please i need ur help...!!!

[timothy]

i'm designing a project. i want to use a 555 timer ic to activate a relay and the relay remains stable. i know some other circuits will be involved apart from the 555 timer. please how do i make the relay stable after activating it with the 555 timer?. thanks.

 

[Nigel Goodwin]

i'm designing a project. i want to use a 555 timer ic to activate a relay and the relay remains stable. i know some other circuits will be involved apart from the 555 timer. please how do i make the relay stable after activating it with the 555 timer?. thanks.

I've no idea what you mean by 'stable'?, but assuming you want the relay to stay ON once it times out, you simply use the 555 in monostable mode.

 

[Phasor]

I've no idea what you mean by 'stable'?, but assuming you want the relay to stay ON once it times out, you simply use the 555 in monostable mode.

Wouldn't the relay turn OFF after timing out, in monostable mode? I think timothy is after a latching relay.

 

[Nigel Goodwin]

I've no idea what you mean by 'stable'?, but assuming you want the relay to stay ON once it times out, you simply use the 555 in monostable mode.

Wouldn't the relay turn OFF after timing out, in monostable mode? I think timothy is after a latching relay.

It works either way, depending what relay contacts you use! - with SPDT contacts on the relay you simply choose the way you want.

 

[Phasor]

It works either way, depending what relay contacts you use! - with SPDT contacts on the relay you simply choose the way you want.

I was assuming N/O contacts.

 

[Nigel Goodwin]

It works either way, depending what relay contacts you use! - with SPDT contacts on the relay you simply choose the way you want.

I was assuming N/O contacts.

In that case connect the relay coil between output and ground, rather than output and +ve (or should that be the other way round?). In any case, you can connect the relay coil to work either way.

 

[timothy]

this is the project: i want to use a remote to activate a fan. if i use the 555 in a monostable way, it will activate the relay and remain stable untill the 555 times out as a result of the delay. now i want something that will be stable permenently utill i press another button to deactivate it. the circuits consists of an infrared transmitter and reciever. the reciever passes an impulse to the trigger (pin 2) of the 555 and then the output (pin 3) activates the relay. but how to make the relay remain permenently in that activated state is where the problem lies. contribution please..............!!!

 

[eblc1388]

You want to use a 555 timer to acts as a bi-stable?

555 can easily be wired to be either a monostable or astable but seldom to be used as a bi-stable. Using it is a bad choice in the first place.

 

[williB]

Yes Tim a 555 is not the correct choice for your IR switch ..
all you need is an IR relay circuit ..

 

[timothy]

how can i get the remote relay circuit please?. i have built the IR transmitter and the reciever using CD4069 hex inverter. ur support please.

 

[audioguru]

Hi Timothy,
Connect the output stages of your CD4069 IR receiver like this:

 

[audioguru]

The pushbutton would be a transistor with a series base resistor.

 

[eblc1388]

The pushbutton would be a transistor with a series base resistor.

Unfortunately the transistor CE voltage polarity changes with the states of 4069.

 

[audioguru]

Hi L. Chung,
Transistors work when backwards, most Noobies find out. :shock: :shock:
Their gain is poor when backwards but they switch OK if you use a high base current. Since their base-emitter junction will avalanche when reverse-biased at about 6V to 7V, it is in series with a forward-biased collector-base junction so the supply voltage of the circuit should be less than 6.6V to 7.6V. :lol: :lol: