555 or one shot

[LESpark]

Right, connected this up exactly as you suggested after finding which 2 of the 3 terminals are connected when off, com and CB (CK was the other)

Illuminated the led for around 2 seconds and went out, did this 3 times and now all it does is stay on perminantly, any reason for this other than a faulty unit?

 

[Bluejets]

Perhaps.......how is everything connected?
Can you sketch a circuit of what you have and how it is powered?

 

[LESpark]

Perhaps.......how is everything connected?
Can you sketch a circuit of what you have and how it is powered?

Photo in the post above

 

[Bluejets]

If there were enough detail in the above photo I would not have asked.

 

[LESpark]

Ahh ok, does this make sense?

 

[Bluejets]

Yes, seems ok.

Didn't do anything to damage the module at all.......reverse input .......higher than 12v input ??

How is it switched on and off ?

Does the relay click on and off ?

If not then just a dodgy unit by the looks of it.

 

[LESpark]

Excuse my ignorance, what do you mean

"reverse input .......higher than 12v input ??"

I was just testing the unit, the intended purpose is to use the ignition switch of the car to power (switch on) the unit

The one thing that I see as a problem is perhaps the voltage of the car with the alterbator is 13.4v, the device is 12v so I'm going to have to drop the voltage to the unit.

Could the 12.9/13v from the battery have killed the unit?

As said before, it didn't completely kill the unit it just didn't turn off abymoan

 

[Bluejets]

555 's are usually ok with more than 12v so I wouldn't be concerned with 13.4v.

reverse input = connecting the positive and negative the wrong way around on the input.

The unit you have is still the original delay turn on unit ?

If so and you are using it in the opposite logic via the relay then it appears the unit is dead.
A few tests in and around the circuit would confirm it but at a couple of dollars, not worth the effort seeing you wanted a quick and simple solution, buy another one.

 

[LESpark]

The bloke I bought it from said he would bung another in the post tomorrow and I've ordered 3 more just incase, so I should be ok without putting a resistor between the battery and the input on the device

 

[AnalogKid]

OR, let's assume 4 mA at 12 V for the LED. A 2.2K or 2.7K resistor and a 1500 uF capacitor will hold the LED on for the required time. The LED will fade away rather than snap off. No chips, no transistors, no PICs, no Arduinos. One R, one C, that's it.

ak

 

[(*steve*)]

I hope you didn't power this from your car battery with the engine running did you?

Or maybe, even just once, maybe just for an instant, connect it up to the battery the wrong way around?