Splitting AC into two DC

Hi
I need to connect a digital control that requires 24V and closes a relay when a certain humidity is reached (a dehumidistat). The problem is that I have only two wires between my HVAC (load) and the humidistat (control).

I was thinking about the following idea: Create 2 DC sources (+33.6V and -33.6V) from one 24VAC source, by using two half-wave rectifiers. One rectifier would drive the control and the other one would drive the output, but only when the control relay is closed, using a diode to control the direction. Like this:


Let's assume that the control and load supports 33Vdc, would this circuit work? Am I missing something?

Is there another easy way to achieve what I need? Can I avoid using DC and keeping full-wave AC on the control without driving current through the load?
Keep in mind that I need maximum 2 conductors going to the control. The source and the load are away from the control.

I would use this::

https://www.amazon.com/dp/B000LESCI2/ref=cm_sw_r_sms_awd_x_RjKgyb9GPVDXM

Relay operates with AC or DC voltage

Works within the realm of what your needing.

If you already have the power source you don't need rectifiers etc

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Gary Sather

tonanzith wrote:

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If you already have the power source you don't need rectifiers etc

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My power source and the load (a relay) are in the closet. There is only a pair of wires going to the control in the wall (humidistat). So basically, I'm trying to carry 2 signals over the same pair of wires:
-A constant 24V input
-A switched 24V output

Usually, 3 wires are used to achieve this. But I have only two and I can't run a new wire inside the wall. I'm basically missing a common (or neutral) wire.

My idea in the circuit above is to use the positive half-wave for the input and the negative half-wave for the switched output. It's a sort of simplified power-stealing circuit that doesn't involve complex electronic and logic.

Update: My circuit works even without the capacitor across the control, a Honeywell H6062 working on 24VAC. It can handle half-wave 24VAC. I can activate the relay remotely using only 1 output wire. I only have to be careful not to plug anything in reverse.