Author Topic: using a mechanical relay  (Read 446 times)

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Offline Adhith

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using a mechanical relay
« on: December 01, 2017, 04:49:25 am »
hello everyone..
I'm actually new to work with relay and AC power supply. I'm planning to drive a adenoidal valve which works on AC mains. I want it to be controlled using a 9V battery. So if I go for using mechanical relay how should be the connection?? also How should I connect the fly back diode??
 

Offline retrolefty

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Re: using a mechanical relay
« Reply #1 on: December 01, 2017, 05:17:48 am »
If your going to power the relay coil with 9 volt battery then the only real choice for a relay is a latching relay that draws coil power only during switching, not when steady on or off.

 

Offline Old Don

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Re: using a mechanical relay
« Reply #2 on: December 01, 2017, 12:45:30 pm »
You'll need a relay with contacts rated for 250 VAC or more plus a coil that works on 9 VDC. (or maybe 6 to 12 VDC). With a latching relay you can use a SPDT momentary switch to toggle the relay. No flyback diode needed in that case. Only needed if driving it from solid state device.
Retired - Formerly: Navy ET, University of Buffalo Electronic Tech, Field Engineer and former laptop repair business owner
 

Offline danadak

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Re: using a mechanical relay
« Reply #3 on: December 01, 2017, 10:45:19 pm »



If you are using a mechanical switch in lieu of transistor still use
diode clamp.


Regards, Dana.
« Last Edit: December 01, 2017, 10:52:46 pm by danadak »
Love Cypress PSOC, ATTiny, Bit Slice, OpAmps, Oscilloscopes, and Analog Gurus like Pease, Miller, Widlar, Dobkin, obsessed with being an engineer
 

Offline perieanuo

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Re: using a mechanical relay
« Reply #4 on: December 02, 2017, 06:59:44 am »
S202S12

Envoyé de mon HUAWEI NXT-L29 en utilisant Tapatalk

 

Offline Adhith

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Re: using a mechanical relay
« Reply #5 on: December 02, 2017, 07:23:24 am »
my question is if A, B are the terminals of the diode and if A is fed with +ve supply and B -ve then how should I connect the diode??
 

Offline Hero999

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Re: using a mechanical relay
« Reply #6 on: December 02, 2017, 08:37:17 am »
my question is if A, B are the terminals of the diode and if A is fed with +ve supply and B -ve then how should I connect the diode??
What do you mean? The terminals of the diode are anode and cathode, which is often abbreviated to A and K. The diode always goes in reverse parallel with the relay coil, with the anode going to negative and the cathode to positive. The reason for this is the diode only conducts, when the relay is turned off. When it's turned on, the diode needs to be reverse biased, so it doesn't pass any current.
 


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