Remote Control Relays Basics – Power Supply

By default, and feasible in most circumstances, we use a fixed power supply either 12V or 24V to provide the power to our receiver, so we seldom consider the ratings etc. In this article we will give you a rough idea how much power will our receiver consume.

The following technical specifications are measured using 12VDC input power.

Current draw can be divided into 2 parts, the standby current and the working current when relay action.

Standby current includes mainly three parts, the receiver module, the MCU microprocessor and the voltage conversion circuit.

The powerful superheterodyne receiver circuit consumes most power around 8mA, the MCU’s current draw is very low less than 1mA, and since we’re using switching power supply’s high efficiency voltage conversion circuit, the power conversion consume is <1mA too.

To sum up, the total added standby current is around 8-10mA

Working current is when relay actions, and the current draw is largely depended on relay type and number, take our 202U receiver’s relay – SONGLE SRA-09VDC-CL for example, each relay will take 50mA when closed.

It seems like a much larger number compared to standby current ( 58mA vs 8mA ) especially when both relays are working ( 108mA vs 8mA ) but when time considered, the actual power draw is low, since the relay action time is very limited compared to power-up standby time.

The 8mA standby current has made battery operated nearly impossible, take a 9V alkaline battery for example, the total battery rating is 600mAh maximum, and using a battery calculator, we can see the standby time would be 52.5 hours, which means you have to change battery in less than 3 days.

As you can see, the main power consumer here is receiver circuit, so we may need to change the receiver circuit to low-power type if you want the receiver to be battery operated, but there is disadvantage of low-power receiver, which is shorter remote control distance compared to our standard component, so we have to choose and decide between longer battery life and longer remote control distance.