will turn on a 5v relay when 18vac is sensed on a pair of wires coming from the track. The 18vac will signal that a train is on track. What i need is something simple that will watch for the 18vac and switch the relay (5v?) on without drawing too much power, and as a plus, work at lower ac voltages as well.
Here are some relay specs i am considering:
5v Dip Relay 57ohm coil, or 12v Dip Relay 740ohm coil.
Currently, forgive the pun, i have a circuit that rectifies the 18vac, regulates to 5v and powers a small relay. But the regulator generates too much heat at 18vdc, and i was hoping for a simpler, more efficient solution.
I suspect that you might recommend a transistor type circuit that gives an "on" output when the circuit input ranges between 5 and 18 volts AC. Problem is, i am not savvy enough about such circuits to design one on my own.
Thanks in advance.
-Miles