2 Relays with alternate on/off using Voltage divider

Thread Starter

imani9009

Joined Nov 8, 2013
56
HI,
I want to make a circuit that turns on a relay with led when i latch the button and turn off the other relay with resistance. If button is in off position the relay with resistor should be on and other led relay should be off. the relay can operated at not less than 9 volt with 430 ohm resistance and 21mA current rating. the power supply could be 24 volt or 9 volt.
battery 2.1.3 (potential divider).png
 

LowQCab

Joined Nov 6, 2012
2,512
The Schematic You have provided will not work.
What is the overall picture ?, what are You trying to accomplish ?
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.
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Thread Starter

imani9009

Joined Nov 8, 2013
56
The Schematic You have provided will not work.
What is the overall picture ?, what are You trying to accomplish ?
.
.
.
I Want to turn relay with led to switch on when i latch the button, the other relay should be off this time,
when i turn the button off the relay with resistance should be on and other relay should be off.
 

Thread Starter

imani9009

Joined Nov 8, 2013
56
I Want this circuit to be used for 24 volt battery voltage monitor circuit, the position where is switch there is npn transistorScreenshot_20220818-174103_Chrome.jpg
 

vu2nan

Joined Sep 11, 2014
274
Hi imani9009,

Here's the schematic.

A single 24 V DC relay should suffice.

123.png

With the relay energised, the green LED will be on and the red off and vice versa.

Nandu.
 
Last edited:

BobTPH

Joined Jun 5, 2013
5,809
If you want to detect a voltage threshold, there is a component designed to this this. It is called a comparator. Using the trigger voltage of a relay will never be very accurate.
 

KeithWalker

Joined Jul 10, 2017
2,524
A circuit designed to operate using the drop-out current of a relay will not be reliable. The relay coil resistance will change with temperature and relays of the same type will have different drop-out characteristics.
 

Reloadron

Joined Jan 15, 2015
6,989
I want the relay to switch off with just minor voltage drop from 24 for example 23.5. Will this relay turn off at 23.5 or any other way to do this
If you look at the data sheets for relays you will note that a relay has a must operate and a must release voltage. Those numbers are not exactly perfect numbers. The relay manufacturer is telling you the relay should pull in at a given max voltage and not drop out before a given min voltage. You can't depend on this and before a relay pulls in or drops out they tend to chatter. Must operate is generally about 80% of the coil rated voltage Must release is about 30% of min rated voltage. It's all in the data sheets for quality relays.

As mentioned if you want to set a voltage threshold for something to happen you use a comparator circuit or a uC (micro-controller) circuit. If you don't want to roll your own a simple comparator module can be had inexpensive on Amazon or other sources. A Google of "comparator module amazon" will give you a dozen examples.

Ron
 

vu2nan

Joined Sep 11, 2014
274
I want the relay to switch off with just minor voltage drop from 24 for example 23.5. Will this relay turn off at 23.5 or any other way to do this
Hi imani9009,

The relay may be used only to display the on / off status of the supply.

For your redefined purpose a comparator would be ideal.

Nandu.
 
Last edited:

Ramussons

Joined May 3, 2013
1,316
HI,
I want to make a circuit that turns on a relay with led when i latch the button and turn off the other relay with resistance. If button is in off position the relay with resistor should be on and other led relay should be off. the relay can operated at not less than 9 volt with 430 ohm resistance and 21mA current rating. the power supply could be 24 volt or 9 volt.
View attachment 274766
If you have the Relay 2 with one more changeover contact, it can be done.
Use a DPDT relay 2.
 
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