relay voltage rating

[rpapps]

Hi Jarthel
At the risk of throwing in another confusion factor, how about something like this.
It's an SY-4080 from Jaycar Electronics.

 

[rpapps]

Here's the datasheet.
Cost $12.
Cheers
Rob

 

[jarthel]

Hi Jarthel
At the risk of throwing in another confusion factor, how about something like this.
It's an SY-4080 from Jaycar Electronics.

do you think it would work with the ne555 circuit above?

 

[rpapps]

Hi
You would need a small modification to the circuit.
The 555 output goes low (to ground) to operate the mechanical relay whereas the SS relay requires a positive voltage of 3 or more so you need a transistor to invert that signal.
Cheers
Rob

 

[jarthel]

using a mechanical relay, one side of the coil is connected to the reset of the ne555 (pin8) and the other side is connected to trigger (pin7)

with your changes, what happens to these connections?

 

[rpapps]

Hi
The relay is actually connected to pin 3 (output) and pin 4 which is connected to the + supply. Neither of the two diodes shown would be needed. My mod would take its input from pin 3 and its + and ground connections from the equivalent pins on the 555.
Cheers
Rob

 

[jarthel]

ground connections from the equivalent pins on the 555.
Cheers
Rob

do you mean power supply ground? cause the only ground connection of the 555 is connected to power supply ground.

 

[rpapps]

Hi
Yes that's right.
I simplified the circuit a bit.
Cheers
Rob

 

[jarthel]

should it look like something like this? :

An externally hosted image should be here but it was not working when we last tested it.

 

[jarthel]

Hi
Yes that's right.
I simplified the circuit a bit.
Cheers
Rob

I assume the "reset" pin of the n3555 is not needed anymore?

 

[rpapps]

Yes it is. Just leave it connected to the + supply as shown in your original circuit.

 

[jarthel]

Yes it is. Just leave it connected to the + supply as shown in your original circuit.

thank you very much. looking for a relay that will work in either 9 or 10V is so hard in this country! :| even when looking at RS

 

[jarthel]

any suggestion for a bc108 substiute? that's available in jaycar?

 

[rpapps]

Hi
You're welcome.
Perhaps this will make it clearer for you.
PN100 will do as a substitute (Catalog # ZT-2283) and cheap @ $0.25.
Cheers
Rob

 

[jarthel]

thank you for the help

 

[rpapps]

Hi Jarthel
I thought about it some more and it can be done more simply.
Cheers
Rob

 

[jarthel]

Hi Jarthel
I thought about it some more and it can be done more simply.
Cheers
Rob

any reason for the change? also, why is the "-" pin of the relay on the trigger? (i think it's the trigger)

thanks again

 

[mrshow4u]

...instead of inverting the state of the output of the 555, couldn't you just "tug" on the low side of the SS relay's LED?? and have the Hi side pulled up to supply


....oops, I saw above post . Sorry for being late

 

[rpapps]

Hi Jarthel
Reason for change is just to make it simpler - fewer parts, easier to make. I should have thought of it earlier but I'm >57 and not as quick as I used to be.
The + of the relay goes to + supply via the current limiting resistor and the - of the relay is pulled to ground by the 555 output. It's just another way of defurring a feline.
Cheers
Rob

 

[jarthel]

the original circuits uses diodes (possibly for protection). do I need to put them back?