A new idea.

[Steve108]

When considering how I could build a simple electric switch driven by my reciever I thought up this idea. Maybe some of you electronics experts could tell me if it would work. It is a lot simpler then everything else I've seen.

I'm thinking I'll need a transistor too, but don't understand how to hook one up. Maybe someone could draw that up. The zener diode will be tuned to where the relay trip point is. As the PWM increases, so will the voltage percieved by the diode and once it hits a certain point it will "break down" and activate the relay. I might need a capacitor too.

Thanks for any advice,

Steve

[westfw]

The zener diode will be tuned to where the relay trip point is. As the PWM increases, so will the voltage percieved by the diode and once it hits a certain point it will "break down" and activate the relay.

I don't think it will work. the PWM signal is only 2ms max out of a 50ms or
so frame (and 1ms min), so you're looking at an "average voltage" of
between 5*2/50 = 0.2V and 0.1V, and you can't get relays that operate
down there. Even if you somehow tuned a filter to eventually (several frames)
reach a higher voltage, there wouldn't be enough average power there to
hold a relay closed. You could throw some analog electronics at the issue,
but by that time you might as well throw a $0.50 microcontroller or 555 circuit
at the problem and solve it more "cleanly."

BillW

[Discharger]

Try this....

www.uoguelph.ca/~antoon/gadgets/rc-sw.htm

[Steve108]

Thanks, I forgot that the same current needed to trip the relay. Oh well, BTW I have a 555 chip laying around, do you have a circuit to use that?

Thanks again,

Steve

[Miami Mike]

Why not just use the pc board from a broken servo? Connect a 5 volt relay with a diode in series in place of the motor, and secure the potentiometer at the halfway point.

The relay I use in my Solenoid Safety Buzzer circuit (http://www.vvsss.com/buzzer/) should work well.