Hello,
I am hoping if someone can tell me what rating transistor should I use for the trigger in this delay relay
http://www.aaroncake.net/circuits/relaytim.asp

and also what transistor I can use to replace the 9V relay with?

Also I do not know how to tell the + and - ends of the NTE MLR103K50 AND NTE NEV10M50AA capacitors I bought.

Thanks.
Shaun.

 

The MLR103K50 is a mylar capacitor so is not polarised. It will work either way around.

The NEV10M50AA will have a stripe in one side of the body, in that stripe will be -ve symbols. The stripe will be adjacent to the negative terminal of the capacitor.

JimB

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Experience is directly proportional to the value of the equipment ruined.

 

Just about any NPN transistor will work. It will only have to have about a tenth of a milliamp flow through it so it can be pretty small. Something like a 2n3904 or 2n2222 should work fine. (depending on how you are triggering it)

On the MLR103K50 capacitor it is non-polarized, so you can hook it up any way you want. On the other one, the - lead will be on the side with the stripe.

Edit: it looks like someone answered the capacitor question before me.

 

Thanks guys.

Turns out my trigger source is a constant 12vdc, so I'm being told to put a resistor and coupling capacitor (1uf) at the collector (resistor before or after the capacitor?), and 10k ohm resistor at the base (where the 12v will be at constantly). When not at 12vdc the trigger is at 0v so I think I do not need the additional 10k ohm resistor from the base to ground.

So both the trigger transistor and a transistor to replace the 7v relay can be of the 2n3904, 2n2222, BC547 type?

Thanks.

 

I am not quite sure what you are trying to do with this circuit. I would imagine a 2n3904 or similar would work for the triggering but without knowing exactly how you would have it configured, I can't be 100% sure. If you are going to replace the relay with a transistor, you will need to find a transistor that is suited for your load. Without knowing what exactly you are switching on, I can't help you much more with that

 

the trigger itself will be on (12vdc) for possibly hours, I was told 12vdc to the base would fry it, so to put a 10k ohm resistor at the base in series from the trigger. And to maintain the timer function of the 555, the trigger pin #2 has to be pulsed I guess, so I was told to put a coupling capacitor w/ resistor before the collector.

The load is really not a load imo, its to close a circuit that isn't to a load but a 10 second pulse to a ECU to turn a function off, so I thought the relay was overkill.

Thanks

edit.

 

Shaun,
You are bouncing between two different forums. People here don't know what we talked about on the other forum so it is very confusing to them.
Please stay in only one forum.

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Uncle $crooge

 

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