collage project

[bloberts]

hi this may be the wrong place to ask but hay

anyho iv been set a project to build a ne555 timer to drive a 800ohm relay from a 9V dc supply it needs to have a 1:1 mark to space ratio.I have it compleated but the relay i need to drive is causing some problems it gets oscillation when it is at the top.

the relay is the green line

555 timer scpoe

[FenceMagnet]

"collage" huh? Is English your first language?

:confused:

[Acetronics]

Heuuuu,

Without mocking ...

En Français, on comprendra mieux ...

Did you place filtering capacitors on the supply line ?, and a catch diode on the relay coil ?

a little scheme would be rather welcome ...

Merci

Alain

[BushmanLA]

I'm not sure if I understand correctly but it seems like your circuit may be resetting when the relay is triggered because your power supply can't handle the sudden increase in current demand.

If this is the case, filter/decoupling capacitors should help things out and if they don't solve it, you will have to find a more robust power supply.

Try reposting the circuit image, it should make things clearer for us.

[Bruce Abbott]

The Electronics Club: 555 and 556 Timer Circuits (http://www.kpsec.freeuk.com/555timer.htm)

"the 555 and 556 require an extra diode connected in series with the coil to ensure that a small 'glitch' cannot be fed back into the IC. Without this extra diode monostable circuits may re-trigger themselves as the coil is switched off!"

[bloberts]

i will post the digram here when im next at collage as i dont have the simulators at home/work

[Tomapowa]

Couldn't resist...

http://en.wikipedia.org/wiki/Collage

... certainly follow Bruce's suggestion... I've been bitten by this many times in the past.

[Ron van Sommeren]

"collage" huh? Is English your first language?

:confused:Certainly not the way I would respond :( But English is not my first language too. This goes for lots of people around the world. Or did you forget a smiley?

Prettig weekend ;) Ron

[Acetronics]

Couldn't resist...

http://en.wikipedia.org/wiki/Collage





By the way, we could we could greet all the "cut and paste " pro's ... :D :D :D



Alain

[KaneTheMediocr]

I used a 555 astable circuit to simulate a receiver in my test bench. If I'm not mistaken, you can't quite get 1:1, but you can get very close by shorting a couple pins instead of putting a resistor there. So if you're looking for EXACTLY 1:1, you may be out of luck.

[Acetronics]

Hi, Kane

Did you ever use DIODES in the 555 R/C Ladder ...

looks you should consider that more than classical scheme ...

Alain

[mjsas]

âäà╒╘╙
Just about everyone (except relay manufactures) recommends putting a flywheel diode across the relay coil. The diode slows the opening of the relay contacts and will kill the relay faster then anything.
The correct surge suppressor circuit is to use a zener diode with a standard diode to increase the surge voltage to above 12 volts, I use 30 volt zeners.
The relay application note from Potter & Brumfield says that when the contacts weld it happens when the relay contacts are opening, not closing. The slowly opening contacts will bounce and weld. A flywheel diode will almost guarantee that the contacts weld for some loads.

[bloberts]

here is the ciruit digram with the scope attached the green one is the relay

[Acetronics]

Hi,

You didn't use any capacitor in the supply lines ... :censored:

Not good at all !!!

And Multisim is a Pricey tool ( 15000 US$ ... LOL ! ) , BUT... this is only SIMULATION :D ... not real world !!!

BY the way ... It would be really useful to look at your REAL WORLD scheme ... :rolleyes:

Alain

[bloberts]

well it has only been made as a sim

nice that they have paid for multisim

i will try the capacitors in the supply line to see if it makes any difference

[Acetronics]

Hi,

The Multisim 555 simulation is rather funny ... :D :D :D

Put your components on a breadboard and forget the virtual World !!!

... ha,ha,ha

15 000 US$ for THAT :censored:

Alain

PS: yes , I have a PowerPro Edition here :eek: ... but still use my Ultimate 5.72 suite :p (an elder edition ... without simulation... Thanks to God !!! ;) )