230V Relay Switching Problem with RF

230v relay switching problem with rf
Hi,

I'm facing relay switching problem by using RF.I'm using the relay in RF Receiver side.I tried with RC snubber circuit in relay coil and relay contacts.But i can't find any solution for that.Relay switching time differs for snubber circuit(tried with different R and C combinations).

I couldn't switch the relay for right timing through RF receiver. Pls give solutions for this......

Here i'm using industrial gong bell as a load.

RF input is given to transistor base.

You have to make sure that the circuit driving the relay is clean and powerful enough to activate the relay.

Measure the resistance of the relay and put the same value resistor in the circuit and look at the signal across the resistor with a CRO.

Put the CRO screen images on the web.

hi

thanks for your reply.

Without load relay on/off is fine.When we connect the load relay turned on at the right time if RF signal received.But couldn't turn off right time.

ok fine where i can put the resistor. across relay or where

Make the relay activate another relay and the second relay switches your load.

use a transient voltage suppressor diode TVS 5v before the base resistor,

use 0.1 cap on both end of base resistor.

provide in4007 diode across the rly coil in reverse biased for protection from back emf (applies for dc rly )


provide 47 mfd 100v cap across the rly coil to avoid rly chattering which can generate (applies for dc rly )
noise/spikes ,the cap improves rly holding current.

provide 0.22 -400v cap from collector of transistor to ground.

better to use only one rly for switching for good results.

I changed the snubber circuit(R&C combination,resistance value changed to same value of relay coil resistance).
It's working fine up to 30 mins...After that it's create malfunction....What is the reason for malfunction...

Hi,vijay kumar
1. Make sure your power supply is free fr hum& noise.provide 0.01 cap across all rectifier diodes.
2. Never connect the ground terminal of the plug point directly to your transformer ground provide a 22 ohms 3 watt resistor series from the ac socket ground to your chassis ground because when you connect the negative of your power supply to the chassis all the noise will enter your power supply causing interment switching problems.
when the resistor comes in series with the earth terminal it creates a separate earth loop
causing a minute earth loop voltage drop across the resistor and avoid the noises reaching your power supply,also provide 0.22 450v cap on the pri of your transformer and also on the out put of the rly contact (phase ) to the netural .